Any Car Mechanics Electrical Demons

[1967vmax]

Ok im just about ready to torch my Daughters car i just bought her this year, shes 16 and the red Oldsmobile Achieva 3.1 aka Christine. Ok here is what it is doing car runs great,and this only happens when car is up to temp, you shut it off and it wont start,turns over but no power to the fuel pump. you have no dash lights, like check engine,airbag,seatbelt, you let the car sit for 45min to and 1hr bang turn key on lights come back on and Christine is good to go, So i took it to a good local mechanic he replaces the $175 ignition switch relay car runs great for a week and bang happens again take it back he trys a $235 ignition switch, car has anti theft so its the most expensive switch, so Christine runs great for 3wks thinking its fixed i drive it to put gas in it shut it off and notice the temp gage needle is not stoped on the cold its way below that so i turn the key and it goes up to temp, shut it off again and it returns to the cold normal position, so i pump my gas,get back in car , this is how Christine got her name,turn key to start and the freaking temp needle does a 360 and it wont starrt. no warning lights hell even the lights to the gear shift position were out noticed the temp gauge was not working as well as all dash warning lights. So i think computer because it only doing it when the car is hot my mechanic thinks i have a loose ground or a short somewhere, but my friend who also is a mechanic went over the car and check all the plugs and grounds and found nothing.Im suppose to take Christine back on tuesday to my mechanic. Anybody got any ideas HELP i have a torch ready to go. :bang head::ummm::angry flame::boxing00::2gunsfiring_v1::th_biggun:

 

[SpecOps13]

???? My Dodge has an alarm system from hell. It pretty much acts on it's own. I do know that there is a condition that can stop the entire vehicle from operation. Once it resets and no longer thinks it's being stolen it will start and run perfectly. Other than that your mechanic has covered the other things I'd have looked at.

Good Luck with Christine.

 

[Buster Hymen]

From my experience, when the display on the gauges goes all weird, it is a ground issue. The problem is trying to find the ground point that is affected. If you can get an electrical schematic for the car is a great help.

 

[1967vmax]

Ok but isnt it weird it only does it when its hot or up to temp?

 

[richwrench]

Bad PCM. More common on Chryslers, but I've had a few Chevys in my fleet with PCM issues. What model year is it ?

 

[1967vmax]

1997 3.1 auto. What is a PCM stand for?

 

[dmax1]

PCM = power control module

 

[richwrench]

If it was a passlock issue you should have a flashing security light on the dash when it won't start. Because you say you are losing lights, even the check engine light, that's more common with PCM failure. Are there any fault codes in the system ?

 

[1967vmax]

Yes there was but i dont know what they were, also this may be a seperate issue passanger side pwr window doesnt go up got another motor put it in an notice that its doing the same thing wonder if this could be related to my ground issue? or another bad motor?

 

[RaWarrior]

Does it use coil pack ignition? A lot of newer cars have a "pack" of four/six coils all next to each other somewhere in the engine spaghetti. They ground to the plate they're mounted on. Over time the surface between the coil pack and mounting plate gets nasty and you get starting problems. Remove all the individual coils and clean 'em up. That was the problem on a friend's car that had a "randomly won't start when hot" problem. Just sandpaper'd the mating surface and been fine since.

If that's not it, it does sound like a ground problem. Follow the negative cable(s) off the battery and see where they lead. Some cars have one cable that grounds to the engine block, often at a starter mounting bolt. I know Fords almost always have two, one engine ground, and one to the body(usually at the firewall near the battery).

When you say the gauge did a "360", do you mean it did a full sweep of it's range? A lot of cars "sweep" all the gauges after the battery has been disconnected, or power lost to the "memory" of the ECU.

Is the check engine light on when it does start? Does the car behave normally when it runs?

If the car was like Christine, it would be just the opposite, it would continually fix itself.

 

[1967vmax]

It does have the coil packs and i put another set on from the other motor . And yes it did a full 360 the temp gauge did a complete circle,and no check engine and before we put the other parts in the security light was on but now its not on the only weird light im getting now is the airbag it sometimes will stay on but you can turn the car off an start it back up again and it stays off. And i know Christine fixed herself but my daughter thinks this one has a mind of it own. LOL so she says its Christine

 

[RaWarrior]

That is a weird set of problems. Go to a junkyard and scrounge up a new ECU?

 

[06VMAXIMUS]

Sounds like the computer is not getting power/ ground. Usually the computer has to "see" the crank and cam position sensors before it will allow the fuel pump to start. If these sensors are not reading correctly when hot, all bets are off. Computers can be a PITA.

 

[mattness]

i second a ground issue also.

 

[1967vmax]

OK thanks for all the input.

 

[tugla]

when there are no lights on the dash and you hook up another car/jump it, do the lights come on?? will it start? also check ground off of the computer and connections to it, maybe loose/dirty?

edit:

buddy had a similar issue, not with the lights but no fuel pump power also, he was told that there is a security thing in the ignition, so turn the key on and leave it for 15-45 mins, then come back turn it off and start, and it worked. there is no chip key and the inside of the barrel needs to line up to let power to the pump, slightly different then your issue but might be worth a try.