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yjrestoinprogress 03-20-2011 04:34 PM

Oil pressure gauge pegged.
Hi all, I just got everything on my motor back together and for some reason the oil pressure gauge is pegged high. Now there are two sesnors and I know a bad one could do this the one sensor has a blue and white stripe wire along with an orange coming out of it. the other sensor has a single one with just a redplug in wire on the top of it. Which on controls the gauge? If I put a test light on the sensor with the single wire on it the single wire will read hot with the key on. The blue wire on the other doesnt do anything when hooked to ground and the orange will read hot just like the other sender. Also none of this has any effect on the gauge reading.
Thanks dan

NAVYCHIEF 03-20-2011 05:03 PM

what does the gage do with both wires disconnected?

yjrestoinprogress 03-20-2011 07:28 PM

even with all the wires disconnected the gauge still stays pegged at high. which of the sensors control the gauge?

NAVYCHIEF 03-20-2011 08:41 PM

what engine and year? on my 4.0 the sending unit is on the rh side. the wire is gray/yellow stripe.

yjrestoinprogress 03-21-2011 11:47 AM

sorry guys i forgot to put that in there its a 1990 yj with the 4.2 in it. i bought it with a blown motor so i have no idea how the wiring was before i pulled the motor

Undead-89 03-21-2011 12:25 PM

There should only be one Oil sender unit. near the rear of the engine on the Passenger side if I remember correctly. The wire should be Light Blue/green.

yjrestoinprogress 03-21-2011 03:55 PM

My block has both of these on the right side of the motor Oil Pressure Switch | 1990 Jeep Wrangler 4WD 6 Cylinders T 4.2L 2BL | the one with two prongs has a BLUE/WHITE wire and an Orange wire in it the other one has a single red wire? The red and the orange wire are hot at all times

Undead-89 03-21-2011 04:05 PM

According to that page, the two prong one is for the idiot light and the single prong one is for the gauge. I'm gonna go double check mine.

Undead-89 03-21-2011 04:19 PM

Okay here are the results (done with the key in run, engine not started):

If you take a wire and short the two contacts together on the double prong unit, it sets some relay in the engine compartment but the gauge does not change.

If you run a wire from the lead going to the single prong unit to the chassis ground, it will cause the gauge to go to zero.

So the one you need to replace is the single prong one. (as do I, these used to cost 60 bucks, I think I will replace it now that it is reasonable.)

kik 03-21-2011 04:46 PM

My 89 4.2 sending unit has one wire and is in the shape of a bell for a lack of a better term. I replaced mine 3x. They seem to work fine for awhile and eventually peg out. Most times mine works great after everything warms up.

yjrestoinprogress 03-21-2011 07:26 PM

ok thanks guys ill try it and report back

schmidt311 11-01-2015 01:21 PM

YJrestoinprogress oil pressure gauge pegging out
Did you ever have success with this? Mine has been doing the same thing for years. Not an expert under the hood, so wondering if this is something a novice can do?

DREDnot 11-01-2015 04:24 PM


Originally Posted by schmidt311 (Post 22261857)
Did you ever have success with this? Mine has been doing the same thing for years. Not an expert under the hood, so wondering if this is something a novice can do?

Try buying a MOPAR replacement sender. It just screws in the hole. Mine works great, now.

Watson1970 11-01-2015 05:04 PM

Part number? Mine does the same thing.

DREDnot 11-01-2015 10:46 PM

Fill out your profile, or a sig line so we know what you have

marine_hm 11-09-2015 10:06 AM

I was going to start a new thread asking the same thing. Glad I didn't. This seems to be a common problem. I have a 2002 wrangler-X (4.0 I THINK) Can someone post a picture of the sensor so I know what I'm looking for? Is the sensor the most common problem for the gauge to peg-out? And as suggested in this and other threads, only going to replace with MOPAR parts.

Sensor - Sending unit? What?

schmidt311 11-11-2015 01:00 PM

Updated my profile on here. Do you know where this is located on the 4.2L 6 cyl?

DREDnot 11-11-2015 09:18 PM

This is where it is on the 4.2L. Side of the block towards the back...

It should be near the distributor on the 4.0L...

schmidt311 11-13-2015 11:02 AM

Thank you sir! That's one clean engine!

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