DTC Troubleshooting: C1840-12 (47-01)
DTC C1840-12: Differential Fluid Pressure Sensor Circuit High Voltage
NOTE: Before you troubleshoot, review the General Troubleshooting Information.

DTC Description
DTC
Freeze Frame
C1840-12 Differential Fluid Pressure Sensor Circuit High Voltage
    

1.
Determine possible failure area (electrical circuit problem, hydraulic circuit problem):

Determine possible failure area (electrical circuit problem, hydraulic circuit problem)
?1.
Start the engine.

?2.
Check the parameter(s) below with the HDS.
Signal
Threshold
Current conditions
Values
Unit
Values
Unit
Voltage of the oil pressure sensor for rear differential
More than 4.14
V
    

Do the current condition(s) match the threshold?

     
YES
     
     
     
Go to step 3.
     
NO
     
     
     
Go to step 2.
2.
Problem verification:

Problem verification
?1.
Clear the DTC with the HDS.


?2.
Turn the vehicle to the OFF (LOCK) mode.

?3.
Turn the vehicle to the ON mode.

?4.
Select the FUNCTIONAL TEST in the REAL TIME AWD with the HDS.

?5.
Do the OIL PRESSURE CONTROL TEST in the FUNCTIONAL TEST with the HDS.

  

Is the test result OK?

     
YES
     
     
     
Intermittent failure, the system is OK at this time. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot.?
     
NO
     
     
     
3.
Determine possible failure area (short to power in PS1 line, others):

Determine possible failure area (short to power in PS1 line, others)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the following connector.
Rear differential fluid pressure sensor 3P connector

?3.
Turn the vehicle to the ON mode.

?4.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle ON mode
 
Rear differential fluid pressure sensor 3P connector: disconnected
Test point 1
Rear differential fluid pressure sensor 3P connector (female terminals) No. 1:
Test point 2
Rear differential fluid pressure sensor 3P connector (female terminals) No. 2:


Is there about 4.14 V or more?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
Go to step 7.
4.
Shorted wire check (PS1 line to power):

Shorted wire check (PS1 line to power)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the following connector.
AWD control unit 24P connector

?3.
Turn the vehicle to the ON mode.

?4.
Measure the voltage between test points 1 and 2.
Test condition
Vehicle ON mode
 
Rear differential fluid pressure sensor 3P connector: disconnected
 
AWD control unit 24P connector: disconnected
Test point 1
Rear differential fluid pressure sensor 3P connector (female terminals) No. 2:
Test point 2
Body ground


Is there about 0.5 V or more?

     
YES
     
     
     
Repair a short to power in the PS1 wire between the rear differential fluid pressure sensor and the AWD control unit.?
     
NO
     
     
     
Go to the 5.
5.
Shorted wire check (PS1 line to SVCC line):

Shorted wire check (PS1 line to SVCC line)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Rear differential fluid pressure sensor 3P connector: disconnected
 
AWD control unit 24P connector: disconnected
Test point 1
Rear differential fluid pressure sensor 3P connector (female terminals) No. 2:
Test point 2
Rear differential fluid pressure sensor 3P connector (female terminals) No. 3:


Is there continuity?

     
YES
     
     
     
Repair a short in the PS1 wire to the SVCC wire between the rear differential fluid pressure sensor and the AWD control unit.?
     
NO
     
     
     
Go to step 6.
6.
Rear differential fluid pressure sensor check:

Rear differential fluid pressure sensor check
?1.
Connect the following connector.
AWD control unit 24P connector

?2.
Connect terminals A and B with a jumper wire.
Terminal A
Rear differential fluid pressure sensor 3P connector (female terminals) No. 1:
Terminal B
Rear differential fluid pressure sensor 3P connector (female terminals) No. 2:


?3.
Turn the vehicle to the ON mode.

?4.
Check the parameter(s) below with the HDS.
Signal
Threshold
Current conditions
Values
Unit
Values
Unit
Voltage of the oil pressure sensor for rear differential
Less than 0.1
V
    

Do the current condition(s) match the threshold?

     
YES
     
     
     
     
NO
     
     
     
Check for any authorized service information related to the DTCs or symptoms you are troubleshooting or substitute a known-good AWD control unit, and recheck. If the symptom/indication goes away with a known-good AWD control unit, replace the original AWD control unit.?
7.
Determine possible failure area (open in PS1 line, others):

Determine possible failure area (open in PS1 line, others)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Connect terminals A and B with a jumper wire.
Terminal A
Rear differential fluid pressure sensor 3P connector (female terminals) No. 2:
Terminal B
Body ground


?3.
Turn the vehicle to the ON mode.

?4.
Check the parameter(s) below with the HDS.
Signal
Threshold
Current conditions
Values
Unit
Values
Unit
Voltage of the oil pressure sensor for rear differential
Less than 0.1
V
    

Do the current condition(s) match the threshold?

     
YES
     
     
     
Go to step 9.
     
NO
     
     
     
Go to step 8.
8.
Open wire check (PS1 line):

Open wire check (PS1 line)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Remove the jumper wire.

?3.
Disconnect the following connector.
AWD control unit 24P connector

?4.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Rear differential fluid pressure sensor 3P connector: disconnected
 
AWD control unit 24P connector: disconnected
Test point 1
Rear differential fluid pressure sensor 3P connector (female terminals) No. 2:
Test point 2
AWD control unit 24P connector No. 21


Is there continuity?

     
YES
     
     
     
Check for any authorized service information related to the DTCs or symptoms you are troubleshooting or substitute a known-good AWD control unit, and recheck. If the symptom/indication goes away with a known-good AWD control unit, replace the original AWD control unit.?
     
NO
     
     
     
Repair an open in the PS1 wire between the rear differential fluid pressure sensor and the AWD control unit.?
9.
Open wire check (SG line):

Open wire check (SG line)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Remove the jumper wire.

?3.
Disconnect the following connector.
AWD control unit 24P connector

?4.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
 
Rear differential fluid pressure sensor 3P connector: disconnected
 
AWD control unit 24P connector: disconnected
Test point 1
Rear differential fluid pressure sensor 3P connector (female terminals) No. 1:
Test point 2
Real time AWD control unit 24P connector No. 11


Is there continuity?

     
YES
     
     
     
Check for any authorized service information related to the DTCs or symptoms you are troubleshooting or substitute a known-good AWD control unit, and recheck. If the symptom/indication goes away with a known-good AWD control unit, replace the original AWD control unit.?
     
NO
     
     
     
Repair an open in the SG wire between the rear differential fluid pressure sensor and the AWD control unit.?