Diagnostic Notes

NORMAL OPERATION
The antilock brake control module constantly monitors all the wheel speed signals to ensure that they are proper and do not drop out, have sudden spikes, or indicate a situation that is not physically possible.


FAULT DESCRIPTION
Codes are generated by the antilock brake control module's detection of a missing, erratic, or otherwise improper wheel speed signal from the right front brake antilock sensor. The codes are set for specific faults at various vehicle speeds that are as follows:

Code C1148: Antilock brake control module detects that the speed information from the right front brake antilock sensor has dropped out or is erratic for a significant period of time. This code is only set when the right front brake antilock sensor indicates speeds greater than 20 mph (brakes applied) or greater than 12 mph (brakes released).

1234: Antilock brake control module detects that the speed information from the right front brake antilock sensor is missing or very low (less than 8 mph) while the left front brake antilock sensor and vehicle speed sensor indicate a speed of greater than 12 mph. The antilock brake control module checks to make sure that drive train spin up is not occurring.

Code C1259: Antilock brake control module detects that the speed information from the right front brake antilock sensor does not match the left front brake antilock sensor and vehicle speed sensor usually indicating a missing or damaged right front brake antilock sensor indicator.

NOTE: More than one code may be stored for a given failure.

Codes C1148, C1234, and C1259 can NOT be set with the vehicle stationary. The vehicle should be driven when attempting to duplicate the concern. If Codes C1148, C1234, and C1259 are set, then the amber ABS warning lamp will come on and the ABS will be disabled. If the fault is corrected and the signal appears normal, the amber ABS warning lamp will be turned off and the ABS will be enabled. Codes are stored each time the amber ABS warning lamp turns on for any of the above reasons.






POSSIBLE CONTRIBUTING COMPONENTS/VEHICLE WIRING CONCERNS
- Damaged/missing right front brake antilock sensor indicator teeth or missing right front brake antilock sensor indicator
- Weak right front brake antilock sensor
- Air gap too small or too large
- Excessive axle vibration
- Loose right front brake antilock sensor in wheel end
- Intermittent short or open in Circuit 514 (Y/R) or 516 (Y/BK)
- Disturbances caused by ignition or Radio Frequency Interference (RFI)
- Defective trigger circuit in antilock brake control module