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 MANUALSGMC1989MAGNAVAN 5.7 K, 3L80/M40REPAIR AND DIAGNOSIS (SINGLE PAGE)ELECTRICALCOMPONENT LOCATIONSELECTRICAL COMPONENT LOCATORBUZZERS, RELAYS & TIMERS
1989 GMC Magnavan 5.7 K, 3L80/M40
Buzzers, Relays & Timers
1989 GMC Magnavan 5.7 K, 3L80/M40SECTION Buzzers, Relays & Timers
BUZZERS, RELAYS & TIMERS LOCATION
| Component | Location | |
|---|---|---|
| A/C-Heater Blower Relay | On evaporator case, in engine compartment. | |
| Auxiliary Cooling Fan Relay | On right side of firewall. See Figure. | |
| Cold Advance Control Relay (Diesel) | On right side of firewall. | |
| Downshift Relay 3L80 (THM 400) | ||
| Component View | On right side of firewall. See Figure. | |
| 4.3L | On right side of firewall. See Figure. | |
| 5.0L & 5.7L - 1989 | On right side of firewall. See Figure. | |
| 5.0L & 5.7L - 1990 | On right side of firewall. See Figure. | |
| 7.4L - 1989 | On right side of firewall. See Figure. | |
| 7.4L - 1990 | On right side of firewall. See Figure. | |
| Fuel Pump Relay | ||
| Component View | On right side of firewall. See Figure. | |
| 4.3L | On right side of firewall. See Figure. | |
| 5.0L & 5.7L - 1989 | On right side of firewall. See Figure. | |
| 5.0L & 5.7L - 1990 | On right side of firewall. See Figure. | |
| 7.4L - 1989 | On right side of firewall. See Figure. | |
| 7.4L - 1990 | On right side of firewall. See Figure. | |
| Hazard Flasher Relay | Under left side of dash. | |
| Horn Relay | Behind left side of dash, on harness near fuse block. | |
| Power Door Lock Delay Relay | Behind left side of dash, above kick panel. | |
| Power Door Lock Relay | Behind left side of dash, above kick panel. | |
| Turn Signal Flasher Relay | On fuse block. | |
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.