Pinpoint Test B : DTC P187B
- WARNING: 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.
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 Condition PCM P187B:00 Tire Size Out of Acceptable Range - AWD Disabled / Limited Function: No Sub Type Information When the PCM detects an inappropriate size wheels/tires (greater than 5% 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. Possible Sources
- Wiring, terminals or connectors
- Wheels/tires
- ABS system
Visual Inspection and Pre-checks
- Inspect for correct tire size and inflation.
- B1 CHECK FOR RECENT DIFFERENT SIZED TIRE USAGE
- Check with customer about recent tire changes or installation.
Was a tire recently installed on the vehicle that was not originally supplied with the vehicle or has the mini spare been used?
Yes The concern may have been caused by the previously mismatched tires. VERIFY the tires do not exceed Original Equipment Manufacturer (OEM) recommendations and all 4 tires are the same size. No GO to B2 - B2 CHECK TIRE SIZE AND BRAND
- Check the tire size and brand.
Are all 4 tires the same size and brand?
Yes GO to B3 No Tire size should not exceed Original Equipment Manufacturer (OEM) recommendations and all 4 tires should be the same size and brand. INSTALL new tire(s) as necessary. - 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 tire air pressures to specifications. - B4 CHECK ABS WHEEL SPEEDS
- Drive the vehicle at 30 mph (48 km/h), 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 1.2 mph (2 km/h) of each other?
Yes GO to B5 No The ABS module is sending invalid wheel speed data to the PCM, Refer to: Anti-Lock Brake System (ABS) and Stability Control . - Drive the vehicle at 30 mph (48 km/h), monitor the following wheel speed sensor PIDs:
- B5 CHECK FOR CORRECT ABS AND AWD (ALL-WHEEL DRIVE) SYSTEM OPERATION
- Ignition OFF.
- Disconnect all ABS, AWD relay module, and Active Torque Coupling (ATC) solenoid connectors.
- Check for the following:
- 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
- Reconnect all ABS, AWD relay module, and Active Torque Coupling (ATC) solenoid connectors. Make sure they seat and latch correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no TSBs address this concern, INSTALL a new ABS. Refer to: Anti-Lock Brake System (ABS) and Stability Control . No The system is operating correctly at this time. The concern may have been caused by module connections. Address the root cause of any connector or pin issues.