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2008 Grand Prix Cruise Control and Compass Not Working


Go to solution Solved by JSPitman,

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Howdy y'all!

I recently purchased a V8 2008 Grand Prix GXP, and after some minor aftermarket changes the cruise control and built in compass no longer work. And even weirder, it's not always broken. Sometimes they will work, but mostly not. Sometimes they'll work for awhile and then turn off mid drive. I don't know what the connection is between the two (compass and cruise control), but when the compass isn't displaying on the HUD, the cruise control doesn't work (at all, turn on or anything), while the inverse is also true.

I came here as I am completely at a loss as to what to do, and have tried reverting my changes to no avail.

Exactly what I did in order was first I installed a backup camera. The camera needed a 10a fuse thats tied to the ingition, so I shared the 10a Compass fuse slot since I figured the compass doesn't use a lot of power so surely there'd be no problem. After some issues fixing the grounding wire, it seemed to be working flawlessly. And seemed to work fine for several days (both the compass and backup camera).

Next, after said several days, I got the car tuned by DiabloSport using a T2. That's when the trouble started. On my way to an Autozone right after, the cruise control stopped working. It was working when I first started the car, but stopped about 5 minutes into the drive (just turned off and wouldn't turn back on). After that, it's been on and off. Sometimes working, sometimes not.

I tried reverting to stock programming, but that didn't fix it. Moreover, DiabloSport is certain it couldn't be their tune or tuner since the tune doesn't do anything to the cruise control or anything directly influencing it.

I also tried removing the camera's fuse from the 10a slot and put in the original fuse. That didn't work either.

My only thought is I fried something in the system or harness, or something somehow came loose. I got no clue where to even look beyond the fuse box. I even replaced the Cruise Control Switch's 2a Fuse and that didn't help either.

Any suggestions of what to do next would be extremely appreciated, as this is just not my field of expertise.

Thanks

Edited by JSPitman
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  • Founders

Best advice I can give is check the ground again and may need to check all the wiring/harness/etc. As you reverted all your changes, it sounds like something may have happened to the wiring in the process or with the throughput. 

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17 hours ago, JSPitman said:

Howdy y'all!

I recently purchased a V8 2008 Grand Prix GXP, and after some minor aftermarket changes the cruise control and built in compass no longer work. And even weirder, it's not always broken. Sometimes they will work, but mostly not. Sometimes they'll work for awhile and then turn off mid drive. I don't know what the connection is between the two (compass and cruise control), but when the compass isn't displaying on the HUD, the cruise control doesn't work (at all, turn on or anything), while the inverse is also true.

I came here as I am completely at a loss as to what to do, and have tried reverting my changes to no avail.

Exactly what I did in order was first I installed a backup camera. The camera needed a 10a fuse thats tied to the ingition, so I shared the 10a Compass fuse slot since I figured the compass doesn't use a lot of power so surely there'd be no problem. After some issues fixing the grounding wire, it seemed to be working flawlessly. And seemed to work fine for several days (both the compass and backup camera).

Next, after said several days, I got the car tuned by DiabloSport using a T2. That's when the trouble started. On my way to an Autozone right after, the cruise control stopped working. It was working when I first started the car, but stopped about 5 minutes into the drive (just turned off and wouldn't turn back on). After that, it's been on and off. Sometimes working, sometimes not.

I tried reverting to stock programming, but that didn't fix it. Moreover, DiabloSport is certain it couldn't be their tune or tuner since the tune doesn't do anything to the cruise control or anything directly influencing it.

I also tried removing the camera's fuse from the 10a slot and put in the original fuse. That didn't work either.

My only thought is I fried something in the system or harness, or something somehow came loose. I got no clue where to even look beyond the fuse box. I even replaced the Cruise Control Switch's 2a Fuse and that didn't help either.

Any suggestions of what to do next would be extremely appreciated, as this is just not my field of expertise.

Thanks

Two things come to mind. First, these cars like the “97”-“03” Grand Prix run a 12 volt multi wire ignition switch. This means they have several 12 volt supply wires that feed different components. The ignition switch internally has multiple finger & tabs that make contact to transfer power to these wires. This situation causes the fingers to burn/corrode when you leave components on & turn the car off, then return to restart the car, similar to the way points in a distributor do. During that start cycle it causes the finger to arc across to the tab that has been left on. When this burning gets bad enough they no longer transfer 12 volts. So the voltage can fluctuate & cause your problem. In many cases it will reduce the voltage output to millivolts. To check for this condition you need a volt meter. Go down the steering column to where the ignition wire harness connects to the distribution harness. With the key on, start checking at the back side of the plastic connector the wire clip you will be able to see through each wire slot.

The other possibility, though I doubt it is the body module.

Edited by Last Indian
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Hey, thanks both of you for your responses. But its turns out the issue was just me being dumb and not listening to my dad's advice from a day earlier.

He had suggested that the fuse's socket may have gotten bent/expanded, so the fuse wasn't making good contact. I brushed that asside as I was certain it was making contact, and thought I'd verified such using a voltmeter. Turns out, my tests were a fluke. He had a look at it hinself after I asked about y'alls suggestions, and he just bent the pin on the fuse a bit and jammed it in there, and now everything works perfect. (Both the compass and cruise control. Still not sure why one breaks the other, but doesn't matter now).

I guess while installing the camera fuse, I must've somehow buggered the socket up.

Eitherway, thanks again for trying to help, it means a lot to me even if in the end the solution was something else.

Moral learned, though- always trust a dad's intuition.

Edited by JSPitman
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