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.
1994 GMC Forward Control 7.4 NFACTORY OEM SERVICE PROCEDURE
PCV Valve
The wrong PCV valve may cause incorrect idle speed.
CODE 35 TERMINAL & CIRCUIT WIRING IDENTIFICATION
| Application | PCM Terminal | Wire Color | ||
|---|---|---|---|---|
| "C" & "K" Series | ||||
| 5.7L A/T | ||||
| IAC Coil "A" Hi | A3 | LT BLU/WHT | ||
| IAC Coil "A" Lo | A6 | LT BLU/BLK | ||
| IAC Coil "B" Hi | A8 | LT GRN/WHT | ||
| IAC Coil "B" Lo | A7 | LT GRN/BLK | ||
| "G" Series | ||||
| 5.7L A/T | ||||
| IAC Coil "A" Hi | A3 | LT BLU/WHT | ||
| IAC Coil "A" Lo | A6 | LT BLU/BLK | ||
| IAC Coil "B" Hi | A8 | LT GRN/WHT | ||
| IAC Coil "B" Lo | A7 | LT GRN/BLK | ||
| "P" Series | ||||
| 5.7L A/T | ||||
| IAC Coil "A" Hi | A3 | LT BLU/WHT | ||
| IAC Coil "A" Lo | A6 | LT BLU/BLK | ||
| IAC Coil "B" Hi | A8 | LT GRN/WHT | ||
| IAC Coil "B" Lo | A7 | LT GRN/BLK | ||
Factory Service Tools
Use the Manual With the Right Hardware
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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.