Ok what's up guys. I've looked for the past few days in and off and can not find the correct wiring diagram I'm looking for.

First let me tell y'all what's going on

Oil pressure gauge quit working. Replaced oil pressure sensor (OEM), still no good. I knew I had oil pressure so I didn't worry about it for a while. I just got done with a complete rebuild from the cab forward, new engine, clutch, re-did the wiring harness, repainted frame and tons of other stuff. While everything was out and redoing the wiring harness checked all the wires and they were good. Cleaned all grounds and replaced all of them except the little junction boxes that mount close to the frame next to both lights.

Installed new instrument cluster, thinking maybe the gauge itself is bad. When turn power on the gauge does the swipe from high to low, on this one and the original cluster. But wanted to go ahead and replace it to cover every possibility.

Just got the car all done, everything back together, first start, still no oil pressure/cause not working.

I text continuity between the 3 wires from the sensor connector to PCM, all 3 wires good. All connections for sensor connector/pins feel tight.

Just installed another new oil pressure sensor, still no good. So now it has to be a issue somewhere between the PCM and the instrument cluster wiring. I have wiring diagrams of the PCM, but I HAVE NOT BEEN ABLE TO find the diagram of where the signal from the PCM TO THE CLUSTER for the oil pressure gauge is. I'm wondering if it is with the data line, and the cluster converts the signal to the gauge.

The only other possibility i could even even come up with is when I was ordering parts from my wholesaler, I also saw there was a oil pressure sensor connector with a pigtail aviable. Is that a common issue? All the connections and wires look fine and tested fine, but that's the only 2 options I still have left that I haven't replaced is the connector itself and what ever is between the PCM and cluster.

So im looking for wiring diagrams that show where he oil pressure gauge in the cluster gets it signal from or if anyone has a idea.

THANKS!

 

Sorry for the few type errors/spelling, using my cell phone and it's a pain to edit with it, lol

 

Thanks for the print-out that is exactly what i'm looking for. Im going to test the wire between PCM and cluster. Also thinking about trying to replace the connector. If that doesn't do it i'm just putting a separate gauge in it, lol.

 

Well my fuel gauge does not work either, but the code is for 5V ref. for the fuel level issue. But i'm thinking that is another issue in its own.

My coolant gauge does work.

But i do see what your talking about how the three would all not work if it was the one wire. So with that being said the only thing i'm thinking is it could be the connector, because I've done everything else I can think of. I'm going to replace the connector tonight and see what happens i guess.

The strange thing is that every now and then it does work for about 1-2 seconds then turns off again.


So say this does not work, can I get a electrical aftermarket oil pressure gauge and just wire into the factory sensor signal wire?

 

MAN,,,,,,,, Get a digital VOULT METER and see if you have 5 VDC reff signal. Then measure the LOW Reff pin to battery ground. If you have LOW Reff and 5 VDC, you should be able to see a signal voltage some where between 1.XX and 4.XX VDC on the output pin/wire.

I had a NO OIL PRESS Issue (actually had oil pressure) and it turned out to be an issue with my FAST 90 MAP Sensor relocation harness. It got plugged in backwards and killed the 5 vdc reff voltage. Swapped the plug around and BINGO.

You can also look into the connector and see if the FEMALE PINS are spread apart. If they are, they may not be making proper with the male pins on the sensor. The proper way would be to conduct a pin PUSH PULL TEST with a spare male pin into the female pins.

 

Bill, I have done the push pull test and everything seemed on, and i even slight bent in the connections to try to tighten it. But i do have a new connector that i'm replacing today to see if that does anything.

Can you go into a little more detail as to what happened with the map sensor relocation. I have a L92 manifold with square ports so the MAP sensor is on front, and i do have a relocation harness inline. If it is backwards, does it not have any other issues? I thought the 3 wires for the oil pressure sensor go directly to the PCM, so I'm not sure how that would effect the oil pressure sensor.

 

Also when your talking about the Pins, there is a 5V ref / Signal / Ground. When you say the LOW REF pin, what are you talking about. Thinking the power should show 5v, ground 0v, and signal will be between the 1-4 or so, guessing higher voltage the more pressure it is reading.

 

The Low Reff is the NEGATIVE return path for the module/sensor circuit. All of our modules use a discrete ground return path instead of a chassis ground.

So, In THEORY, you can read the low reff continuity to chassis ground but, you will get some very high resistance readings. As long as each module has proper power and a proper module power path, the low reff should read some continuity.

You're logic on the sensor output is good..

 

Here are a few pics of what I've been doing. NEw block/motor, drivetrain, rebuild wiring harness, repainted frames, redid fenders, new twin disc clutch and tons of other stuff. It's all done, just waiting on front body parts back from my body shop and a tune. Just trying to finish off these few little issues I've had since I got the car and ready for a tune 👍🏻

 

And my helper building the motor 😜

 

The harness I had was able to be inserted into the OEM connector two ways. After I found out there wasnt any 5 VDC Reff, I found that the 5 VDC feed other sensors. When I checked MAP, the connector wire colors didnt match up to the jumper haraness wire colors. Flipped it over and all was well. WHEW!

Yes, other things didnt work too but NO oil presure trumped the other crap and the engine still cranked, and ran.

Bill

 

Ok, well replaced the sensor connector, still no good. Went on a test-drive and the gauge jumped up/down very quick about 5 times then stayed off for the rest of the drive.

Scanned system and found

P0522 EOP Circuit Low Voltage

P1635 5V Reference 1 Circuit.

Where do you think I should start checking? I just found something about the map sensor being tied into it for the 5v reference?

I have already disconnected the PCM and the EOP Sensor and tested continuity between the three wires and it tested good. Not very sure what the next step and far as what can be effecting this

 

Start at the wiring harness the runs along the top of the drivers side of the engine. Look where it bends around the fuel rail bracket at the back of the fuel rail. Sometimes the wires get damaged near that bracket.

If any of the other sensors connectors or wiring are damaged, you will loose the 5 VDC reff.


BC