I have a 1989 4wd truck and recently the oil pressure gauge quit working. I found that the wire was broke loose but not from the oil sending unit. I hooked the wire back up and the gauge was reading a really high pressure and when I went down the road it went all the way over to high pressure. Now when I crank the truck the gauge is reading nothing again. Do y'all have any suggestions as why might can fix this problem.

 

Test the pressure sending unit first. Verify that it's working, then check your wiring and the gauge. Or, you can work the opposite direction back down to the sending unit. Just grab a multimeter and work sequentially through it.

My gauge always reads low, even though the pressure is good.

 

I checked my wiring and it seems to be hooked up right. I am thinking I may need to buy a new unit

 

Is there a single lead coming off of the pressure sending unit? or is it several wires?

 

Anyway, with key on engine off, pull the cable off the sending unit. Check your gauge. It should peg. Then, if you ground it, it should read zero. (There's a chance I may be thinking backwards on this one)

If the gauge responds like that, your wiring and gauge are good, leaving only the pressure sending unit as the faulty component. If your gauge doesn't respond, you'll have to start looking elsewhere.

Let me know how it works out.

 

There is only one wire that runs from the oil sending unit. Update gauge still not working and when I turn the switch on I am hearing like a clicking noise which sounds like it is coming out of the shifter. I am not sure if this has anything to do with gauge or not. Any advice

 

More details needed. Just work things one at a time.

Did you get the wiring to the gauge tested? Once you've got that, give details on the clicking sound. Engine running or off? Are you talking the key switch? Or a different switch? What sort of clicking noise?

 

The wire has power. The clicking sound happens when I press the brakes and it sounds like it is coming from the gear changer. It does when the key is on but engine off and it also does it when key is on and engine is on. The noise sounds like a pen tapping on a table. I started hearing the clicking noise a couple days before then the gauge stopped working. I think I will just end up taking it to someone who understands the wiring. I am not real familiar with all them wires.