DTC C1851-19 (63-02), C1851-1E (63-03), C1851-1E (63-04) (AWD)

DTC C1851-19  : Control Module Internal Control Module Malfunction DTC C1851-1E  : Motor Circuit High Current

NOTE:  Before you troubleshoot, review the General Troubleshooting Information .

DTC (Real Time AWD)

1. Problem verification (with engine idling)

   -1. Turn the vehicle to the ON mode.

   -2. Clear the DTC with the HDS.

   -3. Turn the vehicle to the OFF (LOCK) mode.

   -4. Start the engine.

   -5. Check for DTCs with the HDS.

   DTC Description	DTC	Freeze Frame
   C1851-19 Control Module Internal Control Module Malfunction
   C1851-1E Motor Circuit High Current

   Is DTC C1851-19 or C1851-1E indicated?

   YES 

   The failure is duplicated. Go to step 3.

   NO 

   Go to step 2.

2. Problem verification (with rear differential pump motor running)

   -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 ADJUSTMENT in the REAL TIME AWD with the HDS.

   -5. With the engine running, do the AIR BLEEDING in the ADJUSTMENT with the HDS .

   Air Bleeding

   Check for DTCs with the HDS.

   DTC Description	DTC	Freeze Frame
   C1851-19 Control Module Internal Control Module Malfunction

   DTC Description	DTC	Freeze Frame
   C1851-1E Motor Circuit High Current

   Is DTC C1851-19 or C1851-1E indicated?

   YES 

   The failure is duplicated. Go to step 3.

   NO 

   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.

3. Determine possible failure area (short to power in MH, ML lines, others)

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

   -2. Disconnect the following connector.

   Rear differential pump motor 2P connector

   -3. Turn the vehicle to the ON mode.

   -4. Wait for 10 seconds.

   -5. Measure the voltage between the following test points 1 and 2 individually (see table).

   Test condition	Vehicle ON mode
   	Rear differential pump motor 2P connector: disconnected

   Connector	Test point 1	Test point 2
   Rear differential pump motor 2P connector (female terminals)	No. 1:	Body ground
   	No. 2:

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

   Is there about 0.1 V or less?

   YES 

   Go to step 5.

   NO 

   Go to step 4.

4. Shorted wire check (MH line to power, ML line to power)

   -1. Disconnect the following connector.

   AWD control unit 24P connector

   -2. Turn the vehicle to the ON mode.

   -3. Measure the voltage between the following test points 1 and 2 individually (see table).

   Test condition	Vehicle ON mode
   	Rear differential pump motor 2P connector: disconnected
   	Real time AWD control unit 24P connector: disconnected

   Connector	Test point 1	Test point 2
   Rear differential pump motor 2P connector (female terminals)	No. 1:	Body ground
   	No. 2:

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

   Is there about 0.1 V or less?

   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 short to power in the MH and/or ML wires between the rear differential pump motor and the AWD control unit.

5. Determine possible failure area (short to ground in MH line, others)

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

   -2. Connect the following connector.

   Rear differential pump motor 2P connector

   -3. Disconnect the following connector.

   AWD control unit 24P connector

   -4. Check for continuity between the following test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	AWD control unit 24P connector: disconnected
   Test point 1	AWD control unit 24P connector No. 1
   Test point 2	Body ground

   Is there continuity?

   YES 

   Go to step 6.

   NO 

   Go to step 7.

6. Rear differential pump motor internal shorted check

   -1. Disconnect the following connector.

   Rear differential pump motor 2P connector

   -2. On the rear differential pump motor side, check for continuity between the test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Rear differential pump motor 2P connector: disconnected
   	AWD control unit 24P connector: disconnected
   Test point 1	Rear differential pump motor 2P connector (male terminals) No. 2:
   Test point 2	Body ground

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

   Is there continuity?

   YES 

   Replace the rear differential pump motor .

   NO 

   Repair short to ground in the MH wire between the rear differential pump motor and the AWD control unit.

7. Determine possible failure area (short in MH, ML line, others)

   -1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	AWD control unit 24P connector: disconnected
   Test point 1	AWD control unit 24P connector No. 1
   Test point 2	AWD control unit 24P connector No. 3

   Is there continuity?

   YES 

   Go to step 8.

   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 .

8. Shorted wire check (MH line to ML line)

   -1. Disconnect the following connector.

   Rear differential pump motor 2P connector

   -2. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Rear differential pump motor 2P connector: disconnected
   	AWD control unit 24P connector: disconnected
   Test point 1	Rear differential pump motor 2P connector (female terminals) No. 1:
   Test point 2	Rear differential pump motor 2P connector (female terminals) No. 2:

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

   Is there continuity?

   YES 

   Repair a short in the MH wire to the ML wire between the rear differential pump motor and the AWD control unit.

   NO 

   Replace the rear differential pump motor .