P188B

Four Wheel Drive (4WD) Systems

Pinpoint Test C: DTC P188B


Normal Operation

The All-Wheel Drive (AWD) relay module outputs a high current Pulse-Width Modulation (PWM) signal to the Active Torque Coupling (ATC) solenoid voltage supply circuit which increases as torque demand from the PCM increases.

- DTC P188B (All-Wheel Drive (AWD) Clutch Control Circuit)- When the AWD (All-Wheel Drive) relay module detects an open, a short to power or ground on the ATC (Active Torque Coupling) solenoid voltage supply and or return circuit, this DTC is set and the AWD (All-Wheel Drive) relay module shuts off current to the ATC (Active Torque Coupling) solenoid.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- ATC (Active Torque Coupling) solenoid (part of rear axle)

- AWD (All-Wheel Drive) relay module

PINPOINT TEST C : DTC P188B

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

C1 CHECK THE ATC (Active Torque Coupling) SOLENOID AND CONTROL CIRCUITS FOR AN OPEN WITH ATC (Active Torque Coupling) SOLENOID CONNECTED

- Ignition OFF.

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

- Measure the resistance between AWD (All-Wheel Drive) relay module, C4379-5, circuit CCF21 (VT/WH), harness side and AWD (All-Wheel Drive) relay module C4379-8, circuit RCF21 (WH/VT), harness side.





- Repeat this measurement while wiggling the harness.

Is the resistance less than 10 ohms?

Yes
GO to C3.

No
GO to C2.

C2 CHECK THE ATC (Active Torque Coupling) SOLENOID CONTROL CIRCUITS FOR AN OPEN

- Measure the resistance between AWD (All-Wheel Drive) relay module, harness side and ATC (Active Torque Coupling) solenoid, harness side as follows:

- AWD Relay module Connector-Pin Circuit ATC solenoid Connector-Pin C4379-5 CCF21 (VT/WH) C4347-1 C4379-8 RCF21 (WH/VT) C4347-2






Is the resistance less than 5 ohms?

Yes
INSTALL a new rear axle assembly. CLEAR the DTCs. REPEAT the self-test.

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

C3 CHECK THE ATC (Active Torque Coupling) SOLENOID CONTROL CIRCUITS FOR A SHORT TO POWER

- Disconnect: ATC (Active Torque Coupling) Solenoid C4347.

- Ignition ON.

- Measure the voltage between AWD (All-Wheel Drive) relay module C4379-5, circuit CCF21 (VT/WH), harness side and chassis ground; and between AWD (All-Wheel Drive) relay module C4379-8, circuit RCF21 (WH/VT), harness side and chassis ground.






- Repeat this measurement while wiggling the harness.

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 C4.

C4 CHECK THE ATC (Active Torque Coupling) SOLENOID CONTROL CIRCUITS FOR A SHORT TO GROUND

- Measure the resistance between AWD (All-Wheel Drive) relay module C4379-5, circuit CCF21 (VT/WH), harness side and chassis ground; and between AWD (All-Wheel Drive) relay module C4379-8, circuit RCF21 (WH/VT), harness side and chassis ground.






- Repeat this measurement while wiggling the harness.

Are the resistances greater than 10,000 ohms?

Yes
GO to C5
No
REPAIR the affected circuit(s) for a short to ground. CLEAR the DTCs. REPEAT the self-test.

C5 CHECK THE ATC (Active Torque Coupling) SOLENOID CONTROL CIRCUITS FOR A SHORT TOGETHER

- Measure the resistance between AWD (All-Wheel Drive) relay module, C4379-5, circuit CCF21 (VT/WH), harness side and AWD (All-Wheel Drive) relay module C4379-8, circuit RCF21 (WH/VT), harness side.






- Repeat this measurement while wiggling the harness.

Is the resistance greater than 10,000 ohms?

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

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