Low Circuit Current

Control System DTCs

DTC Troubleshooting: C1851-18

DTC C1851-18 : Motor Circuit Low Current

NOTE: Before you troubleshoot, review the how to troubleshoot the real time AWD system.

1. Problem verification (with idling):

-1. Turn the ignition switch to ON (II).

-2. Clear the DTC with the HDS.

-3. Start the engine.

-4. Check for DTCs with the HDS.

Is DTC C1851-18 indicated?
-YES- The failure is duplicated. Go to step 3.
-NO- Go to step 2.

2. Problem verification (motor running):

-1. Clear the DTC with the HDS.

-2. With the engine running, do the Air Bleeding in the Adjustment Menu with the HDS Procedures.

-3. Check for DTCs with the HDS.

Is DTC C1851-18 indicated?
-YES- The failure is duplicated. Go to step 3.
-NO- Intermittent failure, the system is OK at this time.

3. Open wire check (GND line):

-1. Turn the ignition switch to LOCK (0).

-2. Disconnect the following connector.





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









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.









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.









Is there about 10 Ohms or less?
-YES- Update the real time AWD control unit if it does not have the latest software Real Time AWD Control Unit Update, or substitute a known-good real time AWD control unit Service and Repair, 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 Service and Repair.
-NO- Go to step 6.

6. Rear differential pump motor internal open check:

-1. Disconnect the following connector.





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









Is there about 10 Ohms 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- Replace the rear differential pump motor Rear Differential Pump Motor Removal And Installation (KA, KC Models AWD).

7. Rear differential pump motor internal shorted check:

-1. Disconnect the following connector.





-2. Check for continuity between the following test points and the rear differential pump motor body individually.














Are there continuity?
-YES- Replace the rear differential pump motor Rear Differential Pump Motor Removal And Installation (KA, KC Models AWD).
-NO- Repair a short in the MH and/or ML wires between the rear differential pump motor and the real time AWD control unit.