1999 Grand Prix trunk release/reverse lights not working...

[glomgold]

I recently purchased a 1999 Grand Prix, which is a beautiful car sans one small problem. The trunk release, both in the glove box and on the key fob wont open the trunk. The only way I can get the trunk open is with the key. The larger part of the problem is that the back-up lights don't come on when the car is in reverse. I checked the manual and noticed that both the trunk release and back-up lights are controlled by the same fuse. The fuse that was plugged in looked fine, but I changed the fuse anyway hoping that would solve my problem, but it was a no go. Does anyone have an idea of what the problem may be? It seems like it should have an easy fix, but I don't know where to look.

Any help would be appreciated.

Thank you.

[BNaylor]

Welcome to AF.

That should be the back up lamp fuse (B/U LP). Although the fuse is good check for 12 volts at one side of the fuse socket. Ignition must be on.

[richtazz]

The trunk release will not work if the car is in gear, so check for a maladjusted shifter cable, or bad PRNDL (neutral safety) switch.

[glomgold]

Thanks for your help guys. I'd like to ask a couple more questions if you don't mind...

Originally Posted by BNaylor

Welcome to AF.

That should be the back up lamp fuse (B/U LP). Although the fuse is good check for 12 volts at one side of the fuse socket. Ignition must be on.

I had used a cheap light tester and got the light to come on when placed on one side of the fuse socket. Do you think I should retest with a miltimeter to make sure it's sending 12v? I had assumed if the fuse box is sending out voltage, it must be a wiring problem. However, the wiring could potentially be failing at any number of points, so I didn't exactly know where to start.

Originally Posted by richtazz

The trunk release will not work if the car is in gear, so check for a maladjusted shifter cable, or bad PRNDL (neutral safety) switch.

So you believe that if it's a wiring issue, it would most likely be malfunctioning wiring on the shifter? My brother and I had considered looking into that, but we didn't want to have to take apart the center console for nothing.

[tblake]

No, the PRNDL switch is actually located on the transmission. Or at least it was if things havnt changed. More than likely its misaligned. Can you start your car in neutral?

[john967]

Any luck with results? I have the same problem. I'm almost sure mine is a wiring problem due to a leaky battery The problem is determining which wire is fraid in the mix of 60 wires.

Let me know your progress please.

John

[BNaylor]

The wiring goes into the main fuse box and passes out before it reaches the applicable circuits and trunk release relay. I recall one member in the past had this similar problem in that area. Turned out to be a fried or bad wire.

The GM FSM wiring diagrams would probably help isolate the problem further.

[glomgold]

Originally Posted by BNaylor

The GM FSM wiring diagrams would probably help isolate the problem further.

Yeah, I was gonna check out a Haynes book from my library so I could view the wiring diagrams. I'm sure that would help a lot.

[BNaylor]

I don't believe the Haynes is a good reference to use. Best to use the GM Factory Service Manual (FSM) wiring diagrams applicable to your year Grand Prix.

[glomgold]

Originally Posted by BNaylor

I don't believe the Haynes is a good reference to use. Best to use the GM Factory Service Manual (FSM) wiring diagrams applicable to your year Grand Prix.

Do I buy one of those at a GM dealership?