Electrical nightmare

Katstang

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Hi, I have a 98 gt very, my electrical is going nuts. So first the top has to be moved manually, the reading lights stopped working, the door lock buttons stopped working, now the unlock button turns on parking lights, lock button works IF I rev the engine, driver side window dosen't work, sometimes the speedometer stops working than comes back on but the o/d light starts flashing, and it's all starting to mess with the battery, and if the battery gets too low and I try to start it the alarm will go off. Also when I get around 55 the car seems to shift back and forth in and out of od annoyingly. And ideas of where to start looking?
 

ttocs

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we need to start simple and check your fuses. Don't bother with the manual just get on your back with a pair of plyers and pull/inspect every fuse in the box. It sounds like a PIA but trust me it takes less time than the manual and then we can be sure they are all good. After you are done there do the same thing for the box under the hood. Once we are sure they are good then you will need a volt meter or test light to check for power.
 
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Katstang

Katstang

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I check fuses all the time, but the one under the hood for the aux kept blowing if I put a certain phone charger I had in it. But hasn't blown for awhile and I got rid of that charger.
 

ttocs

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you check all the fuses, or the ones you think the manual says could be blown? I/we seriously need to know that they are ALL good in both boxes before we start testing for power or you will be chasing your tail. The power adaptor could be a bad adaptor or I have also found wire/metal inside the cig lighter that would short out when it was inserted correctly.
 
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Katstang

Katstang

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I have to use an online manual and I find it easier to just lay down and check them, and with all those things going crazy it just doesn't sum that up in a manual, but I was going to go check again under dash, checked under hood last night.
 

ttocs

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you have multiple problems going on. For example the flashing overdrive light means that a trouble code has been found and stored. I would check to see what that code is and it might explain a lot. The reading lights not working, you/we need to test for power at them as it could be as simple as the bulbs are burned out. For the unlock button messing with the parking lights I would see about disconnecting the factory keyless entry and see if that goes away.
 

Monday

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you have multiple problems going on.......
Pop the kick panel and pull the computer. Open it up and check if either of the two capacitors are leaking or look in any way "Touchy".

They are the only thing you can readily access, and if one or both are sketchy, the car will get screwed up; you can try and replace on your own - Me - or just buy a new computer.

If you opt to fix yourself, these things are double-sided soldered and you better be good at electronics. You can get the capacitors off ebay.

My car never ran better - I replaced both capacitors just cuz I was there - one was leaking, and that was all my electrics problems fixed in two days of working on this facawkta thing.

Good Luck :)
 

tvsn95

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Couple of thoughts
Basic, Check ALL grounds. under the hood and at the ECU. if the case of the ECU is not grounded well things don't work ( sometimes wont even run) The advice about the Capacitors is real sound advice, I have changed several over the years . These ECU's are old and they are old tech. They aren't hard to change and there are plenty of youtubes out there.
Also , check for proper charging system function, voltage swings cause CRAZY things that are hard to put your finger on, Steady 13.2 min volts 14.6 max . Hot and cold . they can act strange with temp changes. swings are normally regulator related, Having said that . the Parts house replacements are a real CRAP shoot too get a good one.
For all you guys,,,If you are chasing rich/lean changes . Idle issues from hot to cold. Go to the charging system and study it. ECU voltage is a global scaler for the injector offset.
Good luck
 

ttocs

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Couple of thoughts
Basic, Check ALL grounds. under the hood and at the ECU. if the case of the ECU is not grounded well things don't work ( sometimes wont even run) The advice about the Capacitors is real sound advice, I have changed several over the years . These ECU's are old and they are old tech. They aren't hard to change and there are plenty of youtubes out there.
Also , check for proper charging system function, voltage swings cause CRAZY things that are hard to put your finger on, Steady 13.2 min volts 14.6 max . Hot and cold . they can act strange with temp changes. swings are normally regulator related, Having said that . the Parts house replacements are a real CRAP shoot too get a good one.
For all you guys,,,If you are chasing rich/lean changes . Idle issues from hot to cold. Go to the charging system and study it. ECU voltage is a global scaler for the injector offset.
Good luck
this is all good advice. Checking grounds should always be the first part of any electrical diagnosis but to be sure to actually check them. We do not mean look at or even touch them a little as much as remove them, clean the connection with a wire brush/sand paper and then tighten them back down so they will not move.
 
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Katstang

Katstang

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you have multiple problems going on. For example the flashing overdrive light means that a trouble code has been found and stored. I would check to see what that code is and it might explain a lot. The reading lights not working, you/we need to test for power at them as it could be as simple as the bulbs are burned out. For the unlock button messing with the parking lights I would see about disconnecting the factory keyless entry and see if that goes away.
It did have a speed sensor code
 

ttocs

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that could be the problem with the overdrive light and it could be as simple as a bad sensor that is not too hard to fix. I thought it had specific codes for each wheel but I could be wrong.
 

Adfalenski

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It sounds like you have a loose connector somewhere. Loose connections can cause high current and/or intermittent operation. Is there a common connector or connectors to all these problems? Did you possibly disconnect the ECU and possibly not fully seated one of the connectors? As for the advice on the capacitors in the ECU, in the 1990s there were a lot of capacitors that were poorly made in China and are causing problems in electronic devices across the spectrum.
 
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Katstang

Katstang

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It sounds like you have a loose connector somewhere. Loose connections can cause high current and/or intermittent operation. Is there a common connector or connectors to all these problems? Did you possibly disconnect the ECU and possibly not fully seated one of the connectors? As for the advice on the capacitors in the ECU, in the 1990s there were a lot of capacitors that were poorly made in China and are causing problems in electronic devices across the spectrum.
No I haven't messed with the ecu, when I bought it the drivers window didn't work, nor did the cruse control or vert top, and the jerking in and out of od around 50-60 was happining, since than the interior lights and door locks stopped working, and sometimes the speedometer goes out. Just trying to find out myself if all those things are connected or groups of them anyway, fuses seem good except under hood one for the aux ports blows sometimes.
 

ttocs

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pull out the kick panels and check the mess of connectors in there. By check I mean look over closely and then pull/tug on the wires to see if any are loose and if the harnesses move at all when you pull on them. Don't be afraid to disconnect and then reconnect them all as that can help a bad connection as well. Most of the parts you are describing connect on either side of the dash in the kick panels and could be working loose.
 

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