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

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

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.

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 AWD WITH INTELLIGENT CONTROL with the HDS.
3. With the engine running, do the AIR BLEEDING in the ADJUSTMENT with the HDS.
4. Check for DTCs with the HDS.

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).

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).

Is there about 0.1 V or less?

YES

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.

NO

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

5. Rear differential pump motor internal shorted check 1:

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

Is there continuity?

YES

Replace the rear differential pump motor.

NO

Go to step 6.

6. Rear differential pump motor internal shorted check 2:

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

Is there about 0.6 Ω or less?

YES

Replace the rear differential pump motor.

NO

Go to step 7.

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

1. Disconnect the following connector.

AWD control unit 24P connector

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

Is there continuity?

YES

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

NO

Go to step 8.

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

Check for continuity between test points 1 and 2.

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

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.

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