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.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ELECTRICALCOMPONENT LOCATIONSELECTRICAL COMPONENT LOCATORCONTROL UNITS
1999 GMC Forward Control 5.7 R, Automatic
Control Units
1999 GMC Forward Control 5.7 R, AutomaticSECTION Control Units
CONTROL UNITS
| Component | Component Location |
|---|---|
| Accelerator Pedal Position (APP) Module (Commercial Van) | Attached to accelerator pedal. |
| Accelerator Pedal Position (APP) Module (Motor Home) | Attached to accelerator pedal. See Figure. |
| Cruise Control Module | On radiator support bracket. |
| Daytime Running Lamps (DRL) Module | Attached to I/P harness (body builder installed). |
| Electronic Brake Control Module (EBCM) | Below radiator, on lower crossmember. |
| Fuel Balance Pump Module (Dual Tanks Only) | On inside of left frame rail. |
| Fuel Pump Module | On top center of fuel tank. |
| Fuel Solenoid Driver (6.5L VIN F) | On side of fuel injection pump. See Figure. |
| Glow Plug Controller (6.5L VIN F) | On left rear of engine, near firewall. |
| Glow Plug Controller (6.5L VIN Y) | On left rear of engine, near firewall. |
| Ignition Control Module (ICM) (4.3L VIN W) | On right top of engine, at ignition coil. See Figure. |
| Ignition Control Module (ICM) (5.7L VIN R) | On right top of engine, at ignition coil. |
| Ignition Control Module (ICM) (7.4L VIN J) | On bracket at rear of intake plenum. See Figure. |
| Power Brake Booster Fluid Flow Indicator/Alarm Delay Module | Body builder installed. |
| Powertrain Control Module (PCM) (6.5L VIN F) | On left side of driver's island, on relay bracket. |
| Powertrain Control Module (PCM) (6.5L VIN Y) | On left side of driver's island, on relay bracket. |
| Seat Belt & Lamps Alarm Module | Attached to I/P fuse block. |
| Transmission Control Module (TCM) (6.5L VIN F) | On left side of driver's island, on relay bracket. |
| Transmission Control Module (TCM) (6.5L VIN Y) | On left side of driver's island, on relay bracket. |
| Vehicle Control Module (VCM) (Commercial Van) | On left side of radiator support. See Figure. |
| Vehicle Control Module (VCM) (Motor Home) | On top of radiator support. |
| Vehicle Speed Sensor (VSS) Calibrator (Motor Home) | On left side of driver's island, under relay bracket. See Figure. |
| Windshield Wiper Pulse Control Module | Tie strapped to engine wiring harness, under driver's island support. |
RENDER: 1.0x
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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.