Unconcerned Posted September 17, 2009 Report Share Posted September 17, 2009 Been driving my 89 Grand prix for a few months now and finally got some motivation to fix a few of the problems im having with it. Only paid 250 bucks for it so no biggy as far as needing work and i've got a factory service manual on the way but if anyone can help me out with a few problems til I get that it'd be great! Firstly, when I turn on my heater it defaults to defrost. Cold/hot works fine but no matter what I select its always on defrost. I took a venture behind the glovebox and found some form of vacume modual and I tinkered with it and found it seems to be doing nothin. The electrical plug going to the modual doesnt seem to have any power going to it (Tested with test light) Could it be the selector on the dash? Second, the door locks and interior lights dont work. These quit about 2 weeks ago. Tried changing the fuse but it just burns the fuse reseting my radio and tripodometer. The door locks didnt work very good from the start requiring a few push's of the button to get them locked. They do seem to still try to lock automatically thou it accomplish's little since the actuators seem weak. None of the interior lights work from the door lights to the passenger mirror and I dont think the trunk or hood light are working either. Third, the oil pressure and coolant idiot lights are on, but the levels are good and according to the dash the temp and pressure are both fine. They have always been on thou on one occasion they did go out with the temp light kind of dimly glowing on and off. Havent tried changing either sensor but searching revealed that seems to fix that sort of problem, just kinda odd that they are both on. Otherwise the cars pritty decent for 250, has other niggling problems like the power anntenna being broken, the headliner dipping in the back corners (leak maybe?) the drivers door making an annoying sound when it opens and the sound of rubbing at full lock of the steering (And the damn turn signal switch feeling half broken and not staying selected for right turns/needing fiddling for it to work on left turns. Also seems to eat a little bit of coolant and theres a leak from a plug under the intake but compared to my old truck its a smooth ride and gets infinitly superior gas mileage. Thanks in advance for any replys. Jeff Quote Link to comment Share on other sites More sharing options...
Addicted To Boost Posted September 17, 2009 Report Share Posted September 17, 2009 Firstly, when I turn on my heater it defaults to defrost. Cold/hot works fine but no matter what I select its always on defrost. I took a venture behind the glovebox and found some form of vacume modual and I tinkered with it and found it seems to be doing nothin. The electrical plug going to the modual doesnt seem to have any power going to it (Tested with test light) Could it be the selector on the dash? You have a vacuum leak somewhere. Most likely cause is a bad/broken 3-way check valve under the hood right by your cruise control. They are common to go bad. Also be sure the vacuum lines are connected to the vacuum ball in front of the driver's front wheel on the underside of the car. Other than that, check all vacuum lines for damage, once you have proper vacuum, your cruise and your vents will work. As for the idiot lights, the sending units are also common to go bad, replace the coolant level sensor and oil pressure sender. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted September 17, 2009 Report Share Posted September 17, 2009 You have a vacuum leak somewhere. Most likely cause is a bad/broken 3-way check valve under the hood right by your cruise control. They are common to go bad. Also be sure the vacuum lines are connected to the vacuum ball in front of the driver's front wheel on the underside of the car. Other than that, check all vacuum lines for damage, once you have proper vacuum, your cruise and your vents will work. As for the idiot lights, the sending units are also common to go bad, replace the coolant level sensor and oil pressure sender. you are correct on the vacuum issue, but... the gauges working but the warning indicators stuck on is a good sign of bad solder joints on the cluster, very common with early GP clusters. read: http://www.w-body.com/service/checkgauges.html Quote Link to comment Share on other sites More sharing options...
Addicted To Boost Posted September 17, 2009 Report Share Posted September 17, 2009 Its only common on the 90-93 analog GP clusters. The 88-89 GPs had digital clusters and didn't have this issue. The coolant sensor IS a commonly failed part. Quote Link to comment Share on other sites More sharing options...
jeremy Posted September 17, 2009 Report Share Posted September 17, 2009 Its only common on the 90-93 analog GP clusters. The 88-89 GPs had digital clusters and didn't have this issue. The coolant sensor IS a commonly failed part. Fwiw my 89 gp had this same issue with both idiot lights on at the same time. It was the cluster Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted September 17, 2009 Report Share Posted September 17, 2009 On the lock/light issue, check the bundle of wiring that sits in front of the driver's door under the carpet. I found mine had migrated toward the center of the car, which meant the wires were being mashed every time I put my left foot down on the floor...found two wires in my bundle that had abraded to a point that they were shorting out against the floor. Since you report blown fuses, it sounds like a short, and this would be a good place to look. Quote Link to comment Share on other sites More sharing options...
Unconcerned Posted September 17, 2009 Author Report Share Posted September 17, 2009 Wow! Thanks for all the reply's! I forgot to mention that my cruise control also does not work but this vacume line check valve sounds like my quick fix ticket As far as the gauges go I also forgot that the oil pressure gauge tends to flutter and bounce to the max and where it should sit when at higher rpm's. Doesnt always do it. Are the gauges supposed to act like "Real" gauges? The oil pressure seems to display what im actually sitting at pressure wise, not just at normal unless all oil pressure fails and when my signal lights are on I can watch the voltage needle move when it clicks on and off. Im used to those useless gauges that just sit at normal til complete failure Anyway, back to work! I'll see if your suggestions fix my problems when im off. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted September 17, 2009 Report Share Posted September 17, 2009 functional? yes. accurate? no. Quote Link to comment Share on other sites More sharing options...
Unconcerned Posted September 18, 2009 Author Report Share Posted September 18, 2009 Well, I checked for vacuum at the cruise control actuator and found vacuum both from the engine and from the ball in the fender, then, like the moron I am, I decided to take the hose off the ball just to double make sure there was vacuum there. Broke the tit off the ball and now I need a new one. XP Then just to triple make sure I pulled the vacuum lines off at the control module just before the actuators and there was vacuum there too so im thinkin either there isent enough vacuum or the module isent letting vacuum to the actuators. Anyone know how much vacuum I should have? I think I got a random vacuum gauge kickin around in the garage somewhere Then I checked for the harness in front of the drivers door, but I didnt really remember the post by the time I looked for the bundle of wires so I pulled up a bunch of the carpet looking for a random bundle of wires before rereading it and realizing the wires were still neatly tucked by the doorjamb where they belong. I did find one lone wire coming off the harness in a small tube sorta like heat shrink and it didnt go anywhere. Soooo back to square one XP Quote Link to comment Share on other sites More sharing options...
89GP_SE Posted September 21, 2009 Report Share Posted September 21, 2009 Its only common on the 90-93 analog GP clusters. The 88-89 GPs had digital clusters and didn't have this issue. I had an 89 with idiot lights with the same problem, it too was also the cluster. Quote Link to comment Share on other sites More sharing options...
Addicted To Boost Posted September 21, 2009 Report Share Posted September 21, 2009 Strange.. I had an 89 with 224k on it with no issues Quote Link to comment Share on other sites More sharing options...
Twenty Posted September 21, 2009 Report Share Posted September 21, 2009 My cluster's idiot lights had been bad for a few years. I think it eventually got to the point where every light would malfunction. I had the cluster rebuilt and that solved the problem instantly. Quote Link to comment Share on other sites More sharing options...
Unconcerned Posted October 4, 2009 Author Report Share Posted October 4, 2009 Update! So I got my service manual in the mail the other day, first one i've bought for a vehicle i've owned....Is it ever huge! Checked out the electrical system for my hvac problem and realized from the schematics that I was looking at the electrical system backwards. Figured the buttons sent power to the actuators but I guess its the other way around, the buttons provide ground for the actuators power But when I checked for power at the selenoid bank there was none there either...checked fuses and they were all good but one was missing. Plugged a fuse in and tadaa! Who woulda thunk it. Only real issue I see now is that when I start my car all the dash lights, headlights tail lights, all of em, come on as long as the car is on. Maybe previous owner didnt like daytime running lights? Or are they supposed to be on? Then while I was at it I threw a fuse in the interior light slot for the hell of it...didnt burn it! But once I tried driving out of the garage it popped. Replaced again and tried to fiddle with things I had just touched to see if I could get it to burn again, stomped on the floor, plugged in my seatbelt shook the car nothing! So I left it and drove it yesterday and today. Finally burnt today on my way home (As I was demonstrating the workingness of my interior lights....they didnt work to prove me wrong) So there is still an issue there. Does the auto door lock circuit work from the same circuit as the door locks/interior lights? Guess I should check n see if there's change in my cigarrette lighter port as well O.o Then I checked for other issues. My left rear wheel has a bit of a rattle but I jacked it up and checked the bearing play and I cant find anything loose so unless the caliper or brake pads are rattling then im not sure where its coming from (The park brake levers are seized so they arnt rattling....but maybe the cables are....hmmm) But now I have heat! Out my vents even! <3 Edit: Ok, just checked and there was a penny in my cigarette lighter. Penny removed and replaced by Ipod charger to prevent problem. On the flipside, I noted that the autolocks seem to work even when the manual ones dont but I think many of you already knew that Now to just fix the oil leak, get rid of the rattles and add cupholders! Quote Link to comment Share on other sites More sharing options...
Night Fury Posted October 4, 2009 Report Share Posted October 4, 2009 Edit: Ok, just checked and there was a penny in my cigarette lighter. Penny removed and replaced by Ipod charger to prevent problem. I was going to suggest that!! It's a surprisingly common problem Quote Link to comment Share on other sites More sharing options...
Unconcerned Posted October 4, 2009 Author Report Share Posted October 4, 2009 Yeah, I feel like a bit of a fool. If only I smoked, the ash tray would be full of non-conductive butt's and ash instead Quote Link to comment Share on other sites More sharing options...
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