Diagnostic Aids
Virtually any abnormal electrical condition in main valve circuit could cause Code 21 to set. If a Code 21 condition is detected, anti-lock function will be disabled for remainder of ignition cycle and anti-lock light will be turned on. Conditions that can cause a Code 21 are:
- Shorted main valve solenoid.
- Open main valve solenoid.
- Short to ground on circuit No. 856.
- Short to voltage on circuit No. 856.
- Open in circuit No. 856.
- Open in circuit No. 150J.
- Open in circuit No. 150 between valve block and EBCM. Disconnecting the ABS valve block connector will set a Code 21.