Where is the power door lock relay on a 1999 GMC Suburban?

The power door lock relay location on a 1999 GMC Suburban isn't consistently located in one single place across all models and trim levels. It's often found within either the underhood fuse box or the interior fuse box (usually located under the dash, sometimes in the glovebox area).

To find it, you'll need to do the following:

1. Consult your owner's manual: This is the best place to start. The manual should have a diagram of your fuse box(es) showing the location of relays. Look for a relay labeled "power door locks," "power locks," or something similar. The diagram might even use a specific symbol for relays.

2. Check the underhood fuse box: This is usually a larger box located under the hood, often near the battery. Open it carefully and look for a diagram on the inside of the lid.

3. Check the interior fuse box: This is typically located under the dashboard, sometimes in the glove compartment. Again, look for a diagram on the inside of the lid.

4. If you can't find it using the diagrams: Some relays are not labeled clearly. You may need to use a multimeter to test each relay to determine which one controls the power door locks. You'll need to know which wire goes to the power door lock actuator to do this safely. Caution: Working with automotive electrical systems can be dangerous. If you're not comfortable with this, take your vehicle to a qualified mechanic.

Important Note: The relay might not even be a separate component. On some models, the power door lock function might be integrated into a larger body control module (BCM) or similar computer. Again, your owner's manual is your best resource. If you cannot locate the relay, this is a possibility.