DTC C1851-18 (63-01): Motor Circuit Low Current

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
   C1851-18 Motor Circuit Low Current

   Is DTC C1851-18 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
   C1851-18: Motor Circuit Low Current

   Is DTC C1851-18 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. Open wire check (GND line)

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

   - 2. Disconnect the following connector.

   Real time AWD control unit 24P connector

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

   Test condition	Vehicle OFF (LOCK) mode
   	Real time AWD control unit 24P connector: disconnected
   Test point 1	Courtesy of HONDA, U.S.A., INC.

   Test point 2

   Body ground

   Is there continuity?

   YES 

   The GND wire is OK. Go to step 4.

   NO 

   Check for poor connections or loose terminals between the real time AWD control unit and ground (G603). If the connections are OK, repair an open in the GND wire between the real time AWD control unit and ground (G603).

4. Determine possible failure area (short in MH, ML lines, open in MH, ML lines)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Real time AWD control unit 24P connector: disconnected
   Test point 1	Courtesy of HONDA, U.S.A., INC.
   Test point 2	Body ground

   Is there continuity?

   YES 

   Go to step 7.

   NO 

   Go to step 5.

5. Determine possible failure area (MH, ML lines, real time AWD control unit)

   - 1. Measure the resistance between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode, At normal air temperature
   	Real time AWD control unit 24P connector: disconnected
   Test point 1	Courtesy of HONDA, U.S.A., INC.
   Test point 2	Courtesy of HONDA, U.S.A., INC.

   Is there about 10 Ω 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 

   Go to step 6.

6. Rear differential pump motor internal open check

   - 1. Disconnect the following connector.

   Rear differential pump motor 2P connector

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

   Test condition	Vehicle OFF (LOCK) mode
   	Real time AWD control unit 24P connector: disconnected
   	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 10 Ω or less?

   YES 

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

   NO 

   REAR DIFFERENTIAL PUMP MOTOR REMOVAL & INSTALLATION(AWD) .

7. 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 following test points 1 and 2 individually (see table).

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

   Connector	Test point 1	Test point 2
   Rear differential pump motor 2P connector	No. 1	Rear differential pump motor body
   	No. 2

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

   Are there continuity?

   YES 

   REAR DIFFERENTIAL PUMP MOTOR REMOVAL & INSTALLATION(AWD) .

   NO 

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