Oil pressure warning light

[njspider]

Light's not working. I'll check the bulb first but I'm never that lucky. Looking at the wiring diagram it seems this light has power to it with the key at on or run. When there's no oil pressure the sensor closes and provides the ground to light the bulb. Is this correct?? Also when looking under the dash, there's a relay mounted right near the fuse panel. The wires plugged into it are blue, red, black x 2, and yellow. The other end of the yellow wire is loose, not plugged into anything. What is it for and where would it go? (I hate electrical!) I'm getting too old to work under the dash of these little cars. Thanks for any help.

[spider2081]

I believe the relay is something not Fiat that has been added to your car.

To check your oil pressure light I would remove the wire from the sender and with the ignition in the "on" position touch the wire to ground and see if the light lights. If it does the sender is bad. If grounding the wire does not light the light then the bulb is most likely bad. the bulb is powered from Fuse 1 which has lots of other lights and gauges on it so if the oil pressure light is your only problem the fuse is most likely ok

[DaveMarcotte]

I believe the relay is something not Fiat that has been added to your car.

To check your oil pressure light I would remove the wire from the sender and with the ignition in the "on" position touch the wire to ground and see if the light lights. If it does the sender is bad. If grounding the wire does not light the light then the bulb is most likely bad. the bulb is powered from Fuse 1 which has lots of other lights and gauges on it so if the oil pressure light is your only problem the fuse is most likely ok

That's what I thought too but, with the wire not connect on my car (so not grounded) my light was on. Just installed a new sender and lights out with new sender and of course good pressure.

[spider2081]

That's what I thought too but, with the wire not connect on my car (so not grounded) my light was on. Just installed a new sender and lights out with new sender and of course good pressure.

I think your car has an oil pressure gauge and a low oil pressure warning light. Is this correct??

Are you saying the oil pressure gauge is working but the low oil pressure warning light does not come on when engine is not running??

[njspider]

My '82 has no gauge, just the light. I pulled the wire from the sender and grounded it and the light works. I cleaned the connection on the sender and reattached the wire. Turned the key to on position and light is on. Fired up the engine and light is off. Fixed, right? Not so fast. Kill motor and turn key back to on, no light! Check connection and it's tight. Pull wire and ground it and light is back on. My guess is that the sender is sticking in the open position. Ordered a new one (they're cheap) and hope it will solve the problem.

[DaveMarcotte]

That's what I thought too but, with the wire not connect on my car (so not grounded) my light was on. Just installed a new sender and lights out with new sender and of course good pressure.

I think your car has an oil pressure gauge and a low oil pressure warning light. Is this correct??

Are you saying the oil pressure gauge is working but the low oil pressure warning light does not come on when engine is not running??

No. I'm saying with the sensor not connected lite was on. My understanding was that you need pressure to ground the wire to turn the light off. So why would the light be on when wires not ground. Just curious as all working now. Cheers

[DaveMarcotte]

My '82 has no gauge, just the light. I pulled the wire from the sender and grounded it and the light works. I cleaned the connection on the sender and reattached the wire. Turned the key to on position and light is on. Fired up the engine and light is off. Fixed, right? Not so fast. Kill motor and turn key back to on, no light! Check connection and it's tight. Pull wire and ground it and light is back on. My guess is that the sender is sticking in the open position. Ordered a new one (they're cheap) and hope it will solve the problem.

I thing you're right.

[spider2081]

No. I'm saying with the sensor not connected lite was on. My understanding was that you need pressure to ground the wire to turn the light off. So why would the light be on when wires not ground. Just curious as all working now. Cheers

I rechecked the 1977 wire diagram and the oil low pressure warning light switch supplies a ground to the low oil pressure indicator in the tachometer. I am wondering if what you are disconnecting is the wire to the oil pressure gauge sending unit that indicates how much oil pressure you actually have instead of disconnecting the switch which lights the light. They 2 senders are usually installed very close together at the oil filter /pump housing.

[njspider]

Yup, it was the sender.

[spider2081]

Nice.