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Original_MudButt
October 13th, 2017, 18:28
This is my daughter's '02 TJ, but it's the same motor and I don't belong to a TJ forum...

Two days ago, the "check gauges" light would come on at idle because the oil pressure gauge showed zero oil pressure. Once the Jeep started moving, as the RPM went up, so would the pressure. Max was bout 40 psi.

As a first step I had the oil and filter changed because it was time anyway. 20/50 oil and a WIX gold filter.

No change. Zero oil pressure at idle.

So I got a factory MOPAR sending unit and swapped that in.

Now as soon as the Jeep is started the oil pressure gauge goes up to 50 psi. at a normal rate.

BUT... No matter what the engine RPM and no matter what the engine temp (100-210 degrees) the gauge does not move. Not one whit. I can go from idle (about 750 rpm) to 4000 RPM and the gauge does not deviate AT ALL... 50 psi.

I know the obvious is to put a mechanical gauge on it, but we are leaving for Johnson Valley tomorrow. I may leave the Jeep at home until I figure this out.

Any thoughts??? HELP!!!

Jeep Driver
October 13th, 2017, 18:41
My guess would be that you got a sender for the idiot light and not one for a gauge.

Original_MudButt
October 13th, 2017, 18:57
My guess would be that you got a sender for the idiot light and not one for a gauge.
OOOOOOHHH!!! That makes total sense! Thanks!!!

Green Mesa XJ
October 14th, 2017, 07:19
I agree with Jeep Driver.
But beware that 4.0 may have the 0331 problem head, but being 02 might possibly have the good 0331 production or been replaced already


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lawsoncl
October 14th, 2017, 20:35
My guess would be that you got a sender for the idiot light and not one for a gauge.


Yeah, the on/off switch version is like $10. The variable resistance sender version, which tends to fail because it mechanically wears out, is closer to $50.

Original_MudButt
October 18th, 2017, 10:06
Yeah, the on/off switch version is like $10. The variable resistance sender version, which tends to fail because it mechanically wears out, is closer to $50.

Well, the one I bought from Amazon was $53 and change. I'm going to the dealer with the VIN tomorrow.

But beware that 4.0 may have the 0331 problem head, but being 02 might possibly have the good 0331 production or been replaced already

It's registered as an '02, but the VIN says it was built in 7-'01. Dunno...

We took it to JV and screwed around all day Saturday. Drove home Sunday. Zero issues.

I'll get to the bottom of this. Thanks all!:cheers:

JohnX
October 18th, 2017, 21:34
Well, the one I bought from Amazon was $53 and change. I'm going to the dealer with the VIN tomorrow.



It's registered as an '02, but the VIN says it was built in 7-'01. Dunno...

We took it to JV and screwed around all day Saturday. Drove home Sunday. Zero issues.

I'll get to the bottom of this. Thanks all!:cheers:
Production date is not the same as model year. Build date of 7-01 is probably a 2002 model year.


It probably is just the wrong sending unit...but regardless, you should get a manual gauge on there just to verify.