Diagnostic Routine B

Diagnostic Routine B

Diagnostic Overview

P187B

Refer to Wiring Diagram Set 34 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

The AWD (All-Wheel Drive) system uses input data from the ABS (Anti-Lock Brake System) module wheel speed sensors as inputs to the PCM (Powertrain Control Module). A dissimilar spare tire size (other than the spare tire provided) or major dissimilar tire sizes or incorrectly inflated tires between the front and rear axles could cause the AWD (All-Wheel Drive) system to stop functioning correctly.

DTC Fault Trigger Conditions






Visual Inspection and Diagnostic Pre-checks

- Matching wheel/tire size, brand and tread wear

- Tire pressure

Pinpoint Test

1. CHECK TIRE HISTORY

1. Check with customer about tire history or installation.

Has a tire been installed on the vehicle recently that was not originally supplied with the vehicle or has the mini spare been used?






2. CHECK TIRE SIZE, BRAND AND TREAD WEAR

1. Check the size, brand and tread wear of all 4 tires.

Are all 4 tires the same size, brand and tread wear?






3. CHECK TIRE AIR PRESSURES

1. Check the air pressure in all 4 tires.

Are all 4 tires at the recommended air pressure?






4. CHECK FOR CORRECT WHEEL SPEEDS

1. Using a scan tool, view ABS (Anti-Lock Brake System) PIDs (Parameter Identifications).

2. While driving the vehicle at 48 km/h (30 mph), monitor the ABS (Anti-Lock Brake System) module wheel speed sensor PIDs (Parameter Identifications):

- Left Front Wheel Speed Sensor (LF_WSPD)
- Left Rear Wheel Speed Sensor (LR_WSPD)
- Right Front Wheel Speed Sensor (RF_WSPD)
- Right Rear Wheel Speed Sensor (RR_WSPD)

Are all 4 wheel speeds within 2 km/h (1.2 mph) of each other?






5. CHECK FOR CORRECT PCM (Powertrain Control Module) OPERATION

1. Ignition OFF.

2. Disconnect and inspect all PCM (Powertrain Control Module) connectors.

3. Repair:

- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary

4. Reconnect the PCM (Powertrain Control Module) connectors. Make sure they seat and latch correctly.

5. Operate the system and determine if the concern is still present.

Is the concern still present?