relay DODGE RAM 1999 Service User Guide

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Fig. 2: Identifying Compressor Clutch Relay Terminals (Typical)
Courtesy of Chrysler Corp.
BLOWER MOTOR RESISTOR
1) Disconnect negative battery cable. Disconnect blower motor
resistor harness connector. Using an ohmmeter, check for continuity
between all 4 front blower motor resistor terminals, or 3 rear blower
motor resistor terminals. If continuity exists, go to next step. If
continuity does not exist, replace faulty blower motor resistor.
2) Check for open or short in circuits between blower motor
resistor and A/C-heater control panel. Also check for open or short in
wire between blower motor resistor and blower motor.
BLOWER MOTOR SWITCH
Front
1) Using a voltmeter, check underhood power distribution
center for battery voltage at fuse No. 5 (40-amp) on Dakota and
Durango, or fuse No. 5 (40-amp) on Ram Pickup. If battery voltage
exists, go to next step. If battery voltage does not exist, check for
open in Red wire between battery and underhood power distribution
center. If Red wire is okay, replace underhood power distribution
center.
2) Disconnect negative battery cable. Remove A/C-heater
control panel. See A/C-HEATER CONTROL PANEL R & I . Disconnect A/C-
heater control panel harness connector. Using an ohmmeter, check for
continuity between A/C-heater control panel harness connector terminal
No. 7 (Black wire on Dakota and Durango; Black/Orange on Ram Pickup)
and ground. If continuity exists, go to step 4).
3) If continuity does not exist, repair open in Black or
Black/Orange wire between A/C-heater control panel harness connector
terminal No. 7 and ground connector located at lower right corner of
instrument panel (Dakota and Durango) or behind center of instrument
panel (Ram Pickup).
4) Place mode control knob to any position except OFF. Using
an ohmmeter, check for continuity between A/C-heater control panel
connector terminal No. 7 and terminals No. 3, 4, 5, and 6 while
rotating blower motor switch. See Fig. 3.
5) If continuity does not exist at any terminal, replace
faulty A/C-heater control panel. If continuity exists as specified,
check for open in circuits between A/C-heater control panel and blower
motor resistor. Also check for an open in circuit between A/C-heater

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control panel and blower motor.
Fig. 3: Identifying Blower Motor Switch Connector Terminals (Typical)\
Courtesy of Chrysler Corp.
Rear (Durango)
1) Disconnect negative battery cable. Remove rear blower
motor switch located in headliner. See BLOWER MOTOR SWITCH (REAR)
under REMOVAL & INSTALLATION. Disconnect rear blower motor switch
connector. Using an ohmmeter, check continuity between rear blower
motor switch connector Black wire and ground. If continuity exists, go
to next step. If continuity does not exist, repair open in Black wire
between rear blower motor switch connector and ground connector
located at left rear of vehicle body.
2) Place blower motor switch knob to any position except OFF.
Using an ohmmeter, check for continuity between rear blower motor
switch connector Black wire and Black/Light Blue wire, and
Black/Orange wire and Dark Green wire while rotating blower motor
switch.
3) If continuity does not exist at any terminal, replace
faulty blower motor switch. If continuity exists as specified, check
for open in circuits between blower motor switch and blower motor
resistor. Also check for an open in circuit between blower motor
switch connector and blower motor relay.
CLUTCH CYCLING PRESSURE SWITCH
Dakota & Ram Pickup
1) Locate clutch cycling pressure switch on side or top of
A/C accumulator. Ensure clutch cycling pressure switch is properly
installed on A/C accumulator fitting. Ensure system pressure is
correct. See A/C SYSTEM PERFORMANCE test.
2) Start and run engine with A/C on. If clutch cycles, turn
engine off and disconnect negative battery cable. Disconnect clutch
cycling pressure switch connector. Place a jumper wire across
terminals of clutch cycling pressure switch harness connector. Connect
negative battery cable. Connect manifold gauge set. Set A/C-heater

Page 118 of 1691


A/C -H EA TE R S YSTE M T R O UBLE S H O OTIN G

1999 D odge P ic ku p R 1500
1999 MANUAL A/C-HEATER SYSTEMS
Trouble Shooting - Cars & Trucks
CHRYSLER
Avenger, Breeze, Caravan, Cirrus, Concorde, Dakota, Durango,
Intrepid, LHS, Neon, Ram Pickup, Ram Van/Wagon, Sebring Convertible,
Sebring Coupe, Stratus, Town & Country, Voyager, 300M
A/C SYSTEM DIAGNOSIS
RAPID COMPRESSOR CLUTCH CYCLING
Some possible causes of rapid compressor clutch cycling,
clutch cycles 10 or more times per minute, include:
* Low refrigerant system charge.
* Faulty low pressure cycling clutch switch.
* Faulty PCM.
COMPRESSOR WILL NOT ENGAGE
Some possible causes of compressor not engaging with high and
low side system pressures equal include:
* No refrigerant in system.
* Faulty fuse.
* Faulty compressor clutch coil.
* Faulty compressor clutch relay.
* Faulty electronic cycling clutch switch.
* Improperly installed or faulty low pressure cycling clutch
switch.
* Faulty low pressure cut-off switch.
* Faulty high pressure cut-off switch.
* Faulty PCM.
* Faulty A/C-heater control panel.
TEMPERATURE IS TOO HIGH WITH A/C ON
Some possible causes of high temperature output at center
panel when A/C system pressure is normal include:
* Excessive oil charge in refrigerant.
* Temperature control cable improperly installed or faulty.
* Blend-air door inoperative, obstructed or sealing
improperly.
* Blend door actuator not calibrated.
LOW SIDE PRESSURE IS LOW-TO-NORMAL & HIGH SIDE PRESSURE IS
LOW
Some possible causes of low side system pressure being lower-
to-normal and high side system pressure being too low include:
* Low refrigerant system charge.
* Refrigerant flow through accumulator is restricted.
* Refrigerant flow through evaporator is restricted.
* Faulty compressor.
LOW SIDE PRESSURE IS HIGH-TO-NORMAL & HIGH SIDE PRESSURE IS

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HIGH
Some possible causes of low side system pressure being high-
to-normal and high side system pressure being too high include:
* Condenser air flow restricted.
* Inoperative cooling fan.
* Faulty expansion valve.
* Refrigerant system overcharged.
* Air in refrigerant system.
* Engine overheating.
LOW SIDE PRESSURE IS HIGH & HIGH SIDE PRESSURE IS LOW
Some possible causes of low side system pressure being too
high and high side system pressure being too low include:
* Compressor belt is slipping.
* Fixed orifice tube not installed.
* Faulty compressor.
LOW SIDE PRESSURE IS LOW & HIGH SIDE PRESSURE IS HIGH
Some possible causes of low side system pressure being too
low and high side system pressure being too high include:
* Restricted refrigerant flow through refrigerant lines.
* Restricted refrigerant flow through expansion valve.
* Restricted refrigerant flow through fixed orifice tube.
* Restricted refrigerant flow through receiver-drier.
* Restricted refrigerant flow through condenser.
BLOWER MOTOR DIAGNOSIS
BLOWER MOTOR INOPERATIVE
Some possible causes of an inoperative blower motor include:
* Faulty fuse.
* Faulty blower motor feed circuit wire harness or
connectors.
* Faulty blower motor ground circuit wire harness or
connector.
* Faulty blower motor resistor.
* Faulty blower motor relay.
* Faulty blower motor switch.
* Faulty A/C-heater mode control switch.
* Faulty blower motor.
BLOWER NOT OPERATING IN ALL SPEEDS
Possible causes of the blower not operating in all speeds
include:
* Faulty fuse.
* Faulty blower motor feed circuit wire harness or
connectors.
* Faulty blower motor relay.
* Faulty blower motor resistor.
* Faulty blower motor switch.

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CTM has remote keyless entry receiver and control logic incorporated.
COMPONENT TESTS
RELAYS
NOTE: Headlight relay may also be referred to as the security
relay. On Ram Pickup, the headlight relay is located in Power
Distribution Center (PDC) in engine compartment. On Ram Van
and Ram Wagon, the headlight relay is taped to headlight
switch harness. On Ram Pickup, the horn relay is located in
Power Distribution Center (PDC) in engine compartment. On Ram\
Van and Ram Wagon, the horn relay is located in junction
block under left side of instrument panel. For circuit
testing, see WIRING DIAGRAMS.
Headlight Relay & Horn Relay
Remove relay to be tested. Measure resistance between
appropriate relay terminals with relay de-energized and energized. See
RELAY TEST SPECIFICATIONS table. See Fig. 1. If continuity or
resistance is not as specified, replace relay.
RELAY TEST SPECIFICATIONS
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Terminals Condition
De-Energized
87A & 30 .............................................. Continuity
87 & 30 ............................................ No Continuity
85 & 86 .................................... 70-80 Ohms Resistance
Energized ( 1)
87 & 30 ............................................... Continuity
87A & 30 ........................................... No Continuity
( 1) - Apply position battery voltage to terminal No. 85 and ground
terminal No. 86.
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Fig. 1: Identifying Relay Connector Terminals
Courtesy of Chrysler Corp.
SYSTEM TESTS

Page 223 of 1691

Box (DRB) scan tool with appropriate cartridge for system
diagnosis. Other after-market scan tools may be used for
system diagnosis. The following procedure is for DRB scan
tool usage. Use scan tool manufacturer's instruction for
operating scan tool.
NOTE: Ensure battery is fully charged before proceeding with test.
1) Ensure ignition is off. Connect DRB to Data Link Connector
(DLC) located under driver's side of instrument panel. Using scan
tool, display all Diagnostic Trouble Codes (DTCs). Identify DTCs once
retrieved. See DIAGNOSTIC TROUBLE CODES (DTC) & DRB MESSAGES table.
2) If scan tool will not power up, check for loose cable
connections or faulty cable. If cable connections and cable are okay,
check voltage at DLC terminal No. 16. Voltage should be at least 11
volts. If voltage is not as specified, check wiring circuit and
necessary fuses. See WIRING DIAGRAMS.
3) If scan tool displays an error message, RAM TEST FAILURE,
CARTRIDGE ERROR, KEY PAD TEST FAILURE, or LOW OR HIGH BATTERY, this
indicates a scan tool failure.
4) If DTCs are displayed, perform appropriate test(s). See
DIAGNOSTIC TROUBLE CODES (DTC) & DRB MESSAGES table. If no DTCs are
displayed, see TROUBLE SHOOTING in appropriate AUTOMATIC TRANSMISSION
OVERHAUL article.
DIAGNOSTIC TROUBLE CODES (DTC) & DRB MESSAGES
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DTC DRB-III Scan Tool Message
P0711 .................. TRANS TEMP SENSOR, NO TEMP RISE AFTER START
P0712 ............................. TRANS TEMP SENSOR VOLTAGE TO LOW
P0713 ............................ TRANS TEMP SENSOR VOLTAGE TO HIGH
P0720 ..................... LOW OUTPUT SPEED SENSOR RPM ABOVE 15 MPH
P0740 .................... TORQ CONVERTER CLU, NO RPM DROP AT LOCKUP
P0743 ........ TORQUE CONVERTER CLUTCH SOLENOID/TRANS RELAY CIRCUITS
P0748 ........... GOVERNOR PRESSURE SOL CONTROL/TRANS RELAY CIRCUITS
P0751 ....................... OD SWITCH PRESSED (LO) MORE THAN 5 MIN\
P0753 ................ TRANS 3-4 SHIFT SOLENOID/TRANS RELAY CIRCUITS
P0783 ....................... 3-4 SHIFT SOL, NO RPM DROP @ 3-4 SHIFT
P1740 (1) .......................... TCC OR O/D SOLENOID PERFORMANCE
P1756 .................... GOV PRESS NOT EQUAL TO TARGET @ 15-20 PSI
P1757 ...................... GOV PRES ABOVE 3 PSI IN GEAR WITH 0 MPH
P1762 .................... GOV PRESS SEN OFFSET VOLTS TO LOW OR HIGH
P1763 ....................... GOVERNOR PRESSURE SENSOR VOLTS TO HIGH
P1763B ...................... GOVERNOR PRESSURE SENSOR VOLTS TO HIGH
P1764 ........................ GOVERNOR PRESSURE SENSOR VOLTS TO LOW
P1765 ..................... TRANS 12 VOLT SUPPLY RELAY CNTRL CIRCUIT
P1899 .......................... P/N SWITCH STUCK IN PARK OR ON GEAR
( 1) - BR body only.
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CLEARING DIAGNOSTIC TROUBLE CODES
After repairs have been performed, clear DTCs from PCM memory
using scan tool, following scan tool manufacturer's instructions.
NOTE: If malfunction is no longer present after DTC is stored in
PCM memory, the PCM will erase DTC after ignition has been
cycled at least 50 times. DTC may be cleared by using scan
tool. Follow scan tool manufacturer's instructions. DTCs may
also be cleared by disconnecting negative battery cable for a
period of time, but other vehicle control modules may also be

Page 224 of 1691

affected.
INACTIVE DTC CONDITION
This procedure applies if you have been sent here from a
diagnostic test and/or have just attempted to simulate the condition
that initially set the DTC. The following additional checks may assist
in identifying a possible intermittent problem:
* Visually inspect related wiring harness connectors for
broken, bent, pushed out or corroded terminals.
* Visually inspect related wiring harnesses for chafed, pierced
or partially broken wires.
* Check for Technical Service Bulletins (TSBs) relating to the
problem.
NOTE: For circuit description and wire color information, see
WIRING DIAGRAMS.
CONNECTOR IDENTIFICATION
CONNECTOR IDENTIFICATION DIRECTORY\
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Connector Figure
Data Link Connector (DLC) ............................... See Fig. 2
Overdrive (O/D) Off Switch
AN, BR & DN Bodies .................................... See Fig. 3
WJ Body ............................................... See Fig. 4
Park/Neutral Position (PNP) Switch ...................... See Fig. 5
Powertrain Control Module (PCM) ......................... See Fig. 6
Transmission Control Relay
AB Body ............................................... See Fig. 7
AN, BR, DN & WJ Bodies ................................ See Fig. 8
Transmission Governor Pressure Sensor ................... See Fig. 9
Transmission Output Shaft Speed Sensor
AB, BR & WJ - 4.0L Bodies ............................ See Fig. 10
AN & DN Bodies ....................................... See Fig. 11
Transmission Solenoid .................................. See Fig. 12
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Page 228 of 1691

Fig. 7: Identifying Transmission Control Relay Connector
Terminals (AB Body)
Courtesy of DaimlerChrysler Corp.
Fig. 8: Identifying Transmission Control Relay Connector
Terminals (AN, BR, DN & WJ Bodies)
Courtesy of DaimlerChrysler Corp.

Page 236 of 1691

2) If any DTCs listed are present, perform appropriate
test(s). See TORQUE CONVERTOR CLUTCH (TCC) TESTS table. If no DTCs a\
re
present, go to next step.
TORQUE CONVERTOR CLUTCH (TCC) TESTS
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DTC DTC Message
P0122 (1) ................. THROTTLE POSITION SENSOR VOLTAGE TOO LOW
P0123 ( 1) ................ THROTTLE POSITION SENSOR VOLTAGE TOO HIGH
P1696 ( 1) .......................... PCM FAILURE EEPROM WRITE DENIED
P0743 ........ TORQUE CONVERTOR CLUTCH SOLENOID/TRANS RELAY CIRCUITS
( 2) ........................................................ MISFIRE
P0320 ( 1) ......................... NO CRANK REFERENCE SIGNAL AT PCM
( 1) - See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
( 2) - Perform appropriate misfire DTC test. 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) Start engine. Using scan tool, perform TCC SYSTEM TEST. If
vehicle does not stall, go to step 9). If vehicle stalls, go to next
step.
5) Using scan tool, perform GOV and 3-4 SHIFT VALVE SYSTEM
TEST. Select 4th gear. If vehicle stalls, go to next step. If vehicle
does not stall, go to step 7).
6) Turn ignition off. Replace TCC solenoid. Using scan tool,
perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 4th gear. If
vehicle stalls, problem in internal. Check for blocked passage. If
vehicle does not stall, testing is complete.
7) Turn ignition off. Remove oil pump and inspect reaction
shaft, input shaft and input seal. Repair transmission as necessary.
See appropriate AUTOMATIC TRANSMISSION OVERHAUL article. If
transmission is okay, go to next step.
8) 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.
9) Turn ignition off. Connect a pressure gauge to
transmission cooler OUT port. Start engine. Using scan tool, perform
TCC SYSTEM TEST. If pressure increases when TCC is actuated, go to
next step. If pressure does not increase, repair leaks or blockage in
hydraulic circuit, or repair valve body as necessary.
10) Turn engine off. Remove oil pump and inspect reaction
shaft, input shaft and input seal. Repair transmission as necessary.
See appropriate AUTOMATIC TRANSMISSION OVERHAUL article. If
transmission is okay, there are no other potential causes remaining.
TCC is assumed to be defective. Replace torque converter.
DTC P0743: TORQUE CONV CLUTCH SOLENOID/TRANS RELAY CKT
NOTE: To test transmission temperature sensor, engine and
transmission temperature must be less than 85F (29C).
Circuit Description
Circuit is monitored continuously while key is on. Code sets
if voltage detected on Torque Converter Clutch (TCC) at the Powertrain\
Control Module (PCM) does not match desired voltage.
Possible Causes

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* Fused B+ feed to transmission control circuit open.
* Transmission control relay defective.
* TCC solenoid control circuit open.
* TCC solenoid control circuit shorted to ground.
* TCC wire harness defective.
* Transmission control relay output circuit open.
* Transmission control relay output circuit shorted to
ground.
* PCM defective.
* Solenoid and harness assembly defective.
Diagnostic Procedure (AN & DN Bodies)
1) Using scan tool, read DTCs. 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.
2) Using scan tool, perform TCC SYSTEM TEST. If engine
stalls, go to next step. If engine does not stall, go to step 5).
3) Using scan tool, clear DTCs. Start engine and check for
DTCs. Wiggle wiring harness between transmission harness connector and
PCM. If DTC P0743 resets, repair wiring harness as necessary. If DTC
P0743 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. 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 control relay output circuit at
transmission solenoid harness connector. If voltage does not cycle
from zero to greater than 10 volts, go to step 19). If voltage cycles
from zero to greater than 10 volts, go to next step.
6) Turn ignition off. Disconnect White PCM harness connector
C2. Inspect connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, turn ignition on. Measure voltage
between ground and TCC 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 TCC solenoid control circuit for short to voltage.
Reconnect PCM and transmission solenoid harness connector. Start
engine. Using scan tool, perform TCC SYSTEM TEST. If engine stalls,
testing complete. If engine does not stall, replace PCM.
8) Reconnect transmission solenoid harness connector. Remove
transmission control relay. Inspect 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 TCC solenoid control
circuit at White PCM harness connector C2. If resistance is 40 ohms or
less, go to step 12). If resistance is greater than 40 ohms, go to
next step.
9) Reconnect transmission control relay. Measure resistance
between ground and TCC solenoid control circuit at White PCM harness
connector C2. If resistance is less than 5 ohms, repair or replace
transmission solenoid and harness assembly. If resistance is 5 ohms or
greater, go to next step.
10) Remove transmission control relay. Measure resistance
between transmission control relay output circuit at transmission
control relay connector and TCC 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) Turn ignition off. Disconnect transmission solenoid
harness connector. Measure resistance of TCC solenoid control circuit

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