That's top secret and I can't tell you! Translation: I don't know. At least not specifically for your car. Most commonly ground terminals are bolted to the inside of the "A" pillar, behind the kick panel on each side. On some cars you'll find them bolted to a metal brace that runs from left to right, between the two doors, under the dash. You might even find them bolted to the firewall, although that is less common.
Most manufacturers use multiple ground terminals for two, three, or four different circuits or wire harnesses, and bolt them all to the body with the same screw. Some others, Ford in particular, put all of their ground wires into a single terminal, then bolt that to the body. That way guarantees if there's a bad connection, one circuit will back-feed into the others and cause weird problems, but the symptoms will be consistent. The first way can allow one loose terminal to make its circuit dead without regard to interacting with the other circuits. What that means is you might have intermittent dash lights, intermittent interior lights, and an intermittent heater fan, but any one or all of them could stop and start working at any time. When just one common terminal is used for all the circuits, a bad connection will always cause the same circuits to act up at the same time.
That's just "nice to know" information but it doesn't help with the diagnosis. If you find a loose ground screw, first just try to tighten it. If it is stripped, you can stick a piece of solid copper wire in the hole first, then run the screw in. The wire will make the hole hold the screw better. You can also drill a new hole.
If any of the wires are corroded, you might be able to see it or you might be able to pull the wire out of the terminal. The outer insulation is crimped to the terminal too, but it will stretch like a rubber band if the wire is corroded apart inside that insulation. Cut the insulation back until you find clean and shiny copper, then crimp on a new terminal. I always solder them too for a foolproof connection. You can put multiple wires in one terminal, you can use a separate terminal for each wire, or any combination. All you're after is each wire is in a terminal that is bolted to the body.
Wednesday, October 15th, 2014 AT 9:35 PM