No oil pressure light

[Hilltopper46]

Would the brain trust here mind confirming what should be a simple question? Should the oil pressure light come on when the key is turned on, but before the engine starts?


All the following testing was done at the switch / sender / sensor:


Engine not running - No ohms (or very low ohms)
Engine running - infinity (OL)
Key on - engine not running - 0 volts
Key on - engine running - 12 volts (as though bulb in the light is good)


Thanks in advance.

[Filmcamera]

Yes it should, with the ignition switch in the on position but the engine not running the oil pressure light should be lit up in red.

[kioolt]

There's no oil pressure before you start the engine so yes it should be on.  All of your readings indicate that your bulb is good and also your switch.  Were you just asking to confirm or is you light not on with the engine off?

[kioolt]

I've given it a little more thought.  Your reading do indicate that the bulb could be ok.  Any resistance other than an open circuit in the circuit from the oil pressure switch, through the bulb , to the battery + would give you 12 volt at the switch with the engine running.  A better check would be to check the actual resistance from the plus side of the bulb to the oil pressure switch with the wire off of the switch.  If you read a very high resistance then you need to find the bad connection or bulb.

[Hilltopper46]

OK - thanks for the confirmation on the operation of the light.


I shorted the wire to ground and with the key on the light glows brightly so it is the switch.


I went back out after dinner and turned off the auto-range on the multimeter and found that the resistance through the switch is ~40 ohms with the engine not running.


Thanks for the help.