Power comes & goes to trip computer/HVAC

[fmp3]

Just recently my 2002 GTP started to show a blank screen on my trip computer and at the same time my HVAC system is dead. After driving for a few minutes, both the trip computer and the HVAC system would kick in. Both would then continue working. One time when this happened my fan switch was on full so the air conditioner started up at full blast when it kicked on. When I turned the switch back to low, the whole system, including the trip computer, went out again. All other instruments as well as the radio continued to work. A few miles down the road, both of them kicked on again.

Can anyone tell me what the problem might be?

[fmp3]

Come on, guys, help me out. It is going to get reeeeeeeeeeeeal hot soon down here in south Louisiana and I don't have the slightest idea why my trip computer/hvac system is going off and on without warning. My car also suffers from the key-locked-in-ignition problem and I'm wondering if the two issues are connected.

Please help if possible.

[Afterburn]

I hear your pain.

My mothers 2000 Grand Prix has the same issue. The last time I drove it everything was fine, but two weeks ago the HVAC dash control unit did not work, no power. Just yesterday I noticed the trip computer screen was blank (off) as well. As I do not drive this car often I didn't even notice if the trip computer was working two weeks ago when the heater failed. So far this problem is not intermittent, but only have driven the car three times in the past two weeks.

[EJOUIE]

Definitely something electrical. not sure on how to fix though, need some who has opened the dash to chime in.

Or maybe you can pull the radio and see the wiring...

[Scottydoggs]

you never know , may be un hook the battery to reset the pcm may do the trick, electrical stuff aint my bag if ya know what i mean.

[FoSHO99]

http://www.grandprixforums.net/ignition_bypass.php

Most likely the fix to your problems...

[Afterburn]

Power was removed from the HVAC dash control unit as I removed it, opened it up to inspect for any burned componets. Nothing abnormal and reinstalled it. Will try the battery disconnection.

Please explain the ignition bypass. Is there something in the factory wiring/componets that is trashing these dash control units?

[FoSHO99]

Power was removed from the HVAC dash control unit as I removed it, opened it up to inspect for any burned componets. Nothing abnormal and reinstalled it. Will try the battery disconnection.

Please explain the ignition bypass. Is there something in the factory wiring/componets that is trashing these dash control units?

It bypasses a relay in the ignition that tends to die out slowly and is hard to get to, hence why they thought of making a bypass relay that is easier to replace. Flashing Dic/dic off sometimes and coming back on, other electrical issues in the car such as heated seats stop working, possibly blower motor resistor, that stuff is possibly related.

[Afterburn]

Well fmp3, we now share the exact problem. All power and full function returned to the trip computer or DIC...whatever its called and the AC/heater on my way to work this morning. As I know this news does not help you much right now, but I have some time this weekend to explore this issue a little more.

FoSHO99...I'm not sure I want to mess with making a bypass for the relay, however taking your advice on the relay causing this issue is worth my effort to replace.

Thank you everyone for your time and help.

[taman86]

so ignition switch then? mine does this also....

[Afterburn]

I'm not sure yet taman86, didn't do anything with it today as it was raining all day. But I did get some work done on the kitchen.

I'm hoping someone who has had this problem and found a solid fix chimes in before I buy any parts.

[jmt455]

I recently fixed these same issues on my '02 GTP.
My HVAC controls, DRL, DIC, HUD all were acting flaky.

The ignition switch had to be replaced.

I tried the bypass first, hoping to save the cost and effort of replacing the switch assembly, but the bypass only worked for a few start cycles. The ignition switch contacts were badly scorched/burned.

Use this diagnostic process to verify that it is the switch: Sparky's Answers: 2002 Pontiac Grand Prix Blower Inoperative, Erratic When I checked mine, I found 0 volts at the HVAC/DIC fuse.

Excellent write-up on switch replacement procedure here:Sparky's Answers: 2002 Pontiac Grand Prix, Changing The Ignition Switch

The best, bullet-proof solution would be to replace the switch AND install the bypass with the new switch. If you do this, the new switch will never see the high current loads and it should last indefinitely.

Switches are available from any auto supply. I actually got the best price on a Delco unit. Good luck!
Joe

[Afterburn]

I recently fixed these same issues on my '02 GTP.
My HVAC controls, DRL, DIC, HUD all were acting flaky.

The ignition switch had to be replaced.

I tried the bypass first, hoping to save the cost and effort of replacing the switch assembly, but the bypass only worked for a few start cycles. The ignition switch contacts were badly scorched/burned.

Use this diagnostic process to verify that it is the switch: Sparky's Answers: 2002 Pontiac Grand Prix Blower Inoperative, Erratic When I checked mine, I found 0 volts at the HVAC/DIC fuse.

Excellent write-up on switch replacement procedure here:Sparky's Answers: 2002 Pontiac Grand Prix, Changing The Ignition Switch

The best, bullet-proof solution would be to replace the switch AND install the bypass with the new switch. If you do this, the new switch will never see the high current loads and it should last indefinitely.

Switches are available from any auto supply. I actually got the best price on a Delco unit. Good luck!
Joe

Joe, your information is greatly appreciated sir. Awesome link to Sparky's as well, thank you. I wish I could buy you a beer.

Do you think over the years this switch assembly has been upgraded? I guess I'm hoping after 11 years they fixed it. That bypass mod looks complicated.

This car was my Mothers before she passed on. To my knowledge, this has never happened to her for the whole time she owned the car. (about 7 years)

Chuck

[jmt455]

Chuck,
Sorry for delayed reply...been traveling since Thursday.

I don't know if any changes have been made to the replacement switch design.

If you don't want to implement the bypass, you can still prolong the life of the replacement switch by turning off all your accessory loads (Blower motor and A/C off, radio off, seat heater and rear defroster off) before starting or shutting the car off. This minimizes arcing by limiting the current levels when the contacts open or close.

[fmp3]

Let me tell you what a strange feeling it was to search this forum for a problem I'm having and be directed to posts about the EXACT issue relating to my 2002 GP...strange because the original post was over two years ago...AND I WAS THE ONE WHO STARTED THE THREAD!!!!! Lo and behold, I have the same problem again and found my own post. Even stranger, I find that the only responses I've received to my posts have occurred WITHIN THE LAST MONTH...two years since I posted my original problem.

The ***** of it is...I can't remember how I solved the problem in 2009, but I think I had the ignition switch replaced. I went through a horrible rain and hail storm about a week ago and was thinking my blinking ECM and screwy HVAC workings were attributed to some moisture getting in somewhere it didn't belong. But after two-three days of everything working great, the whole shooting match shut down on me today...NO ECM and NO HVAC. And I'm just about to leave on a 400+ mile trip.

I have no idea what is going on and I can't believe I didn't remember starting this post in '09, but I will tell you that I looked in the owner's manual for the fuses related to the ECM (a 10amp on the top row in the inside fuse box) and, with wishful thinking my only incentive, I pulled it and sandpapered the semi-corroded connections until they were bright. After putting it back in, I cranked up the car and, of course, it works fine now. I figure it won't stop again until I'm about 200 miles in to my trip.

I'll keep monitoring this thread.

[fmp3]

Man...I AM getting old. I just remembered something about my original post.

Uh.....it wasn't the same 2002 Grand Prix. Different car. I've had two 2002 Grand Prix's back to back. My original post/problem was on my white, turbocharged bullet of a Grand Prix. My latest problem is on my mom's old, burgundy, naturally aspirated Grand Prix. It is still a sweet ride.

so....exact same problem, but two different 2002 Grand Prix's.

[taman86]

lol, thats kinda ironic. ive been having this problem since winter but i live in AZ and it gets cold but not bone shaking cold, so i delt with it. i too posted my problems with absolutely zero response to it. even a few other guys posted and they were asking the same questions to no avail. but those links have been bookmarked

[beau]

I want to express my utmost gradatude for the information provided here! It described the exact problem I have fought for 3.5 years with no help from the dealer or anyone in town though they did try. After reading tis I went out back and took the ignition switch from the spare GTP and installed it in the good car and INSTANT FIX! I went on to dissassemble the old switch and sure enough the contacts were fried. Thanks again and since I have full intentions of keeping this unit I have had since new on 11/26/06 I will keep posting anything odd I find to try and help someone. Thanks again, BEAU in Casper Wyo. email: beauparker@hotmail.com.

[jmt455]

Mods; please consider making this a sticky.
Thanks

[Afterburn]

It bypasses a relay in the ignition that tends to die out slowly and is hard to get to, hence why they thought of making a bypass relay that is easier to replace. Flashing Dic/dic off sometimes and coming back on, other electrical issues in the car such as heated seats stop working, possibly blower motor resistor, that stuff is possibly related.

I have replaced the ignition switch and still no power to both the DIC and HVAC control panel. Where is this factory relay located? I'll replace it, but this bypass looks to complicated.