notop46

Hi All,

I have a sweet '90, 4.0, 5 sp, 4WD with 230k miles. Only issue I have not been able to resolve since buying it is the Oil pressure and Volt Meter gauges going dumb. The oil pres goes past 80 and the ammeter sits at less than 9V. I have checked the Haynes manual wiring diagram, but could not find a common wire that is used on both gauges.

I don't want to tear the dash out on a wild goose chase.



Any suggestions?

mike albo

my oil pressure gadge did the same thing,check the end that is plugged onto the sending unit,mine was broken inside the terminal,changed the end,fixed it.

TheNerd

You may also want to inspect your main wiring harness connection through the firewall. With your manual, the clutch master cylinder is positioned in such a way that if it leaks any brake fluid at all, it drips right onto the main firewall wiring harness. Brake fluid is nasty stuff, and will eat away at the plastic connectors, eventually leading to poor connections, corrosion, and all sorts of electrical gremlins. The source of all my electrical problems has been that. Especially when talking about the voltage gauge, which is wired in such a way that it is highly succeptable to influence from any short in the system.

As for the oil pressure gauge, as mentioned, when it fails, it pegs on the high side. So if you are getting 80 (or intermittent 80), you are probably either looking at a bad connection to the sending unit, or a bad sending unit. Officially, you should check your oil pressure with a mechanical gauge to verify that you really aren't getting that high of pressures (although, I have heard that the oil pump has an internal bypass for any pressures over 75psi, so it is highly unlikely you are really getting those oil pressures).

notop46

Thanks, I will check the connectors and the oil pressure. My oil pressure has been good, but not 80 psi good.

notop46

Hi All,

After about 3 months of not working, both of the gages suddenly started working again at the same time. I can not explain it. I never found out what caused the problem. Again, if there are any suggestions as to what would cause both to die and come back at the same time, I would appreciate the input.

Cherokee forum rocks!