* Under the hood, in the fuse box: This is the most common location. The fuse box itself might be located near the battery or on the firewall. Look for a diagram on the inside of the fuse box cover to identify the relay. The relay may be labeled, or you might have to consult a wiring diagram for your specific vehicle to identify it.
* Under the dash: Less common, but possible. Check near the fuse panel under the dash.
* In the under-hood relay center: Some S10 Blazers had a separate relay center under the hood. This is less common but worth checking.
To find it, you'll need:
1. Your owner's manual: This is the best place to start. It should have a diagram of the fuse box and relay locations.
2. A wiring diagram: If your owner's manual doesn't help, a wiring diagram specific to your 1985 S10 Blazer (including engine size and options) will be crucial. You can often find these online through forums dedicated to classic GM trucks or through online parts suppliers.
3. A multimeter (optional but helpful): You can use a multimeter to test for power at the relay to confirm you've found the correct one.
Without a diagram, a visual inspection is your next best bet. Start by examining the fuse box under the hood. Carefully examine each relay, noting their size and any markings. The fuel pump relay is usually a standard automotive relay (a small square or rectangular box with several terminals).
Remember to be careful working around electrical components. Disconnect the negative battery terminal before starting any significant electrical work.
