Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1997 GMC Forward Control 5.7 R, AutomaticFACTORY OEM SERVICE PROCEDURE
Anti-Lock Brake System DTCS
ANTI-LOCK BRAKE SYSTEM DTCS
| DTC | Description |
|---|---|
| C0021 | RIGHT FRONT WHEEL SPEED SENSOR CIRCUIT OPEN OR SHORTED TO BATTERY VOLTAGE |
| C0022 | RIGHT FRONT WHEEL SPEED SENSOR SIGNAL MISSING |
| C0023 | RIGHT FRONT WHEEL SPEED SENSOR SIGNAL ERRATIC |
| C0025 | LEFT FRONT WHEEL SPEED SENSOR CIRCUIT OPEN OR SHORTED TO BATTERY VOLTAGE |
| C0026 | LEFT FRONT WHEEL SPEED SENSOR SIGNAL MISSING |
| C0027 | LEFT FRONT WHEEL SPEED SENSOR SIGNAL ERRATIC |
| C0029 | SIMULTANEOUS DROPOUT OF FRONT WHEEL SPEED SENSOR SIGNALS |
| C0035 | REAR SPEED SENSOR SIGNAL CIRCUIT OPEN OR GROUNDED |
| C0036 | REAR SPEED SENSOR SIGNAL MISSING |
| C0037 | REAR SPEED SENSOR SIGNAL ERRATIC |
| C0038 | WHEEL SPEED SIGNAL MALFUNCTION |
| C0041 | RIGHT FRONT ISOLATION SOLENOID CIRCUIT OPEN |
| C0042 | RIGHT FRONT DUMP SOLENOID CIRCUIT OPEN |
| C0043 | RIGHT FRONT ISOLATION SOLENOID CIRCUIT SHORTED |
| C0044 | RIGHT FRONT DUMP SOLENOID CIRCUIT SHORTED |
| C0045 | LEFT FRONT ISOLATION SOLENOID CIRCUIT OPEN |
| C0046 | LEFT FRONT DUMP SOLENOID CIRCUIT OPEN |
| C0047 | LEFT FRONT ISOLATION SOLENOID CIRCUIT SHORTED |
| C0048 | LEFT FRONT DUMP SOLENOID CIRCUIT SHORTED |
| C0051 | REAR ISOLATION SOLENOID CIRCUIT SHORTED |
| C0052 | REAR DUMP SOLENOID CIRCUIT OPEN |
| C0053 | REAR ISOLATION SOLENOID CIRCUIT SHORTED |
| C0054 | REAR DUMP SOLENOID CIRCUIT SHORTED |
| C0065 | PUMP MOTOR RELAY CIRCUIT OPEN |
| C0066 | PUMP MOTOR RELAY CIRCUIT SHORTED |
| C0067 | PUMP MOTOR CIRCUIT OPEN |
| C0068 | PUMP MOTOR LOCKED OR PUMP MOTOR CIRCUIT SHORTED |
| C0071 | EBCM INTERNAL FAULT |
| C0072 | EBCM INTERNAL FAULT |
| C0073 | EBCM INTERNAL FAULT |
| C0074 | EBCM INTERNAL FAULT |
| C0081 | STOPLIGHT SWITCH ALWAYS CLOSED OR SHORTED |
| C0086 | ANTI-LOCK INDICATOR LIGHT CIRCUIT SHORTED TO BATTERY VOLTAGE |
| C0088 | BRAKE WARNING LIGHT CIRCUIT SHORTED TO BATTERY VOLTAGE |
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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