DTC C1851-19 (63-02): Motor Circuit Low Current, C1851-1E (63-03), C1851-1E (63-04): Motor Circuit High Current(AWD)

NOTE:  Before you troubleshoot, HOW TO TROUBLESHOOT THE REAL TIME AWD SYSTEM (AWD) .

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. Start the engine.

   - 4. Check for DTCs with the HDS.

   DTC Description	DTC	Freeze Frame
   C1851-19: Motor Circuit Low Current
   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. Select the ADJUSTMENT in the REAL TIME AWD with the HDS.

   - 3. 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: Motor Circuit Low Current
   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	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.

   Real time 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	No. 1	Body ground
   	No. 2

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

   Is there about 0.1 V or less?

   YES 

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

   NO 

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

5. Rear differential pump motor internal shorted check 1

   - 1. On the rear differential pump motor side, measure the resistance between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Rear differential pump motor 2P connector: disconnected
   Test point 1	Rear differential pump motor 2P connector No. 2
   Test point 2	Rear differential pump motor body

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

   Is there continuity?

   YES 

   REAR DIFFERENTIAL PUMP MOTOR REMOVAL & INSTALLATION(AWD) .

   NO 

   Go to step 6.

6. Rear differential pump motor internal shorted check 2

   - 1. On the rear differential pump motor side, measure the resistance between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Rear differential pump motor 2P connector: disconnected
   Test point 1	Rear differential pump motor 2P connector No. 1
   Test point 2	Rear differential pump motor 2P connector No. 2

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

   Is there about 0.6 Ω or less?

   YES 

   REAR DIFFERENTIAL PUMP MOTOR REMOVAL & INSTALLATION(AWD) .

   NO 

   Go to step 7.

7. Shorted wire check (MH line to body ground)

   - 1. Disconnect the following connector.

   Real time AWD control unit 24P connector

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

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

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

   Is there continuity?

   YES 

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

   NO 

   Go to step 8.

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

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

   Test condition	Vehicle OFF (LOCK) mode
   	Rear differential pump motor 2P connector: disconnected
   	Real time AWD control unit 24P connector: disconnected

   Test point 1	Rear differential pump motor 2P connector No. 1
   Test point 2	Rear differential pump motor 2P connector 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 real time AWD control unit.

   NO 

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