Thread: 99 Grand Prix - general (sorta) questions

Just bought a 99 Grand Prix (non super turbo - whatever).

Needs some work. It runs ok and is smogged. That’s half the battle here in Calif.

Some issues:

Heater core was bypassed - I assume that mean a replacement

Front windows do not work. - Is that a fuse? window regulator? Motor? How can i test? Is there any technical data regarding voltage readings I can test for at the switch to see if there is a short or help isolate the issue?

Power mirrors do not work - Switch? Fuse?

Fuel gauge is erratic - Sending unit at tank? Does that mean dropping the tank and replacing? Or is there something behind the dash I could check?

That’s' it for now. Any help or direction would be really appreciated.

I did buy a Chilton’s but as usual the information there is vague at best.

Thanks gang!

Heater core was bypassed - I assume that mean a replacement- time to pull the center console and airbox.

Front windows do not work. - Is that a fuse? window regulator? Motor? How can i test? Is there any technical data regarding voltage readings I can test for at the switch to see if there is a short or help isolate the issue?

Do you hear them try to work at all? Have you checked the fuses? Probabaly a bad window regulator as they are known to die on these cars quite often.

Power mirrors do not work - Switch? Fuse?- check fuses

Fuel gauge is erratic - Sending unit at tank? Does that mean dropping the tank and replacing? Or is there something behind the dash I could check? - Probably the sending unit in the tank. Known issue. Google it or search here.

That’s' it for now. Any help or direction would be really appreciated.

I did buy a Chilton’s but as usual the information there is vague at best. You sure its not a Haynes manual? My Chiltons has pretty good info???

Thanks for the tips Fordman. On the center console, is it just the center piece or do I have to remove the whole dash?

As for the windows, nothing. Totally dead. I haven't checked fuses yet. Just got this thing and haven't had a chance to really dig in yet

Shouldn't have to remove the whole dash. I just did mine in my 00 GT. Had to remove the entire center console section (where the shifter and cubby reside) Pull the cubby organizer out and you will see some nuts/screws there. There is also 2 near the ashtray up front. IIRC, the console top just snaps in place so be carefull pulling it up as to not break any clips.

Once the console is out, move both seats all the way back for room. Take a look under your dash dead center and you will see a the black air box (the part that directs air to the floor). Once you remove this the core is right there. There are a few bolts holding it in place inside the box that need to be removed, and of course don't forget to remove the heater hoses from under the hood.

I'm used to doing cores in Ford vehicles (where you do have to pull the entire dash) and had NEVER touched a GP core before and I got mine out, back in and running in about 2 hours, without the help of a Chiltons.

Search for heater core replacement here on the forums and I'm sure a guide will come up on how to get the heater box from around the core. If you can't find anything useful let me know as I may have a guide from when I was looking into it.

Ok, thanks FordMan. Good advice.

BillBoost - I will check fuses and such for the windows and misrros. there is a radio in teh thin that was just shoved un there. not connected. So who know what was done to the wiring on this car. The door panels were partially removed so someone was trygin to fix something.

this will keep me busy and out of my wifes hair for a while.

Update: I figured out the issue with the windows. The window motors were in a bag in the trunk. I pulled the door panel off and plugged in a motor. The switch worked one way but not the other. So the motor works. I pulled the switch apart and realized that GM used the same switch assembly as was on an old 97 Chevy Malibu I once had. I immediately knew the problem. The contacts under the switch actuator get very dirty. I cleaned them well and it worked perfectly.

Now I need to do the passenger side.

So, some progress.

[QUOTEThe window motors were in a bag in the trunk.][/QUOTE]

??? Lol, that's about the wierdest thing I've seen in a while. Why the hell would someone bother to pull the motors and not test things???

While you have the door panels off and access to the regulator slap some grease on it. Can't hurt to lube up what you can see. Will help them live longer once you get the windows working again.

Yeah, the guy I picked this car up from was short on the common sense scale. He had attempted to fix the fuel sender but neglected to put the seal back on correctly. Gas went everywhere when I topped off the tank. Shut down a gas station. Took me about an hour and some serious elbow grease but got it back on correctly. No leaks.