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 DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 62 (ELECTRICAL COMPONENT LOCATOR)BUZZERS, RELAYS & TIMERS
1999 GMC Forward Control 5.7 R, Automatic
Buzzers, Relays & Timers
1999 GMC Forward Control 5.7 R, AutomaticSECTION Buzzers, Relays & Timers
WARNING: This page is about a different car, the 2002 GMC Savana and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
BUZZERS, RELAYS & TIMERS LOCATION
| Component | Location |
|---|---|
| Access Panel Relay (Left Side Front) | On rear fuse block. |
| Access Panel Relay (Left Side Rear) | On rear fuse block. |
| Access Panel Relay (Right Side) | On rear fuse block. |
| A/C Compressor Clutch Relay | On left side of engine compartment, in underhood fuse block. |
| Amplifier Relay | In rear fuse block. |
| Daytime Running Lamp (DRL) Rear Park Lamp Relay | Behind center of dash, in I/P relay block. |
| Door Lock Relay | Behind right center of dash. |
| Foglamp Enable Relay (Front) | Between foglight switch & multifunction alarm module, taped to harness. |
| Foglamp Relay (Front) | In rear fuse block. |
| Foglamp Relay (Rear) | Behind center of dash, in I/P relay block. |
| Fuel Pump (FP) Relay | On left side of engine compartment, in underhood fuse block. |
| Glow Plug Relay (6.5L VIN F) | On top right side of engine. See Figure . |
| High Speed Blower Motor Relay (Auxiliary) | Left rear of interior cabin, behind rear wheelwell. See Figure . |
| Horn Relay | On left side of engine compartment, in underhood fuse block. |
| Lighting Control Relay | Behind right side of dash. |
| Low Speed Blower Motor Relay (Auxiliary) | Left rear of interior cabin, behind rear wheelwell. See Figure . |
| Medium Speed Blower Motor Relay (Auxiliary) | Left rear of interior cabin, behind rear wheelwell. See Figure . |
| Power Brake (P/B) Booster Fluid Flow Alarm | Under left side of dash. |
| Rear Window Defogger Relay | On bottom of left "B" pillar. |
| Secondary Air Injection Reaction (AIR) Pump Relay | On left side of engine compartment, in underhood fuse block. |
| Starter Relay | On left side of engine compartment, in underhood fuse block. |
| Turn Signal/Hazard Flasher Module | Behind center of dash, in I/P relay block. |
| Upfitter Provision Relay | Behind left "B" pillar trim. |
RENDER: 1.0x
NO RELATED
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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.