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P188D




Four Wheel Drive (4WD) Systems

Pinpoint Test D: DTCs P188C and P188D

Refer to Wiring Diagram Set 34, All Wheel Drive (AWD) for schematic and connector information Electrical Diagrams.

Normal Operation

The active, on-demand AWD (All-Wheel Drive) system uses data from other systems as inputs to the PCM. The PCM uses the inputs to determine the appropriate duty cycle to send to the AWD (All-Wheel Drive) relay module over hardwired command/control circuit and returns information over the feedback/monitor circuit.

- DTC P188C (AWD (All-Wheel Drive) Relay Module Communication Circuit)- When the PCM detects an open, a short to ground or voltage on the command circuit, this DTC is set and the AWD (All-Wheel Drive) relay module may not allow All-Wheel Drive (AWD) operation.

- DTC P188D (AWD (All-Wheel Drive) Relay Module Feedback Circuit)- When the PCM detects an open, a short to ground or voltage on the feedback circuit, this DTC is set and the AWD (All-Wheel Drive) relay module may not allow All-Wheel Drive (AWD) operation.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- AWD (All-Wheel Drive) Relay Module

- PCM

PINPOINT TEST D : DTCs P188C AND P188D

NOTE: Carry out a thorough inspection and verification as outlined before carrying out this pinpoint test. Refer to Inspection and Verification Four Wheel Drive (4WD) Systems.

D1 CHECK THE AWD (All-Wheel Drive) RELAY MODULE FOR VOLTAGE

- Ignition OFF.

- Disconnect: AWD (All-Wheel Drive) Relay Module C4379.

- Ignition ON.

- Measure the voltage between AWD (All-Wheel Drive) Relay Module C4379-1, circuit CBB70 (YE-BU), harness side and the AWD (All-Wheel Drive) Relay Module C4379-4, circuit GD151 (BK-GN), harness side.






Is the voltage greater than 10 volts?

Yes
GO to D3.

No
GO to D2.

D2 CHECK THE AWD (All-Wheel Drive) RELAY MODULE VOLTAGE SUPPLY CIRCUIT

- Measure the voltage between AWD (All-Wheel Drive) Relay Module C4379-1, circuit CBB70 (YE-BU), harness side and chassis ground.






Is the voltage greater than 10 volts?

Yes
REPAIR circuit GD151 (BK/GN) for an open. CLEAR the DTCs. REPEAT the self-test.

No
VERIFY BJB (Battery Junction Box) fuse 70 (10A) is OK. If fuse is OK, REPAIR circuit CBB70 (YE-BU) for an open. If BJB (Battery Junction Box) fuse is not OK, REFER to the Wiring Diagrams to identify possible causes of the circuit short Electrical Diagrams. CLEAR all CMDTCs (Continuous Memory Diagnostic Trouble Codes). REPEAT the self-test.

D3 CHECK THE AWD (All-Wheel Drive) RELAY MODULE CONTROL AND FEEDBACK CIRCUITS FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: PCMC175B.

- Ignition ON.

- Measure the voltage between AWD (All-Wheel Drive) Relay module C4379-3, circuit VCF35 (GN), harness side and chassis ground; and between AWD (All-Wheel Drive) Relay Module C4379-6, circuit VCF34 (WH), harness side and chassis ground.






Is any voltage present?

Yes
REPAIR the affected circuit(s) for a short to voltage. CLEAR the DTCs. REPEAT the self-test.

No
GO to D4.

D4 CHECK THE AWD (All-Wheel Drive) RELAY MODULE CONTROL AND FEEDBACK CIRCUITS FOR A SHORT TO GROUND

- Ignition OFF.

- Measure the resistance between AWD (All-Wheel Drive) Relay module C4379-3, circuit VCF35 (GN), harness side and chassis ground; and between AWD (All-Wheel Drive) Relay Module C4379-6, circuit VCF34 (WH), harness side and chassis ground.






Are the resistances greater than 10,000 ohms?

Yes
GO to D5.

No
REPAIR the affected circuit(s) for a short to ground. CLEAR the DTCs. REPEAT the self-test.

D5 CHECK THE AWD (All-Wheel Drive) RELAY MODULE CONTROL AND FEEDBACK CIRCUITS FOR AN OPEN

- Measure the resistance between AWD (All-Wheel Drive) Relay module, harness side and PCM, harness side as follows:

AWD Relay module Connector-Pin Circuit PCM Connector-Pin C4379-3 VCF35 (GN) C175B-54 C4379-6 VCF34 (WH) C175B-3






Are the resistances less than 5 ohms?

Yes
GO to D6.

No
REPAIR the affected circuit(s) for an open. CLEAR the DTCs. REPEAT the self-test.

D6 CHECK THE AWD (All-Wheel Drive) RELAY MODULE CONTROL AND FEEDBACK CIRCUITS A SHORT TOGETHER

- Measure the resistance between AWD (All-Wheel Drive) relay module, C4379-3, circuit VCF35 (GN), harness side and AWD (All-Wheel Drive) relay module C4379-6, circuit VCF34 (WH), harness side.






- Repeat this measurement while wiggling the harness.

Is the resistance greater than 10,000 ohms?

Yes
GO to D7
No
REPAIR the affected circuit(s) for a short together. CLEAR the DTCs. REPEAT the self-test.

D7 CHECK FOR CORRECT AWD (All-Wheel Drive) RELAY MODULE OPERATION

- Ignition OFF.

- Check PCM C175B and AWD (All-Wheel Drive) Relay Module C4379 harness and component side connectors for:
- corrosion.

- pushed-out/bent pins.


- Connect: AWD (All-Wheel Drive) relay module C4379.

- Connect: PCM C175B.

- Ignition ON.

- CLEAR the DTCs. REPEAT the self-test.

- Operate the system and verify if the concern is still present.

Is the concern still present?

Yes
INSTALL a new AWD (All-Wheel Drive) relay module. REFER to All Wheel Drive (AWD) Relay Module . CLEAR the DTCs. REPEAT the self-test.

If DTC P188C or P188D is retrieved again, INSTALL a new PCM.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

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