DTC C1851-18

DTC C1851-18  : Motor Circuit Low 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. Enter the maintenance mode and start the engine .

   -5. 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. Turn the vehicle to the OFF (LOCK) mode.

   -3. Enter the maintenance mode and start the engine .

   -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
   C1851-18 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.

   AWD control unit 24P connector

   -3. Measure the resistance 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. 4
   Test point 2	Body ground

   Is there 1.0 Ω or less?

   YES 

   The GND wire is OK. Go to step 4.

   NO 

   Check for poor connections or loose terminals between the AWD control unit and ground (G503). If the connections are OK, repair an open in the GND wire between the AWD control unit and ground (G503).

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

   -1. Measure the resistance 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	Body ground

   Is there 1.0 Ω or less?

   YES 

   Go to step 7.

   NO 

   Go to step 5.

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

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

   Test condition	Vehicle OFF (LOCK) mode, At normal air temperature
   	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 about 10 Ω 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 

   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
   	AWD control unit 24P connector: disconnected
   	Rear differential pump motor 2P connector: disconnected
   Test point 1	Rear differential pump motor 2P connector (male terminals) No. 1:
   Test point 2	Rear differential pump motor 2P connector (male terminals) 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 AWD control unit.

   NO 

   Replace the rear differential pump motor .

7. Rear differential pump motor internal shorted check

   -1. Disconnect the following connector.

   Rear differential pump motor 2P connector

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

   Test condition	Vehicle OFF (LOCK) mode
   	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 (male terminals)	No. 1:	Rear differential pump motor body
   	No. 2:

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

   Are there 1.0 MΩ or more?

   YES 

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

   NO 

   Replace the rear differential pump motor .