DODGE RAM 1999 Service Repair Manual

CONDITION under SELF-DIAGNOSTIC SYSTEM. Testing is complete.
5) Turn ignition off. Disconnect transmission solenoid
harness connector. Inspect connector and terminals for damage. Repair
as necessary. If connector and terminals are okay, turn ignition on.
Using scan tool, actuate transmission control relay. Measure voltage
between ground and transmission relay output circuit at transmission
solenoid harness connector. If voltage does not switch from zero to
greater than 10 volts, go to step 18). If voltage switches from zero
to greater than 10 volts, go to next step.
6) Turn ignition off. Disconnect PCM harness connectors.
Inspect connectors and terminals for damage. Repair as necessary. If
connectors and terminals are okay, turn ignition on. Measure voltage
between ground and governor pressure solenoid control circuit at
transmission solenoid harness connector. If voltage is greater than 10
volts, go to step 8). If voltage is 10 volts or less, go to next step.
7) Repair governor pressure solenoid control circuit for
short to ground. Reconnect all disconnected harness connectors. Using
scan tool, perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 1st
gear and read governor pressure voltage. If voltage is one volt or
greater, replace PCM. If voltage is less than one volt, test is
complete.
8) Turn ignition off. Reconnect transmission solenoid harness
connector. Measure resistance between ground and governor pressure
solenoid control circuit at White PCM harness connector C2. If
resistance is 5 ohms or less, repair short to ground in governor
pressure solenoid control circuit. If resistance is greater than 5
ohms, go to next step.
9) Remove transmission control relay. Inspect transmission
control relay connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, measure resistance between
transmission control relay output circuit at transmission control
relay connector and governor pressure solenoid control circuit at
White PCM harness connector C2. If resistance is 2.5-5.0 ohms, replace
PCM. If resistance is not 2.5-5.0 ohms, go to next step.
10) Measure resistance between transmission control relay
output circuit at transmission control relay connector and governor
pressure solenoid control circuit at White PCM harness connector C2.
If resistance is greater than 5 ohms, go to next step. If resistance
is 5 ohms or less, go to step 13).
11) Disconnect transmission solenoid harness connector.
Inspect connector and terminals for damage. Repair as necessary. If
connector and terminals are okay, measure resistance of governor
pressure solenoid control circuit between White PCM harness connector
C2 and transmission solenoid harness connector. If resistance is
greater than 5 ohms, repair open governor pressure solenoid control.
If resistance is 5 ohms or less, go to next step.
12) Drain transmission fluid and remove oil pan. Disconnect
governor pressure solenoid harness connector. Inspect connector and
terminals for damage. Repair as necessary. If connector and terminals
are okay, measure resistance across governor pressure solenoid
terminals. If resistance is 5 ohms or less, repair or replace
transmission solenoid and harness assembly. If resistance is greater
than 5 ohms, replace governor pressure solenoid.
13) Disconnect transmission solenoid harness connector.
Inspect connector and terminals for damage. Repair as necessary. If
connector and terminals are okay, measure resistance between governor
pressure solenoid control circuit and all other circuits at
transmission solenoid harness connector. If resistance is less than 2.
5 ohms between any 2 circuits, go to next step. If resistance is not
less than 2.5 ohms between any 2 circuits, go to step 15).
14) Repair governor pressure solenoid control circuits that
were shorted together. Reconnect all disconnected harness connectors.
Using scan tool, perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select

1st gear and read governor pressure voltage. If voltage is one volt or
greater, replace PCM. If voltage is less than one volt, test is
complete.
15) Drain transmission fluid and remove oil pan. Disconnect
governor pressure solenoid harness connector. Inspect connector and
terminals for damage. Repair as necessary. If connector and terminals
are okay, measure resistance across governor pressure solenoid
terminals. If resistance is 2.5 ohms or less, go to next step. If
resistance is greater than 2.5 ohms, go to step 17).
16) Replace governor pressure solenoid. Replace oil pan and
fill with fluid. Reconnect all disconnected harness connectors. Using
scan tool, perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 1st
gear and read governor pressure voltage. If voltage is one volt or
greater, replace PCM. If voltage is less than one volt, test is
complete.
17) Repair or replace transmission solenoid and harness
assembly. Reconnect all disconnected harness connectors. Using scan
tool, perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 1st gear and
read governor pressure voltage. If voltage is one volt or greater,
replace PCM. If voltage is less than one volt, test is complete.
18) Remove transmission control relay. Inspect transmission
control relay connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, turn ignition on. Measure voltage
between ground and fused B+ circuit at transmission control relay
connector. If voltage is 10 volts or less, repair open fused B+
circuit. If voltage is greater than 10 volts, go to next step.
19) Turn ignition off. Measure resistance of transmission
control relay output circuit at transmission control relay connector
and TCC solenoid harness connector. If resistance is greater than 5
ohms, repair open transmission control relay output circuit. If
resistance is 5 ohms or less, go to next step.
20) Measure resistance between ground and transmission
control relay output circuit at transmission solenoid harness
connector. If resistance is less than 5 ohms, repair open in
transmission control relay output circuit. If resistance is 5 ohms or
greater, replace transmission control relay.
Diagnostic Procedure (AB, BR & WJ Bodies)
NOTE: On WJ body, if all solenoid codes, P0743, P0748 and P0753 are
set, go to test DTC P1765: TRANS 12-VOLT SUPPLY RELAY CNTRL
CIRCUIT before proceeding.
1) Using scan tool, read DTCs. On BR and WJ bodies, go to
next step. On AB body, if DTC SPECIFIC GOOD TRIPS counter is not
displayed or displayed count is not "0", go to step 20). If DTC
SPECIFIC GOOD TRIPS counter is displayed and displayed count is "0",
indicating DTC still exists, go to next step.
2) If DTC P1765 is also set, go to DTC DTC P1765: TRANS 12-
VOLT SUPPLY RELAY CNTRL CIRCUIT. If DTC P1765 is not set, go to next
step.
3) Using scan tool, perform GOV and 3-4 SHIFT VALVE SYSTEM
TEST. Select 1st gear and read governor pressure voltage. If voltage
is one volt or greater, go to step 20). If voltage is less than one
volt, go to next step.
4) Turn ignition off. Disconnect transmission solenoid
harness connector. Turn ignition on. Using scan tool, actuate
transmission control relay. Measure voltage between ground and
transmission relay output circuit at transmission solenoid harness
connector. If voltage does not switch from zero to greater than 10
volts, go to step 17). If voltage switches from zero to greater than
10 volts, go to next step.
5) Turn ignition off. Disconnect PCM harness connectors.

Inspect connectors and terminals for damage. Repair as necessary. If
connectors and terminals are okay, turn ignition on. Measure voltage
between ground and governor pressure solenoid control circuit at
transmission solenoid harness connector. If voltage is greater than 10
volts, go to next step. If voltage is 10 volts or less, go to step 7).
6) Repair governor pressure solenoid control circuit for
short to voltage. Reconnect all disconnected harness connectors. Using
scan tool, perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 1st
gear and read governor pressure voltage. If voltage is one volt or
greater, replace PCM. If voltage is less than one volt, test is
complete.
7) Turn ignition off. Reconnect transmission solenoid harness
connector. Measure resistance between ground and governor pressure
solenoid control circuit at White PCM harness connector C2. If
resistance is 5 ohms or less, repair short to ground in governor
pressure solenoid control circuit. If resistance is greater than 5
ohms, go to next step.
8) Remove transmission control relay. Inspect transmission
control relay connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, measure resistance between
transmission control relay output circuit at transmission control
relay connector and governor pressure solenoid control circuit at
White PCM harness connector C2. If resistance is 2.5-5.0 ohms, replace
PCM. If resistance is not 2.5-5.0 ohms, go to next step.
9) Measure resistance between transmission control relay
output circuit at transmission control relay connector and governor
pressure solenoid control circuit at White PCM harness connector C2.
If resistance is greater than 5 ohms, go to next step. If resistance
is 5 ohms or less, go to step 12).
10) Drain transmission fluid and remove oil pan. Disconnect
governor pressure solenoid harness connector. Inspect connector and
terminals for damage. Repair as necessary. If connector and terminals
are okay, measure resistance across governor pressure solenoid
terminals. If resistance is 5 ohms or less, repair or replace
transmission solenoid and harness assembly. If resistance is greater
than 5 ohms, go to next step.
11) Measure resistance of governor pressure solenoid control
circuit between White PCM harness connector C2 and transmission
solenoid harness connector. If resistance is greater than 5 ohms,
repair open governor pressure solenoid control circuit. If resistance
is 5 ohms or less, replace governor pressure solenoid.
12) Measure resistance between governor pressure solenoid
control circuit and all other circuits at transmission solenoid
harness connector. If resistance is less than 2.5 ohms between any 2
circuits, go to next step. If resistance is not less than 2.5 ohms
between any 2 circuits, go to step 14).
13) Repair governor pressure solenoid control circuits that
were shorted together. Reconnect all disconnected harness connectors.
Using scan tool, perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select
1st gear and read governor pressure voltage. If voltage is one volt or
greater, replace PCM. If voltage is less than one volt, test is
complete.
14) Drain transmission fluid and remove oil pan. Disconnect
governor pressure solenoid harness connector. Inspect connector and
terminals for damage. Repair as necessary. If connector and terminals
are okay, measure resistance across governor pressure solenoid
terminals. If resistance is 2.5 ohms or less, go to next step. If
resistance is greater than 2.5 ohms, go to step 16).
15) Replace governor pressure solenoid. Replace oil pan and
fill with fluid. Reconnect all disconnected harness connectors. Using
scan tool, perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 1st
gear and read governor pressure voltage. If voltage is one volt or
greater, replace PCM. If voltage is less than one volt, test is

complete.
16) Repair or replace transmission solenoid and harness
assembly. Reconnect all disconnected harness connectors. Using scan
tool, perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 1st gear and
read governor pressure voltage. If voltage is one volt or greater,
replace PCM. If voltage is less than one volt, test is complete.
17) Remove transmission control relay. Inspect transmission
control relay connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, turn ignition on. Measure voltage
between ground and fused B+ circuit at transmission control relay
connector. If voltage is 10 volts or less, repair open fused B+
circuit. If voltage is greater than 10 volts, go to next step.
18) Turn ignition off. Measure resistance of transmission
control relay output circuit at transmission control relay connector
and TCC solenoid harness connector. If resistance is greater than 5
ohms, repair open transmission control relay output circuit. If
resistance is 5 ohms or less, go to next step.
19) Measure resistance between ground and transmission
control relay output circuit at transmission solenoid harness
connector. If resistance is less than 5 ohms, repair short to ground
in transmission control relay output circuit. If resistance is 5 ohms
or greater, replace transmission control relay.
20) Using scan tool, erase DTCs. Start engine. Using scan
tool, read DTCs while wiggling wiring harness between governor
pressure solenoid and PCM. Note if DTC P0748 resets. If DTC P0748
resets, repair wiring harness as necessary. If DTC P0748 does not
reset, go to next step.
21) Inspect all related wiring and connectors. Repair as
necessary. If wiring and connectors are okay, see INACTIVE DTC
CONDITION under SELF-DIAGNOSTIC SYSTEM. Testing is complete.
DTC P0751: O/D SWITCH PRESSED (LO) MORE THAN 5 MIN
Circuit Description
Circuit is monitored after engine is running for 10 seconds
and reviewed every 440ms. Code sets if overdrive switch is held low
for 5 minutes or more from time of closure or ignition on.
Possible Causes
* Fused B+ circuit open.
* Solenoid and harness assembly defective.
* Governor pressure solenoid out of tolerance.
* Transmission control relay defective.
* Governor pressure solenoid control circuit shorted to
ground.
* Governor pressure solenoid harness defective.
* Governor pressure solenoid control circuit open.
* Transmission control relay output circuit open.
* Transmission control relay output circuit shorted to
ground.
* PCM defective.
Diagnostic Procedure
1) Turn ignition off. Disconnect PCM harness connectors.
Inspect connectors and terminals for damage. Repair as necessary. If
connectors and terminals are okay, measure resistance between ground
and Overdrive (O/D) off switch sense circuit at Gray PCM harness
connector C3. If resistance is less than 5 ohms, go to next step. If
resistance is 5 ohms or greater, go to step 3).
2) Disconnect O/D switch harness connector. Inspect connector
and terminals for damage. Repair as necessary. If connector and
terminals are okay, measure resistance between ground and O/D off

switch sense circuit at O/D switch harness connector. If resistance is
less than 5 ohms, repair short to ground in O/D switch sense circuit.
If resistance is 5 ohms or greater, replace O/D off switch.
3) Conditions required to set DTC P0751 are not present at
this time. DTC P0751 sets if PCM senses O/D off switch input is held
low for 5 minutes or from time of closure or ignition on. Possible
causes are: faulty O/D OFF switch, shorted wire or faulty PCM. Inspect
all related wiring and connectors. Repair as necessary. If wiring and
connectors are okay, see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC
SYSTEM. Testing is complete.
DTC P0753: TRANS 3-4 SHIFT SOLENOID/TRANS RELAY CIRCUITS
Circuit Description
Circuit is monitored continuously while key is on. Code sets
if voltage detected on 3-4 shift solenoid control circuit at the
Powertrain Control Module (PCM) does not match expected voltage.
Possible Causes
* Transmission mechanically defective.
* TPS codes set.
* Transmission 3-4 solenoid wiring harness defective.
* Transmission fluid burnt or oil pan has excessive debris.
* Shift control solenoid circuit shorted to ground.
* Solenoid and harness assembly defective.
* Transmission control relay output circuit open.
* Transmission control relay output circuit shorted to
ground.
* PCM defective.
Diagnostic Procedure (AN & DN Bodies)
1) If DTC P1765 is also set, go to DTC P1765: TRANS 12-VOLT
SUPPLY RELAY CNTRL CIRCUIT. If DTC P1765 is not set, go to next step.
2) Road test vehicle and reach a speed of 50 MPH. Depress
Overdrive (OD) switch 4 times so vehicle attempts to shift from 4th
gear to 3rd gear and back. If vehicle does not shift between 3rd and
4th gear, go to step 5). If vehicle shifts between 3rd and 4th gear,
go to next step.
3) Using scan tool, erase DTCs. Start engine. Using scan
tool, read DTCs while wiggling wiring harness between 3-4 shift
solenoid and PCM. If DTC P0753 resets, repair wiring harness as
necessary. If DTC P0753 does not reset, go to next step.
4) Using wiring diagram as a guide, inspect wiring and
connectors. Repair wiring harness as necessary. If wiring and
connectors are okay, see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC
SYSTEM. Testing is complete.
5) Turn ignition off. Disconnect transmission solenoid
harness connector. Turn ignition on. Using scan tool, actuate
transmission control relay. Measure voltage between ground and
transmission relay output circuit at transmission solenoid harness
connector. If voltage does not switch from zero to greater than 10
volts, go to step 16). If voltage switches from zero to greater than
10 volts, go to next step.
6) Turn ignition off. Disconnect PCM harness connectors.
Inspect connectors and terminals for damage. Repair as necessary. If
connectors and terminals are okay, turn ignition on. Measure voltage
between ground and 3-4 shift solenoid control circuit at transmission
solenoid harness connector. If voltage is greater than 10 volts, go to
next step. If voltage is 10 volts or less, go to step 8).
7) Repair 3-4 shift solenoid control circuit for short to
voltage. Reconnect all disconnected harness connectors. Road test
vehicle and reach a speed of 50 MPH. Depress Overdrive (OD) switch 4

times so that vehicle attempts to shift from 4thgear to 3rd gear and
back. If vehicle does not shift between 3rd and 4th gear, replace PCM.
If vehicle shifts between 3rd and 4th gear, testing is complete.
8) Turn ignition off. Measure resistance between ground and
3-4 shift solenoid control circuit at White PCM harness connector C2.
If resistance is less than 5 ohms, repair short to ground in 3-4 shift
solenoid control circuit. If resistance is 5 ohms or greater, go to
next step.
9) Reconnect transmission solenoid harness connector. Measure
resistance between ground and 3-4 shift solenoid control circuit at
White PCM harness connector C2. If resistance is less than 5 ohms,
replace transmission solenoid harness assembly. If resistance is 5
ohms or greater, go to next step.
10) Remove transmission control relay. Inspect transmission
control relay connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, measure resistance between
transmission control relay output circuit at transmission control
relay connector and 3-4 shift solenoid control circuit at White PCM
harness connector C2. If resistance is 26-40 ohms, replace PCM. If
resistance is not 26-40 ohms, go to next step.
11) Measure resistance between transmission control relay
output circuit at transmission control relay connector and 3-4 shift
solenoid control circuit at White PCM harness connector C2. If
resistance is greater than 40 ohms, go to next step. If resistance is
less than 26 ohms, go to step 13).
12) Disconnect transmission solenoid harness connector.
Inspect connector and terminals for damage. Repair as necessary. If
connector and terminals are okay, measure resistance of 3-4 shift
solenoid circuit between White PCM harness connector C2 and
transmission solenoid harness connector. If resistance is 5 ohms or
greater, repair open 3-4 shift solenoid circuit. If resistance is less
than 5 ohms, replace transmission solenoid and harness assembly.
13) Disconnect transmission solenoid harness connector.
Inspect connector and terminals for damage. Repair as necessary. If
connector and terminals are okay, measure resistance of 3-4 shift
solenoid circuit and all other circuits at transmission solenoid
harness connector. If resistance is less than 5 ohms between any 2
circuits, go to next step. If resistance is not less than 5 ohms
between any 2 circuits, go to step 15).
14) Repair 3-4 shift solenoid control circuits that were
shorted together. Reconnect all disconnected harness connectors. Road
test vehicle and reach a speed of 50 MPH. Depress Overdrive (OD)
switch 4 times so that vehicle attempts to shift from 4thgear to 3rd
gear and back. If vehicle does not shift between 3rd and 4th gear,
replace PCM. If vehicle shifts between 3rd and 4th gear, testing is
complete.
15) Replace transmission harness inside transmission and
solenoid pack assembly. Reconnect all disconnected harness connectors.
Road test vehicle and reach a speed of 50 MPH. Depress Overdrive (OD)
switch 4 times so that vehicle attempts to shift from 4th gear to 3rd
gear and back. If vehicle does not shift between 3rd and 4th gear,
replace PCM. If vehicle shifts between 3rd and 4th gear, testing is
complete.
16) Remove transmission control relay. Inspect transmission
control relay connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, turn ignition on. Measure voltage
between ground and fused B+ circuit at transmission control relay
connector. If voltage is 10 volts or less, repair open fused B+
circuit. If voltage is greater than 10 volts, go to next step.
17) Turn ignition off. Measure resistance of transmission
control relay output circuit at transmission control relay connector
and TCC solenoid harness connector. If resistance is greater than 5
ohms, repair open transmission control relay output circuit. If

resistance is 5 ohms or less, go to next step.
18) Measure resistance between ground and transmission
control relay output circuit at transmission solenoid harness
connector. If resistance is less than 5 ohms, repair short to ground
in transmission control relay output circuit. If resistance is 5 ohms
or greater, replace transmission control relay.
Diagnostic Procedure (AB & BR Bodies)
1) If DTC P1765 is also set, go to DTC P1765: TRANS 12-VOLT
SUPPLY RELAY CNTRL CIRCUIT. If DTC P1765 is not set, go to next step.
2) If DTC SPECIFIC GOOD TRIPS counter is not displayed or
displayed count is not "0", go to step 16). If DTC SPECIFIC GOOD TRIPS
counter is displayed and displayed count is "0", go to next step.
3) Record freeze frame data to determine conditions when code
was set. Road test vehicle and reach a speed of 50 MPH. Depress
Overdrive (OD) switch 4 times so that vehicle attempts to shift from
4th gear to 3rd gear and back. If vehicle does not shift between 3rd
and 4th gear, go to next step. If vehicle shifts between 3rd and 4th
gear, go to step 16).
4) Turn ignition off. Disconnect transmission solenoid
harness connector. Inspect connector and terminals for damage. Repair
as necessary. If connector and terminals are okay, turn ignition on.
Using scan tool, actuate transmission control relay. Measure voltage
between ground and transmission relay output circuit at transmission
solenoid harness connector. If voltage does not switch from zero to
greater than 10 volts, go to step 13). If voltage switches from zero
to greater than 10 volts, go to next step.
5) Turn ignition off. Disconnect PCM harness connectors.
Inspect connectors and terminals for damage. Repair as necessary. If
connectors and terminals are okay, turn ignition on. Measure voltage
between ground and 3-4 shift solenoid control circuit at transmission
solenoid harness connector. If voltage is greater than 10 volts, go to
next step. If voltage is 10 volts or less, go to step 7).
6) Repair 3-4 shift solenoid control circuit for short to
voltage. Reconnect all disconnected harness connectors. Road test
vehicle and reach a speed of 50 MPH. Depress Overdrive (OD) switch 4
times so that vehicle attempts to shift from 4th gear to 3rd gear and
back. If vehicle does not shift between 3rd and 4th gear, replace PCM.
If vehicle shifts between 3rd and 4th gear, testing is complete.
7) Turn ignition off. Measure resistance between ground and
3-4 shift solenoid control circuit at White PCM harness connector C2.
If resistance is less than 5 ohms, repair short to ground in 3-4 shift
solenoid control circuit. If resistance is 5 ohms or greater, go to
next step.
8) Turn ignition off. Measure resistance between ground and
3-4 shift solenoid control circuit at White PCM harness connector C2.
If resistance is less than 5 ohms, repair short to ground in 3-4 shift
solenoid control circuit. If resistance is 5 ohms or greater, go to
next step.
9) Remove transmission control relay. Inspect transmission
control relay connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, measure resistance between
transmission control relay output circuit at transmission control
relay connector and 3-4 shift solenoid control circuit at White PCM
harness connector C2. If resistance is greater than 40 ohms, go to
next step. If resistance is 40 ohms or less, go to step 12).
10) Measure resistance between transmission control relay
output circuit at transmission control relay connector and 3-4 shift
solenoid control circuit at White PCM harness connector C2. If
resistance is 26-40 ohms, replace PCM. If resistance is not 26-40
ohms, go to next step.
11) Measure resistance of 3-4 shift solenoid circuit between
White PCM harness connector C2 and transmission solenoid harness

connector. If resistance is 5 ohms or greater, repair open 3-4 shift
solenoid circuit. If resistance is less than 5 ohms, replace
transmission solenoid and harness assembly.
12) Measure resistance between transmission control relay
output circuit at transmission control relay connector and 3-4 shift
solenoid control circuit at White PCM harness connector C2. If
resistance is 26-40 ohms, replace PCM. If resistance is not 26-40
ohms, test is complete.
13) Remove transmission control relay. Inspect transmission
control relay connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, turn ignition on. Measure voltage
between ground and fused B+ circuit at transmission control relay
connector. If voltage is 10 volts or less, repair open fused B+
circuit. If voltage is greater than 10 volts, go to next step.
14) Turn ignition off. Measure resistance of transmission
control relay output circuit at transmission control relay connector
and TCC solenoid harness connector. If resistance is greater than 5
ohms, repair open transmission control relay output circuit. If
resistance is 5 ohms or less, go to next step.
15) Measure resistance between ground and transmission
control relay output circuit at transmission solenoid harness
connector. If resistance is less than 5 ohms, repair short to ground
in transmission control relay output circuit. If resistance is 5 ohms
or greater, replace transmission control relay.
16) Using scan tool, erase DTCs. Start engine. Attempt to
duplicate data and reset code. Using wiring diagram as a guide,
inspect wiring and connectors. Repair wiring harness as necessary. If
wiring and connectors are okay, go to next step.
17) Wiggle wiring harness between TCC solenoid and PCM. Note
if DTC P0753 resets. If DTC P0753 resets, repair wiring harness as
necessary. If DTC P0753 does not reset, replace PCM and see INACTIVE
DTC CONDITION under SELF-DIAGNOSTIC SYSTEM. Testing is complete.
Diagnostic Procedure (WJ Body)
NOTE: If all solenoid codes, P0743, P0748 and P0753 are set, go to
test DTC P1765: TRANS 12-VOLT SUPPLY RELAY CNTRL CIRCUIT
before proceeding.
1) Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIPS
counter is not displayed or displayed count is not "0", go to next
step. If DTC SPECIFIC GOOD TRIPS counter is displayed and displayed
count is "0", go to step 16).
2) Road test vehicle and reach a speed of 50 MPH. Depress
Overdrive (OD) switch 4 times so that vehicle attempts to shift from
4th gear to 3rd gear and back. If vehicle does not shift between 3rd
and 4th gear, go to step 4). If vehicle shifts between 3rd and 4th
gear, go to next step.
3) Record freeze frame data to determine conditions when code
was set. Using wiring diagram as a guide, inspect wiring and
connectors. Repair wiring harness as necessary. If wiring and
connectors are okay, see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC
SYSTEM. Testing is complete.
4) Turn ignition off. Disconnect transmission solenoid
harness connector. Inspect connector and terminals for damage. Repair
as necessary. If connector and terminals are okay, turn ignition on.
Using scan tool, actuate transmission control relay. Measure voltage
between ground and transmission relay output circuit at transmission
solenoid harness connector. If voltage does not switch from zero to
greater than 10 volts, go to step 12). If voltage switches from zero
to greater than 10 volts, go to next step.
5) Turn ignition off. Disconnect PCM harness connectors.
Inspect connectors and terminals for damage. Repair as necessary. If

connectors and terminals are okay, measure resistance between ground
and 3-4 shift solenoid control circuit at PCM harness connector. If
resistance is 5 ohms or greater, go to next step. If resistance is
less than 5 ohms, repair short to ground in 3-4 shift solenoid
circuit.
6) Measure resistance of 3-4 shift solenoid circuit between
White PCM harness connector C2 and transmission solenoid harness
connector. If resistance is 5 ohms or greater, repair open 3-4 shift
solenoid circuit. If resistance is less than 5 ohms, go to next step.
7) Turn ignition on. Measure voltage between ground and 3-4
shift solenoid control circuit at PCM harness connector. If voltage is
greater than one volt, repair 3-4 shift solenoid control circuit for
short to voltage. If voltage is one volt or less, go to next step.
8) Turn ignition off. Remove transmission control relay.
Inspect transmission control relay connector and terminals for damage.
Repair as necessary. If connector and terminals are okay, measure
resistance between transmission control relay output circuit at
transmission control relay connector and 3-4 shift solenoid control
circuit at White PCM harness connector C2. If resistance is 26-40
ohms, go to next step. If resistance is not 26-40 ohms or less,
replace 3-4 shift solenoid.
9) Measure resistance between ground and transmission control
relay output circuit at transmission control relay connector. If
resistance is less than 5 ohms, repair short to ground in transmission
control relay output circuit. If resistance is 5 ohms or greater, go
to next step.
10) Measure resistance between transmission control relay
output circuit between transmission control relay connector and
transmission solenoid harness connector. If resistance is 5 ohms or
greater, repair open transmission control relay output circuit. If
resistance is less than 5 ohms, go to next step.
11) Turn ignition on. Measure voltage between ground and
fused B+ circuit at transmission control relay connector. If voltage
is 10 volts or less, repair open fused B+ circuit. If voltage is
greater than 10 volts, replace PCM.
12) Disconnect transmission control relay. Inspect connector
and terminals for damage. Repair as necessary. If connector and
terminals are okay, turn ignition on. Replace transmission control
relay. Using scan tool, actuate transmission control relay. Measure
voltage between ground and transmission relay output circuit at
transmission solenoid harness connector. If voltage is greater than 10
volts, replace transmission control relay. If voltage is 10 volts or
less, go to next step.
13) Measure resistance of transmission control relay output
circuit between transmission control relay connector solenoid harness
connector. If resistance is 5 ohms or greater, repair open in
transmission control relay output circuit. If resistance is less than
5 ohms, go to next step.
14) Measure resistance of transmission control relay output
circuit between ground and transmission control relay connector. If
resistance is 5 ohms or greater, go to next step. If resistance is
less than 5 ohms, repair short to ground in transmission control relay
output circuit.
15) Turn ignition on. Measure voltage between ground and
fused B+ circuit at transmission control relay connector. If voltage
is 10 volts or less, repair open fused B+ circuit. If voltage is
greater than 10 volts, test is complete.
16) Using scan tool, erase DTCs. Start engine. Attempt to
duplicate data and reset code. Using wiring diagram as a guide,
inspect wiring and connectors. Repair wiring harness as necessary. If
wiring and connectors are okay, wiggle wiring harness between TCC
solenoid and PCM. Note if DTC P0753 resets. If DTC P0753 resets,
repair wiring harness as necessary. If DTC P0753 does not reset,

replace PCM and see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC
SYSTEM. Testing is complete.
DTC P0783: 3-4 SHIFT SOL, NO RPM DROP @ 3-4 SHIFT
Circuit Description
Circuit is monitored continuously while key is on and engine
running. Code sets if expected RPM drop does not occur within 4
seconds of requested gear change by PCM. Test must fail 3 times to set
code.
Possible Causes
* Transmission mechanically defective.
* TPS codes set.
* Transmission 3-4 solenoid wiring harness defective.
* Transmission fluid burnt or oil pan has excessive debris.
Diagnostic Procedures
1) Using scan tool, read DTCs. On all bodies except AB and WJ
bodies, go to next step. On AB and WJ bodies, if DTC SPECIFIC GOOD
TRIPS counter is not displayed or displayed count is not "0", go to
step 6). If DTC SPECIFIC GOOD TRIPS counter is displayed and displayed
count is "0", indicating DTC still exists, go to next step.
2) If any DTCs listed are present, perform appropriate
test(s). See 3-4 SHIFT SOLENOID TESTS table. If no DTCs are present,
go to next step.
3-4 SHIFT SOLENOID TESTS









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DTC Message Test
NO CAM SIGNAL AT PCM ..................................... ( 1) P0340
P/N SWITCH STUCK IN PARK OR IN GEAR .......................... P1899
Any Throttle Position Sensor (TPS) DTC ......................... ( 1)
TORQUE CONVERTOR CLUTCH SOLENOID/TRANS RELAY CIRCUITS ........ P0743
TRANS 12-VOLT SUPPLY RELAY CNTRL CIRCUIT ..................... P1765
TRANS 3-4 SHIFT SOLENOID/TRANS RELAY CIRCUITS ................ P0753
( 1) - See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.









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3) Check transmission fluid for proper level and for any
debris. Fill or repair transmission as necessary. If fluid level and
condition are okay, go to next step.
4) Connect a 0-300 psi (0-21 kg/cm
) pressure gauge to
transmission Overdrive (O/D) clutch pressure test port. Connect a
second 0-300 psi (0-21 kg/cm
) pressure gauge to transmission governor
pressure test port. See appropriate AUTOMATIC TRANSMISSION OVERHAUL
article. Ensure engine and transmission are at normal operating
temperature. With an assistant, test drive vehicle. Using scan tool,
select GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 4th gear while
monitoring pressure gauge. Governor pressure should rise to greater
than 20 psi (1.4 kg/cm
) and O/D pressure should rise to greater than
40 psi (2.8 kg/cm). If pressures are as specified, go to next step.
If pressures are not as specified, go to step 8).
5) Using wiring diagram as a guide, inspect wiring and
connectors. Repair wiring harness as necessary. If wiring and
connectors are okay, go to next step.
6) Using scan tool, erase DTCs. Start engine. Road test
vehicle at 0-55 MPH with a constant 20 percent throttle. Repeat road
test 4 times. Note if DTC P0783 resets. If DTC P0783 resets, repair
wiring harness as necessary. If DTC P0783 does not reset, go to next