* Under the hood in the fuse box: This is the most common location. The fuse box is usually located either near the battery or on the fender wall. Open the fuse box cover and look for a diagram showing the relay locations. The relay itself might be labeled, or you might need to consult your owner's manual or a wiring diagram specific to your truck's year and engine.
* Under the dash: Less common but possible, especially if the underhood fuse box is smaller.
* In the cab, near the steering column: Again, less common.
To find it:
1. Consult your owner's manual: This is the best place to start. The manual should have a diagram showing the location of all fuses and relays.
2. Check the underhood fuse box: This is the most likely location. Look closely at each relay and compare it to the descriptions in your owner's manual or a wiring diagram. Some relays are physically larger than others. The fuel pump relay is often a standard size and might be near relays for other essential components.
3. Look for online resources: Search for "1987 GMC Sierra Classic fuel pump relay location" along with your engine size (e.g., "5.7L"). Forums and online repair manuals may have pictures or additional information.
Important Note: Before working on electrical components, always disconnect the negative (-) terminal of your battery to avoid electrical shock or short circuits.
