Oil Level Gauge/Sender Diagnosis

[jkolesa]

recently my oil level gauge stopped working. i checked the connections on the sender and they seem ok. also, i had all of my gauges refinished by palo alto this past winter so i'm wondering if something they did failed.

so...... how do i test/diagnose the gauge and sender?

[jkolesa]

so when the wires are plugged into the sender or the hot lead is grounded the needle is at the bottom. if i unplug the leads from the sender the needle goes to the top.
so...... i replaced the sender and it behaves the same (dead needle). i hooked up the old sender to an ohm meter and the resistance varies as i move the float so it seems to be ok.
i dont know how the gauge works..... does it sound like a problem with the gauge?

[Neil '67 911S]

Run some wire from your oil level gauge into the tank wiring harness. Run a wire to ground into the engine compartment or somewhere you're sure is well grounded just in case the tank wiring ground wire is bad. Now see if the gauge works. If not, hook your ohm meter up to the wires that go into the gauge. I think these tests should isolate the problem OK.

Good luck!

[jkolesa]

Not really sure what you mean: I'll bypass the ground with a jumper but what will hooking the gauge up to an ohm meter prove? What should I see?

[Neil '67 911S]

LOL! We're getting mixed up between "oil level float gauge" and the "oil level dash gauge."

Remove the appropriate wires from the back of the dash gauge and attach your Fluke meter to the wires you removed. Keep the wires attached to the float level gauge. Since you know that the resistance changes OK when moving the float level arm and measuring at the float level gauge, you're now going to test to see if the dash gauge is seeing the same variation in resistance.

If it the resistance changes OK, then there's something wrong with the dash gauge. If the resistance doesn't vary when you move the float, then check the continuity of the wire between the float level gauge and the dash gauge.

I hope this is better!

[sithot]

Make this one a "sticky".

Tom

[blucille]

translation from English to American as follows:

verify that the resistance readings are (essentially) the same at the sender (at the oil tank) and at the wiring to the gauge in the dash to rule out any excessive resistance in the car's wiring.

If the readings are essentially the same, the gauge itself is likely at fault

[Neil '67 911S]

translation from English to American as follows:

What he said!

Bon chance!

[jkolesa]

ill try that. im just a little confused as how the gauge works since when the car is off or on or hot or cold the needle is at the bottom but jumps up to the top if the car is on and i disconnect the sender. if the sender is varying resistance to vary voltage to the gauge i would think it would happen opposite...?
so i pulled the gauge and am just as confused. im guessing the red wire (jumpers around) brings electricity so........ what would i hook the ohm meter to to check the signal from the sender? (the top of the gauge is at the bottom of the picture)

[blucille]

every picture tells a story, donut?

so, disregard the light bulbs. You can be sure the wire that jumps from the right side to the left is supplying power to the gauge (usually red), there also needs to be a ground (brown or black usually...black on yours, you see it is attached to the gauge housing) so the green wire is the sender, one for each gauge within this housing.

when the key is off, there is no power to the gauges, so it stays bottomed out, the green wire is bringing the signal from the sender, so this is where you want to attach your ohm meter.

good luck.