Where does the rear trunk solenoid get its ground from? (Page 1/1)
Cliff Pennock MAR 14, 10:16 AM
So my rear trunk electronic release stopped working today. I measured +12V on the solenoid when I pressed the release button, and apparently it was not getting ground. As soon as I grounded the housing, the latch would work. Now I tested for ground at several points (bolts) in the lid and they were all grounded. But the bolts that hold the latch to the lid weren't grounded.

I removed the small black switch with the three wires and the middle wire had come loose. But that wasn't connected to ground. As a matter of fact, that entire switch is plastic so even it it was ground, it wouldn't ground the latch.



After I had removed the latch, I noticed a loose piece of metal in the hole that is normally covered by the latch. I have no idea what that is (couldn't see it very clearly).

So anyway, where does the latch normally get it's ground from?
fierosound MAR 14, 10:26 AM
The switch is for your trunk light/decklid ajar warning light and has it's own ground wire.

The decklid solenoid grounds through the latch onto hook on the rear trunk wall (so deck has to be closed).
When testing it while deck is open, I just run a jumper wire from the hook to the latch mechanism to ground it.

I have found a dead solenoid when testing a friend's car. New ones are hard to find.

NOTE: diagrams from 87 Service Manual (overkill, but others may need this info)








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[This message has been edited by fierosound (edited 03-14-2024).]

theogre MAR 14, 10:55 AM
Trunk solenoid rarely go bad.

Yes solenoid Ground is the part's body then thru the loop when closed.
Latch adjustment & other things w/ "power trunk" option is important because latch "problems" mean iffy or no solenoid ground.
Example: "dead" Truck Seal often mean nothing pushing up on the latch when close to keep good ground.
Many times some crap in the trunk get jammed in the latch doing same thing = "dead" solenoid.

But above switch wiring that has nothing to do w/ the solenoid has "rotted" may same problem in the solenoid.

More read the cave...

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Cliff Pennock MAR 14, 11:42 AM

quote
Originally posted by fierosound:

The decklid solenoid grounds through the latch onto hook on the rear trunk wall (so deck has to be closed).



Really??? I was testing it with the decklid open because it didn't work when the lid was closed. The hook is a bit rusted so maybe it didn't make proper contact. I'll clean it tomorrow and test again.

BTW, the solenoid works because it was working after I just run a wire from the latch to a ground somewhere.