Circuit ISUZU KB P190 2007 Workshop Repair Manual

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-71
DTC P1750 (Flash Code 51)
Circuit Description
The low & reverse brake transmission fluid pressure
(TFP) switch is installed to the lower part of the valve
body assembly and it feedbacks fluid pressure in the
low & reverse brake hydraulic circuit. The low & reverse
brake fail-safe spool valves are installed to the control
valve body assembly and it uses to prevent interlocking
of clutches and brakes. When the solenoid valve is
energized, fluid pressure is drained to disengage the
low & reverse brake and the TFP switch is OFF. When
the solenoid valve is not energized, fluid pressure is
applied to engage the low & reverse brake and the TFP
switch is ON. The TCM monitors the low & reverse
brake TFP switch ON/ OFF status through the signal
circuit. If the TCM detects an improper status on the
signal circuit, this DTC will set.
Condition for Running the DTC • The ignition switch is ON.
Condition for Setting the DTC • The TCM detects that the low & reverse brake TFP switch signal repeats OFF/ ON twice when the
selector lever in forward range with the 2nd, 3rd or
4th gear.
Action Taken When the DTC Sets • The TCM blinks the Check Trans lamp when the diagnostic runs and fails. During the vehicle running;
• The TCM holds the last gear position when the diagnostic runs and fails.
• The TCM inhibits lock up control.
After the vehicle stopped;
• The TCM fixes to the 3rd gear.
Condition for Clearing the DTC • The TCM turns OFF the Check Trans lamp when the diagnostic runs and does not fail at next
ignition cycle.
• A current DTC clears when the diagnostic runs and does not fail at next ignition cycle.
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
• Use the Clutch, Brake, Solenoid and Pressure Switch Logic table to verify each component works
properly within the selected gear range.
• A sticking or intermittently sticking the low & reverse brake solenoid valve will cause this DTC to
set.
Schematic Reference: Transmission Controls
Schematics
Connector End View Reference: Transmission
Controls Connector End Views or TCM Connector End
Views
Circuit/ System Testing DTC P1750
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Transmission Controls? —
Go to Step 2 Go to Diagnostic
System Check -
Transmission Controls
2 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Lift the driving wheels or drive the vehicle while observing the DTC Information with a
scan tool.
Is DTC P0753 or P1853 also set? —
Go to Applicable DTC Go to Step 3
3 Place the selector lever in forward range while
observing the Low & Reverse Brake Pressure
Switch parameter with a scan tool.
Does the Low & Reverse Brake Pressure Switch
parameter ever indicate ON when gear is shifted
between 1st and 4th? —
Go to Step 4 Go to Diagnostic
Aids

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ISUZU KB P190 2007

7A2-72 TRANSMISSION CONTROL SYSTEM (JR405E)
41. Remove the transmission oil pan. Refer to
repair instructions (On-Vehicle Service).
2. Inspect the low & reverse brake solenoid valve and transmission fluid pressure (TFP) switch
for the following conditions:
• Physical damage
• Loose or improper installation
3. Test the signal circuit between the low & reverse brake TFP switch and the in-line
harness connector (pin 12 of E-54 male side)
for a short to ground.
4. Repair the circuit(s) or replace as necessary.
Did you find and correct the condition? —
Go to Step 7 Go to Step 5
5 1. Remove the low & reverse brake solenoid
valve and TFP switch from the valve body
assembly and perform function check. Refer
to repair instructions (On-Vehicle Service).
2. Repair or replace as necessary.
Did you find and correct the condition? —
Go to Step 7 Go to Step 6
6 Repair or replace the valve body assembly. Refer
to repair instructions (On-Vehicle Service or Unit
Repair).
Did you complete the repair or replacement? —
Go to Step 7 —
7 1. Reconnect all previously disconnected
components or harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Drive the vehicle while observing the DTC Information with a scan tool.
Did the DTC fail this ignition? —
Go to Step 2 Go to Step 8
8 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No

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ISUZU KB P190 2007

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-73
DTC P1755 (Flash Code 52)
Circuit Description
The 2-4 brake transmission fluid pressure (TFP) switch
is installed to the lower part of the valve body assembly
and it feedbacks fluid pressure in the 2-4 brake
hydraulic circuit. The low & reverse brake fail-safe
spool valves are installed to the control valve body
assembly and it uses to prevent interlocking of clutches
and brakes. When the solenoid valve is energized, fluid
pressure is drained to disengage the 2-4 brake and the
TFP switch is OFF. When the solenoid valve is not
energized, fluid pressure is applied to engage the 2-4
brake and the TFP switch is ON. The TCM monitors the
2-4 brake TFP switch ON/ OFF status through the
signal circuit. If the TCM detects an improper status on
the signal circuit, this DTC will set.
Condition for Running the DTC • The ignition switch is ON.
Condition for Setting the DTC • The TCM detects that the 2-4 brake TFP switch signal repeats OFF/ ON twice when the selector
lever in forward range with the 3rd gear.
Action Taken When the DTC Sets • The TCM blinks the Check Trans lamp when the diagnostic runs and fails. During the vehicle running;
• The TCM holds the last gear position when the diagnostic runs and fails.
• The TCM inhibits lock up control.
After the vehicle stopped;
• The TCM fixes to the 3rd gear.
Condition for Clearing the DTC • The TCM turns OFF the Check Trans lamp when the diagnostic runs and does not fail at next
ignition cycle.
• A current DTC clears when the diagnostic runs and does not fail at next ignition cycle.
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
• Use the Clutch, Brake, Solenoid and Pressure Switch Logic table to verify each component works
properly within the selected gear range.
• A sticking or intermittently sticking the 2-4 brake solenoid valve will cause this DTC to set.
Schematic Reference: Transmission Controls
Schematics
Connector End View Reference: Transmission
Controls Connector End Views or TCM Connector End
Views
Circuit/ System Testing DTC P1755
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Transmission Controls? —
Go to Step 2 Go to Diagnostic
System Check -
Transmission Controls
2 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Lift the driving wheels or drive the vehicle while observing the DTC Information with a
scan tool.
Is DTC P0758or P1858 also set? —
Go to Applicable DTC Go to Step 3
3 Place the selector lever in forward range while
observing the 2-4 Brake Pressure Switch
parameter with a scan tool.
Does the 2-4 Brake Pressure Switch parameter
ever indicate ON when gear is positioned 1st and
3rd? —
Go to Step 4 Go to Diagnostic
Aids

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ISUZU KB P190 2007

7A2-74 TRANSMISSION CONTROL SYSTEM (JR405E)
41. Remove the transmission oil pan. Refer to
repair instructions (On-Vehicle Service).
2. Inspect the 2-4 brake solenoid valve and transmission fluid pressure (TFP) switch for
the following conditions:
• Physical damage
• Loose or improper installation
3. Test the signal circuit between the 2-4 brake TFP switch and the in-line harness connector
(pin 7 of E-54 male side) for a short to ground
4. Repair the circuit(s) or replace as necessary.
Did you find and correct the condition? —
Go to Step 7 Go to Step 5
5 1. Remove the 2-4 brake solenoid valve and TFP
switch from the valve body assembly and
perform function check. Refer to repair
instructions (On-Vehicle Service).
2. Repair or replace as necessary.
Did you find and correct the condition? —
Go to Step 7 Go to Step 6
6 Repair or replace the valve body assembly. Refer
to repair instructions (On-Vehicle Service or Unit
Repair).
Did you complete the repair or replacement? —
Go to Step 7 —
7 1. Reconnect all previously disconnected
components or harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Drive the vehicle while observing the DTC Information with a scan tool.
Did the DTC fail this ignition? —
Go to Step 2 Go to Step 8
8 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No

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ISUZU KB P190 2007

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-75
DTC P1853 (Flash Code 26)
Circuit Description
The low & reverse brake transmission fluid pressure
(TFP) switch is installed to the lower part of the valve
body assembly and it feedbacks fluid pressure in the
low & reverse brake hydraulic circuit. When the
solenoid valve is energized, fluid pressure is drained to
disengage the low & reverse brake and the TFP switch
is OFF. When the solenoid valve is not energized, fluid
pressure is applied to engage the low & reverse brake
and the TFP switch is ON. The TCM monitors the low &
reverse brake TFP switch ON/ OFF status through the
signal circuit. If the TCM detects an improper status on
the signal circuit, this DTC will set.
Condition for Running the DTC • DTCs P0560, P0705, P0717, P0722, P0753, P0758, P0763, P0768, P1120, P1750, P1755 and
P1875 are not set.
AND following conditions are met for longer than 2.5
seconds.
• The ignition switch is ON.
• The transmission fluid temperature is more than 60 °C (140 °F).
• The engine speed is more than 500 RPM.
• The TCM is not under gearshift control.
Condition for Setting the DTC
Either of following condition is met: • The TCM detects that the low & reverse brake TFP switch signal is stuck at the ON for longer than 2
seconds when the selector lever in D range with
4th gear. • The TCM detects that the low & reverse brake TFP
switch signal is stuck at the OFF for longer than 2
second when the selector lever in R range.
Action Taken When the DTC Sets • The TCM blinks the Check Trans lamp when the diagnostic runs and fails.
Condition for Clearing the DTC • The TCM turns OFF the Check Trans lamp when the diagnostic runs and does not fail.
• A current DTC clears when the diagnostic runs and does not fail.
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
• Use the Clutch, Brake, Solenoid and Pressure Switch Logic table to verify each component works
properly within the selected gear range.
• A sticking or intermittently sticking the low & reverse brake solenoid valve will cause this DTC to
set.
Schematic Reference: Transmission Controls
Schematics
Connector End View Reference: Transmission
Controls Connector End Views or TCM Connector End
Views
Circuit/ System Testing DTC P1853
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Transmission Controls? —
Go to Step 2 Go to Diagnostic
System Check -
Transmission Controls
2 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Lift the driving wheels or drive the vehicle while observing the DTC Information with a
scan tool.
Is DTC P0753 also set? —
Go to DTC P0753 Go to Step 3
3 Place the selector lever in forward range while
observing the Low & Reverse Brake Pressure
Switch parameter with a scan tool.
Does the Low & Reverse Brake Pressure Switch
parameter ever indicate ON when gear is shifted
between 1st and 4th? —
Go to Step 5 Go to Step 4

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ISUZU KB P190 2007

7A2-76 TRANSMISSION CONTROL SYSTEM (JR405E)
4Place the selector lever in R range while observing
the Low & Reverse Brake Pressure Switch
parameter with a scan tool.
Does the Low & Reverse Brake Pressure Switch
parameter indicate ON? —
Go to Diagnostic Aids Go to Step 5
5 1. Turn OFF the ignition.
2. Disconnect the in-line harness connector (E- 54) near the transmission range switch.
3. Turn ON the ignition, with the engine OFF.
4. Observe the Low & Reverse Brake Switch parameter with a scan tool while momentarily
jumping 3-amp fused jumper wire between pin
12 of E-54 (female side) and a known good
ground.
Does the scan tool indicate ON when the circuit is
jumpered and OFF when the circuit is not
jumpered? —
Go to Step 8 Go to Step 6
6 1. Test the signal circuit between the TCM (pin
12 of C-95) and the in-line harness connector
(pin 12 of E-54 female side) for the following
conditions:
• An open circuit
• A short to ground
• High resistance
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 7
7 1. Turn OFF the ignition.
2. Disconnect the TCM harness connector.
3. Inspect for an intermittent and for a poor connection at the harness connector of the
TCM (pin 12 of C-95).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 12
8 1. Inspect for an intermittent and for a poor
connection at the in-line harness connector
(pin 12 of E-54).
2. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 9
Step
Action Value(s)Yes No

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TO MODEL INDEX
ISUZU KB P190 2007

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-77
91. Remove the transmission oil pan. Refer to
repair instructions (On-Vehicle Service).
2. Inspect the low & reverse brake solenoid valve and transmission fluid pressure (TFP) switch
for the following conditions:
• Physical damage
• Loose or improper installation
3. Inspect for an intermittent and for a poor connection at the harness connector of the
low & reverse brake TFP switch or in-line
harness connector.
4. Test the signal circuit between the low & reverse brake TFP switch and the in-line
harness connector (pin 12 of E-54 male side)
for the following conditions:
• An open circuit
• A short to ground
• A short to the solenoid valve circuit
• High resistance
5. Repair the connection(s), circuit(s) or replace as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 10
10 1. Remove the low & reverse brake solenoid
valve and TFP switch from the valve body
assembly and perform function check. Refer
to repair instructions (On-Vehicle Service).
2. Repair or replace as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 11
11 Repair or replace the valve body assembly. Refer
to repair instructions (On-Vehicle Service or Unit
Repair).
Did you complete the repair or replacement? —
Go to Step 13 —
12 Important:
Replacement TCM must be
programmed.
Replace the TCM. Refer to TCM Replacement.
Did you complete the replacement? —
Go to Step 13 —
13 1. Reconnect all previously disconnected
components or harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Drive the vehicle while observing the DTC Information with a scan tool.
Did the DTC fail this ignition? —
Go to Step 2 Go to Step 14
14 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No

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TO MODEL INDEX
ISUZU KB P190 2007

7A2-78 TRANSMISSION CONTROL SYSTEM (JR405E)
DTC P1858 (Flash Code 27)
Circuit Description
The 2-4 brake transmission fluid pressure (TFP) switch
is installed to the lower part of the valve body assembly
and it feedbacks fluid pressure in the 2-4 brake
hydraulic circuit. When the solenoid valve is energized,
fluid pressure is drained to disengage the 2-4 brake
and the TFP switch is OFF. When the solenoid valve is
not energized, fluid pressure is applied to engage the
2-4 brake and the TFP switch is ON. The TCM
monitors the 2-4 brake pressure switch ON/ OFF status
through the signal circuit. If the TCM detects an
improper status on the signal circuit, this DTC will set.
Condition for Running the DTC • DTCs P0560, P0705, P0717, P0722, P0753, P0758, P0763, P0768, P1120, P1750, P1755 and
P1875 are not set.
AND following conditions are met for longer than 2.5
seconds.
• The ignition switch is ON.
• The transmission fluid temperature is more than 60 °C (140 °F).
• The engine speed is more than 500 RPM.
• The TCM is not under gearshift control.
Condition for Setting the DTC
Either of following condition is met: • The TCM detects that the 2-4 brake TFP switch signal is stuck at the ON for longer than 2 seconds
when the selector lever in P, R or N range. • The TCM detects that the 2-4 brake TFP switch
signal is stuck at the OFF for longer than 2 second
when the selector lever in D range with 4th gear.
Action Taken When the DTC Sets • The TCM blinks the Check Trans lamp when the diagnostic runs and fails.
Condition for Clearing the DTC • The TCM turns OFF the Check Trans lamp when the diagnostic runs and does not fail.
• A current DTC clears when the diagnostic runs and does not fail.
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
• Use the Clutch, Brake, Solenoid and Pressure Switch Logic table to verify each component works
properly within the selected gear range.
• A sticking or intermittently sticking the 2-4 brake solenoid valve will cause this DTC to set.
Schematic Reference: Transmission Controls
Schematics
Connector End View Reference: Transmission
Controls Connector End Views or TCM Connector End
Views
Circuit/ System Testing DTC P1858
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Transmission Controls? —
Go to Step 2 Go to Diagnostic
System Check -
Transmission Controls
2 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Lift the driving wheels or drive the vehicle while observing the DTC Information with a
scan tool.
Is DTC P0758 also set? —
Go to DTC P0758 Go to Step 3
3 Place the selector lever in forward range while
observing the 2-4 Brake Pressure Switch
parameter with a scan tool.
Does the 2-4 Brake Pressure Switch parameter
ever indicate OFF when gear is positioned 2nd and
4th? —
Go to Step 5 Go to Step 4

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ISUZU KB P190 2007

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-79
4Place the selector lever in P, R and N range while
observing the 2-4 Brake Pressure Switch
parameter with a scan tool.
Does the 2-4 Brake Pressure Switch parameter
indicate OFF? —
Go to Diagnostic Aids Go to Step 5
5 1. Turn OFF the ignition.
2. Disconnect the in-line harness connector (E- 54) near the transmission range switch.
3. Turn ON the ignition, with the engine OFF.
4. Observe the 2-4 Brake Switch parameter with a scan tool while momentarily jumping 3-amp
fused jumper wire between pin 7 of E-54
(female side) and a known good ground.
Does the scan tool indicate ON when the circuit is
jumpered and OFF when the circuit is not
jumpered? —
Go to Step 8 Go to Step 6
6 1. Test the signal circuit between the TCM (pin 1
of C-95) and the in-line harness connector (pin
7 of E-54 female side) for the following
conditions:
• An open circuit
• A short to ground
• High resistance
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 7
7 1. Turn OFF the ignition.
2. Disconnect the TCM harness connector.
3. Inspect for an intermittent and for a poor connection at the harness connector of the
TCM (pin 1 of C-95).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 12
8 1. Inspect for an intermittent and for a poor
connection at the in-line harness connector
(pin 7 of E-54).
2. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 9
Step
Action Value(s)Yes No

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TO MODEL INDEX
ISUZU KB P190 2007

7A2-80 TRANSMISSION CONTROL SYSTEM (JR405E)
91. Remove the transmission oil pan. Refer to
repair instructions (On-Vehicle Service).
2. Inspect the 2-4 brake solenoid valve and transmission fluid pressure (TFP) switch for
the following conditions:
• Physical damage
• Loose or improper installation
3. Inspect for an intermittent and for a poor connection at the harness connector of the 2-
4 brake TFP switch or in-line harness
connector.
4. Test the signal circuit between the 2-4 brake TFP switch and the in-line harness connector
(pin 7 of E-54 male side) for the following
conditions:
• An open circuit
• A short to ground
• A short to the solenoid valve circuit
• High resistance
5. Repair the connection(s), circuit(s) or replace as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 10
10 1. Remove the 2-4 brake solenoid valve and TFP
switch from the valve body assembly and
perform function check. Refer to repair
instructions (On-Vehicle Service).
2. Repair or replace as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 11
11 Repair or replace the valve body assembly. Refer
to repair instructions (On-Vehicle Service or Unit
Repair).
Did you complete the repair or replacement? —
Go to Step 13 —
12 Important:
Replacement TCM must be
programmed.
Replace the TCM. Refer to TCM Replacement.
Did you complete the replacement? —
Go to Step 13 —
13 1. Reconnect all previously disconnected
components or harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Drive the vehicle while observing the DTC Information with a scan tool.
Did the DTC fail this ignition? —
Go to Step 2 Go to Step 14
14 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007