Where is location of glow plug relay in 1993 GMC Sierra 3500 6.5 l engine?

The glow plug relay location on a 1993 GMC Sierra 3500 with the 6.5L engine is under the hood, in the Power Distribution Center (PDC) or fuse box. It's not always easy to visually identify without a wiring diagram or the specific service manual for your truck. The relay itself will likely be a larger relay than most others in the PDC.

Unfortunately, I can't give you a more precise location without seeing the specific PDC layout for your truck. Your best bet is to:

1. Consult your owner's manual: This should have a diagram of the fuse box and identify the glow plug relay.

2. Look for a wiring diagram: A Chilton's or Haynes repair manual for your vehicle will provide a detailed diagram showing the relay's location and connections.

3. Use a multimeter: With the engine off, trace the wiring from the glow plugs back to the PDC. This will lead you to the relay. Be cautious when working with automotive electrical systems.

4. Search online forums: Search online forums specific to GMC Sierra 6.5L diesel trucks. Someone may have posted a picture or description of its location for your model year.

Remember to always disconnect the negative battery terminal before working with any electrical components in your vehicle.