Pinpoint Test B: DTC P187B
Four Wheel Drive (4WD) Systems
Pinpoint Test B: DTC P187B
Refer to Wiring Diagram Set 34, All Wheel Drive (AWD) for schematic and connector information Electrical Diagrams.
Normal Operation
The All-Wheel Drive (AWD) system uses input data from the ABS module wheel speed sensors as inputs to the PCM. A dissimilar spare tire size (other than the spare tire provided) or major dissimilar tire sizes or improperly inflated tires between the front and rear axles could cause the AWD (All-Wheel Drive) system to stop functioning correctly.
- DTC P187B (Tire/Axle Out of Acceptable Range)- When the PCM detects an inappropriate size mini spare or road wheels/tires (greater than 7% difference in size across the front and rear axle or greater than 14% difference in size at one wheel on either the front or rear axle) installed, this DTC will be set.
This pinpoint test is intended to diagnose the following:
- Wheels/tires
- Wheel speed sensors
- ABS module
- PCM
PINPOINT TEST B : DTC P187B
WARNING: When directed to drive the vehicle as part of this test, drive the vehicle on a hard surface in an area without traffic to prevent a crash. Failure to follow these instructions may result in personal injury.
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.
B1 CHECK TIRE HISTORY
- 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?
Yes
INFORM the customer that tire size should not exceed OEM recommendations and that all 4 tires should be the same size and brand. CLEAR the DTCs. REPEAT the self-test.
No
GO to B2.
B2 CHECK TIRE SIZE AND BRAND
- Check the tire size and the brand of tire.
Are all 4 tires the same size and brand?
Yes
GO to B3.
No
INFORM the customer that tire size should not exceed OEM recommendations and that all 4 tires should be the same size and brand. INSTALL new tire(s) as necessary. CLEAR the DTCs. REPEAT the self-test.
B3 CHECK TIRE AIR PRESSURES
- Check the air pressure in all 4 tires.
Are all 4 tires at the recommended air pressure?
Yes
GO to B4.
No
ADJUST the tire air pressures. CLEAR the DTCs. REPEAT the self-test. INFORM the customer to maintain the correct tire air pressure.
B4 CHECK FOR CORRECT WHEEL SPEEDS
- Start the engine.
- Connect the scan tool.
- Enter the following diagnostic mode on the scan tool: DataLogger- ABS module.
- While driving the vehicle at 48 km/h (30 mph), monitor the following wheel speed sensor PIDs:
- 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?
Yes
GO to B5.
No
The ABS module is sending invalid wheel speed data to the PCM. REFER to Antilock Brakes / Traction Control Systems for additional ABS diagnosis.
B5 CHECK FOR CORRECT PCM OPERATION
- Ignition OFF.
- Disconnect: PCM C175B.
- Check for:
- corrosion.
- pushed-out pins.
- Connect the PCM and make sure it seats correctly.
- Ignition ON.
- CLEAR the DTCs. REPEAT the self-test.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes
INSTALL a new PCM. CLEAR the DTCs. REPEAT the self-test.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.