Topic: fuel gauge go to infinity when key turned on

[medicman]

What would make the fuel gauge needle scream all the way over past the full mark when the key is turned on??

Thanks.

[ta78w72]

Either a bad wire (s) or a bad sender.  You've got to disconnect the sender wire in the trunk near the latch.  See if the gauge moves when that sender wire is disconnected and when it's grounded.  It should show all the way one way when it's disconnected and all the way to the other side when it's grounded.  If you get that action from the gauge, the sender is bad or it's not grounded.  If you don't get that condition, the gauge can be bad.  But make sure you've got voltage at the gauge.

[medicman]

I unplugged the wire in the trunk and when I cycled the key to run it went past full and when I grounded it, it did the same thing.

Getting really tired of the wiring issues I have in the dash harness, Thinking it might be a good idea to pull the whole darn thing out and walk through each wire!!  Since I have other issues, I am wondering if it is a ground issue. Just don't know where to start looking.

[ta78w72]

It's not a wiring issue.  You just proved it's a gauge issue.  Replace the gauge.

[medicman]

ok will try that after lunch. will let you know. Would a bad gauge cause other wiring issues???

[medicman]

Couldn't wait, had to change the gauge, I must of did the test wrong? this gauge goes over to past full also when the key is cycled to run position.

I unplugged the five wire harness in the trunk and grounded the fuel sending wire, does it matter where I test the wire from? My wire is solid with no connector under the trunk latch. Should I cut the wire and test it from there?

[JoshRiess]

I had the same issue sort of my would go to full and then a 1/4 tank past it was not the wires it was the sending unit float stuck in the up position, Had to drop the tank and push it back down.
                                                        JOSH

[medicman]

I am open to any advise, Right now seems the more I touch the more other things on the dash are screwing up!! Now  my tach gauge goes to max rpm, signal indicators on the dash are lit up when the parking lights are turned on, oil and water gauge also go crazy when the parking lights are turned on.

As long as I don't turn on the parking lights, the gauges except for the fuel work normally with the key cycled to the run position

I have changed the light switch and no difference.

Changed the fuel gauge and again no difference.

Someone got a match!! Really lost on this one.

Only things that are not affected by the parking lights are the fan, rear defogger, cigarette lighter, radio and trunk release.

[eroc022]

sounds like a bad dash ground.... under it by the e brake pedal, small ground make sure your bottom bolts are clean and tight....

[medicman]

will look at that and see what happens.

[medicman]

Ok so I checked the small black ground under the e-brake and I tightened the dash corner bolts. No change. Lets start in a different direction. What would cause the door pin lights not to work? They did work yesterday, thats when all hell broke loose. Maybe if I get that solved, It may solve my other issues.

There is no power to the door pin connectors. Where is the main + feed. All fuses are good.

Thanks

[brian c]

Your dome lights operate as follows:

Constant 12+ running to the lights.
Door jamb switches provide the ground to complete the circuit when the door is closed.


From the sounds of things you have multiple issues and need to focus on one issue at a time otherwise you're going to go nuts and not get anything accomplished...other than expanding your vocabulary

[medicman]

Thanks Brian, Going to check and see why there is not power at the light. I'm way past the going nuts part, my eyes have crossed and there is barely sigh of life in them, lol

Will keep you posted.

[ta78w72]

On the fuel gauge, if the volt gauge works it's not the ground.  They share the same ground.  Check for 12 volt at the pink wire of the fuel gauge connector.  Check the sender wire with an ohm meter, one end connected to the terminal in the trunk and the other at the terminal for the sender wire at the gauge connector.  It's possible that the sender wire has a break.

Or pull the gauge out and test it on your work bench.  You need a 500 ohm variable resistor and a 12 volt source.  Then follow the ohm readings in the service manual.

Electrical is easy to fix, but you need to understand how the circuits work.  Study.

[medicman]

Hollow heck, I traced the drivers side floor light, It's a little orange sucker, followed it across to roughly the middle of the car where the temp control is and it was broken in two?? I soldered it and heat shrinked the wire and the floor lights work now. But here is the kicker!! I plugged the gauge cluster back in and they are all working perfectly. no crazy signal lights or wild temp, oil and tach. Go figure. NO IDEA HOW THAT RELATES TO THE FLOOR LIGHT!!!!!!!!

Well it seems my eyes are starting to uncross, but not there yet.

ta78w72, the volt gauge works fine. there is +12 at the pink.

I will test the ohm in the trunk and let you know what happens.

Thanks guys, hate bothering you all, but I need all the help I can get.

Cheers