Have trouble with gauges. Q?

[Strut]

I have rebuilt my gauge cluster. New circuit grid on back. Had my amp meter converted to volts. Have my tach hooked up to hei dist. All new wiring and led bulbs... I'm having trouble with the temp gauge and fuel gauge. They are both factory units and work fine out of the truck. The temp gauge flips straight to hot when the key is turned on... Then the fuel gauge started at full and goes straight to empty. I took the cluster out and reset both gauges fuel to full and temp to cold. Turn the key on and they flip to opposite position.
My question: Is there a possibility that the cluster panel is getting grounded out and those gauges are malfunctioning?? I know these two gauges are on a ground loop....
Any help would be appreciated.
Thanks

[TBONE1964]

When you say "new wiring" what do you mean? Under dash harness complete? Did you purchase the harness from an aftermarket supplier? Is there any chance it is pinned wrong?

I would get a wiring schematic and make sure each and every wire is in the correct place on the connector. Also make sure that the sending unit has a good ground to it.

[JimKshortstep4x4]

Make sure the gauge housing has a good ground connected to it. The factory used a clip to ground the housing and there can be problems with the clip where it attaches to the dash.

Jim

[cdowns]

nothing electrical works without a good complete ground

[Strut]

Originally Posted by TBONE1964

When you say "new wiring" what do you mean? Under dash harness complete? Did you purchase the harness from an aftermarket supplier? Is there any chance it is pinned wrong?

I would get a wiring schematic and make sure each and every wire is in the correct place on the connector. Also make sure that the sending unit has a good ground to it.

I completely rewired the truck with American AutoWire harness. I have check all the wires and rechecked again.

[Strut]

Originally Posted by JimKshortstep4x4

Make sure the gauge housing has a good ground connected to it. The factory used a clip to ground the housing and there can be problems with the clip where it attaches to the dash.

Jim

I wasn't aware there was suppose to be a ground to the housing itself. Thought that was all done with the circuit panel... I'll try that. Thanks

[Strut]

Ok I grounded the gauge cluster, didn't solve the problem. I set the temp gauge to cold and put the fuel gauge on full, turned the key (without starting) and the temp flipped to hot and the fuel gauge to empty. I don't understand what the problem is...
Another thing, is the tach needle suppose to jump (move) when the key it turned on without running??

[powell72]

Did the truck always have gauges or did it originally have lights? If it always had gauges did these work fine before you did the refurb and wiring harnesses? Something is grounding out the temp gauge, and sounds like you may have a bad fuel sender, but we need more info.

[Strut]

Originally Posted by powell72

Did the truck always have gauges or did it originally have lights? If it always had gauges did these work fine before you did the refurb and wiring harnesses? Something is grounding out the temp gauge, and sounds like you may have a bad fuel sender, but we need more info.

It had gauges when I bought it. But the temp gauge wasn't hooked up... I realize that the sending unit might be bad, but it's a new fuel cell from summit. I find it odd that these two gauges are the only ones running off the circuit grid on the back of the cluster and they don't work. The volt meter is wired separately... Since it was converted from the amp meter.

[VetteVet]

Both your gauges are suffering symptoms of excessive grounding on the sending unit side.
Disconnect the ground wire at the temp sender and watch the gauge go to cold. if it doesn't change then the wire is grounded somewhere in the circuit. the key must be on of course. If it goes to cold then the sender is bad and has too low resistance.

Disconnect the fuel gauge wire either at the fuse panel location or at the fuel tank sender and the resistance to ground becomes very high so the gauge should go to full plus 1/4 or more. If you unplug it at the fuel tank sender and it doesn't change then try it at the fuse panel. if it changes to full plus, then the sender unit wire is grounded some where before the tank sender.

[Strut]

Ok. I called the company I got the wiring harness from and double she ked that everything was wired correctly. I have replaced the temp sending unit off the intake with a new one. Didn't change anything. Gauge still flips to hot when 12v is supplied. I have followed the wire from the intake to the cluster. It's not pinched or frade in any way. So I'm at a loss...
I did disconnect the rear wiring harness that has the fuel sending unit feed included. The gauge did flip passed full like mentioned above. So that's my next thing... Following the wire to the sending unit to check for it grounding out.

[VetteVet]

Originally Posted by Strut

Ok. I called the company I got the wiring harness from and double she ked that everything was wired correctly. I have replaced the temp sending unit off the intake with a new one. Didn't change anything. Gauge still flips to hot when 12v is supplied. I have followed the wire from the intake to the cluster. It's not pinched or frade in any way. So I'm at a loss...
I did disconnect the rear wiring harness that has the fuel sending unit feed included. The gauge did flip passed full like mentioned above. So that's my next thing... Following the wire to the sending unit to check for it grounding out.

Check your gauge resistors against this chart.


\
Here is a fuel gauge circuit for your viewing pleasure.



A view of the temperature gauge behind the cluster. Check the two terminals for continuity to ground. There are two small insulating sleeves one on each terminal to insulate them from the gauge cluster. If either of them are permitting the terminal to touch the gauge housing it will ground the gauge and produce the symptom you are experiencing. The positive side will blow a fuse of course.




same view

[Strut]

Originally Posted by VetteVet

Check your gauge resistors against this chart.

Attachment 1160988
\
Here is a fuel gauge circuit for your viewing pleasure.

Attachment 1160987

A view of the temperature gauge behind the cluster. Check the two terminals for continuity to ground. There are two small insulating sleeves one on each terminal to insulate them from the gauge cluster. If either of them are permitting the terminal to touch the gauge housing it will ground the gauge and produce the symptom you are experiencing. The positive side will blow a fuse of course.

Attachment 1160989


same view

Attachment 1160990

So I have determined that I have a bad fuel sending unit. I disconnected the wire from the sending unit and the fuel gauge moved to past full.
Now with the temp sensor I'm still lost.
I replaced the temp sending unit itself. No fix... Checked the wires again to splits. So I took another gauge out of a cluster I have laying around and wired it to the diagram above. Hooked 12v to the battery and touched the ground to the new sending unit on the motor (while it was cold) and the needle pegged to hott. But I did notice that in the diagram the resistor has a yellow square on the back. The one I have in the truck has a red square and the one on the test gauge I'm using has a orange square. Could this be the issue??
I appreciate the help...

[VetteVet]

Use an ohmmeter and measure the resistance of the resistor between the mount flange
and the terminal. look for 0 to 90 ohms as you move the float arm up and down.

[Strut]

Originally Posted by VetteVet

Use an ohmmeter and measure the resistance of the resistor between the mount flange
and the terminal. look for 0 to 90 ohms as you move the float arm up and down.

I was meaning the resistor on the temp sending unit.