DTC C1840-12 (47-01) (AWD) (2016 2017 2018)

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DTC C1840-12 : Differential Fluid Pressure Sensor Circuit High Voltage

NOTE: Before you troubleshoot, review the General Troubleshooting Information for the AWD with intelligent control system .

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

DTC (AWD)

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
Signal	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.

Go to step 2.

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

-2. Select FUNCTIONAL TEST in the AWD WITH INTELLIGENT CONTROL with the HDS.

-3. Do the OIL PRESSURE CONTROL TEST in the FUNCTIONAL TEST with the HDS .

Oil Pressure Control Test

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

The failure is duplicated. Follow the instructions indicated on the HDS according to the test result .

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 No. 1
Test point 2	Rear differential fluid pressure sensor 3P connector No. 2

Courtesy of HONDA, U.S.A., INC.

Is there about 4.14 V or more?

YES

Go to step 4.

Go to step 5.

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 No. 2
Test point 2	Body ground

Courtesy of HONDA, U.S.A., INC.

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.

Update the AWD control unit if it does not have the latest software , or substitute a known-good AWD control unit , and recheck. If the symptom/indication goes away with the updated AWD control unit, troubleshooting is complete. If the symptom/indication goes away with a known-good AWD control unit, replace the original AWD control unit .

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 No. 2
Terminal B	Body ground

Courtesy of HONDA, U.S.A., INC.

-3. Turn the vehicle to the ON mode.

-4. Check the parameter(s) below with the HDS.

Signal	Threshold		Current conditions
Signal	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 7.

Go to step 6.

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 No. 2
Test point 2	AWD control unit 24P connector No. 21

Courtesy of HONDA, U.S.A., INC.

Is there continuity?

YES

Repair an open in the PS1 wire between the rear differential fluid pressure sensor and the AWD control unit.

Rear differential fluid pressure sensor check

-1. Turn the vehicle to the OFF (LOCK) mode.

-2. Remove the jumper wire.

-3. Connect terminals A and B with a jumper wire.

Terminal A	Rear differential fluid pressure sensor 3P connector No. 1
Terminal B	Rear differential fluid pressure sensor 3P connector No. 2

Courtesy of HONDA, U.S.A., INC.

-4. Turn the vehicle to the ON mode.

-5. Check the parameter(s) below with the HDS.

Signal	Threshold		Current conditions
Signal	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

Replace the rear differential fluid pressure sensor .

The rear differential fluid pressure sensor is OK. Go to step 8.

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 No. 1
Test point 2	AWD control unit 24P connector No. 11

Courtesy of HONDA, U.S.A., INC.

Is there continuity?

YES

Repair an open in the SG wire between the rear differential fluid pressure sensor and the AWD control unit.