Pinpoint Test B : P187B: Notes
Diagnostic Overview
Diagnostics in this article assume a certain skill level and knowledge of Ford-specific diagnostic practices. Refer to Diagnostic Methods in Service Information for information about these practices. This pinpoint test is intended to diagnosis the wheels and tires, wheel speed sensors ABS module and PCM.
Refer to All Wheel Drive (AWD) , for schematic and connector information.
Normal Operation and Fault Conditions
The AWD system uses input data from the ABS module wheel speed sensor 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 system to stop functioning correctly.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| P187B | Tire Size Out of Acceptable Range - AWD Disabled | When the PCM detects an inappropriate size 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. |