thought i had it beat! oil gauge electric dilemma

[jgurnari]

have all the correct wiring in the rear tail light figured out EXCEPT what i believe to be the oil gauge wire.. thought Inhad it figured out when I had all wires in and the gauge did not pin up.. it was down Until i turned on the key… then it pinned again, if I move a gray double wires connecter into a different slot the gauge will pin up with key off with light switch pulled out… with that out the rear right license plate light doesn’t come on. that tells me the double grey wire is for the plate and the green is for the gauge .. i put test light on green and nothing no power. if i’m getting no power why will it pin up?

[jgurnari]

guess the question is, how, if possible, to diagnose
whether the oil sender or the gauge is broken.

[Nditiz1]

When you turn on the car the gauge should click or move to the top of the curved line - max oil. If you take one of the wires at the tank, can't remember if gray or brown, but you ground it, the needle should drop to the bottom - no oil. If that I all working your gauge is fine. Then pull the sender out hook the wires to it and operate the float. If it doesn't do anything either the contact part is not close enough and it needs fixing or it's broke and just replace. With that said, your best measurement is sticking your head in your engine bay and check the stick.

[jgurnari]

Thanks,Ill try that.

What do you think about having the green wire at the rr 6 pin tail light connector not getting power? I used a test light and nothing.

Could it be as easy as the sender gasket being bad?... seems a strange coincidence the gasket went bad the same time I changed the oil and took all the pins out and re-attached the tail light connector wires.

[Walt Fricke]

If the oil level gauge sensor line isn't connected to a resistance to ground, when you turn the key to run the gauge will peg. Same gauge internals as the oil pressure gauge.

So hunt around for a wire back there which, when grounded, will cause the gauge to show something other than being pegged. Then connect that to the sensor to its connection on the sensor (not to the grounded lug on the sensor, which might be sort of superfluous, but still should have a ground connection to it).

At a guess, there may be a disconnect somewhere between the gauge and the sensor. Check your wiring diagram to see where the connectors are. You can check the sensor with your ohmmeter - you should get a resistance from the signal lug to ground.

The sensor contains a sliding contact attached to a float (sort of like in a toilet) to move with the oil level. The contact slides along a resistance wire coil, varying the resistance. Like the oil pressure sensor, eventually the resistance wire can wear through.

[jgurnari]

Walt Fricke do you mean hunt around the back of the gauge? should I pull a wire from the gauge and ground it to see if the gauge moves down?

as of now the 2 wires are connected on the sender.. needle is at the bottom, but when i turn on the lights it pegs up.

[Nditiz1]

Sounds like a missing ground or wires are not connected correctly. Lights should in no way move gauge needles.

[Walt Fricke]

Not "a" wire. The sensor wire. With the key to run, grounding the sensor terminal on the gauge (you shouldn't even need to remove it, just ground the terminal) should show no oil on the gauge. Then removing the sensor wire from the gauge (no ground) should show an overfull condition, so to speak - peg it.

If that checks out, problems are not in the gauge.

This business of turning on lights says someone has wired things up wrong - perhaps one of the gauge lights is connected not to a bulb in the gauge but to perhaps the positive terminal of the oil level gauge? And there is an open somewhere in the gauge sensor circuit?

You do have a wiring diagram showing what wire colors are supposed to be what, don't you?

[jgurnari]

this all started when the rear tail light housing harness plug came out and all the wires came out of the inside/ female harness plug itself. I did figure out the sequence of wires to work the lights in the taillight housing.. reverse. brake, driving, blinkers. everything working, That is when the oil gauge got crazy.
i have one wire in that plug, green, that i believe is the level wire. iI do not get any power from that wire… not sure if it should.

I don’t think the issue is at the gauge unless im missing ground. (photo). i’m told the second ground there is sufficient.


unfortunately i am illiterate when it comes to reading electrical diagrams.. as much as i try.

thanks for your help

Originally Posted by Walt Fricke

Not "a" wire. The sensor wire. With the key to run, grounding the sensor terminal on the gauge (you shouldn't even need to remove it, just ground the terminal) should show no oil on the gauge. Then removing the sensor wire from the gauge (no ground) should show an overfull condition, so to speak - peg it.

If that checks out, problems are not in the gauge.

This business of turning on lights says someone has wired things up wrong - perhaps one of the gauge lights is connected not to a bulb in the gauge but to perhaps the positive terminal of the oil level gauge? And there is an open somewhere in the gauge sensor circuit?

You do have a wiring diagram showing what wire colors are supposed to be what, don't you?

[Nditiz1]

Are the wires at 9 oclock and 11oclock touching? It almost looks like they are. IF the problem came from when this was disturbed then the issue is with this connector. I do know that the wiring diagrams are not the greatest when stating which pin is correct.

[jgurnari]

when the photo was taken they may have been touching, have them in and out 10 times since ..but i straighten them out.. i did try each one individually so they were all good lights worked as they should.. except the green wire which shows no power with test light.

[Walt Fricke]

With the ignition in run, you should show 12V at the connector on the green/white wire.

The oil level gauge gets its ground through the level sensor.

If turning on the running/headlights lights the instrument lights, then it's case has its ground. I don't think the unused ground has anything to do with the problem.

[jgurnari]

Are you referring to the green / white wire at the rear plug or behind the gauge?

Im taking the sender, changing the cork gasket. out tomorrow and putting in a pigtail plug into the rear tail light housing. Maybe something will happen again for the best this time.

Originally Posted by Walt Fricke

With the ignition in run, you should show 12V at the connector on the green/white wire.

The oil level gauge gets its ground through the level sensor.

If turning on the running/headlights lights the instrument lights, then it's case has its ground. I don't think the unused ground has anything to do with the problem.

[911obgyn]

I think he is referring to the picture of the bulkhead fitting, black yellow and black green wires.