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.
1999 GMC Forward Control 5.7 R, AutomaticFACTORY OEM SERVICE PROCEDURE
Circuit Protection Devices
CIRCUIT PROTECTION DEVICES
| Component | Component Location |
|---|---|
| Accessory Junction Block (School Bus) | Body builder installed. |
| Battery Junction Block (Commercial Van) | On left side of firewall, above relay bracket. See Figure. |
| Crank Fuse (Commercial Van) | On upper right side of steering column support. See Figure. |
| Crank Fuse (Motor Home) | In auxiliary fuse block, right of steering column. |
| Diode Network | On I/P harness (body builder installed). |
| I/P Fuse Block | Behind dash panel (body builder installed). |
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.