oil pressure gage messed up - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 08-31-2003, 01:12 AM   #1
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Default oil pressure gage messed up

It usually reads around 700-800 KPA at any rpm or speed, sometimes it workes its way to the half point but not usually, also it will pin itself at the Max 835 KPA sometimes when i turn the key on without the car running......sending unit??
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Old 08-31-2003, 09:31 AM   #2
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Hmm... Need a kPa to psi conversion here...
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Old 08-31-2003, 11:22 AM   #3
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Check the connections at the sending unit... it'* right above the oil filter and has a 4-wire connector attached to it. You should be able to reach it from above, no need to crawl under the car.

Also try tapping on the gauge cluster - my temp. gauge does something similar every now and then and when I tap on it it fixes itself.

I had the exact same thing happen to me after swapping my engine, but it was because the new engine I put in had the oil pressure switch (for an idiot light) instead of a sensor. Replacing it with a new sensor fixed the problem.
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Old 08-31-2003, 03:49 PM   #4
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Quote:
Originally Posted by fuddyduddy121
Hmm... Need a kPa to psi conversion here...
Its going to the max alll the way so 120psi?
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Old 09-02-2003, 12:33 PM   #5
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Default Re: oil pressure gage messed up

Quote:
Originally Posted by SSEimatt93
also it will pin itself at the Max 835 KPA sometimes when i turn the key on without the car running......sending unit??
You mean that it goes to maximum and _stays_ there, right? All the gauges will do that momentarily at startup as a proveout, but they should come right back down again immediately.

I'd check to see if the wire to the sending unit is shorting to ground somewhere. Also try unplugging the wire at the sensor. If the gauge stays pegged after that, look for a short to ground in the wire. If the gauge does _not_ peg after that, replace the sending unit.
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Old 09-03-2003, 06:50 PM   #6
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okay i un plugged the sending unit wire, and started the car and the gage still pins its self at the maximum, now lol wiring and all that has got to be the most difficult part of these cars especially since im more of a mechanical than electrical person lol
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Old 09-03-2003, 10:21 PM   #7
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If the resistance in the sender is zero ohms, you will get zero pressure. If it is 90 ohms, you will get max pressure.

So if you disconnect the sender, you should get max pressure. Try a jumper wire between the two wires on the harness. You should get zero pressure.

And while you are under there you may want to replace the sending unit.
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Old 09-04-2003, 02:03 AM   #8
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so basically cross positive with negative on the harness?
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Old 09-04-2003, 02:46 PM   #9
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Quote:
Originally Posted by SSEimatt93
so basically cross positive with negative on the harness?
Oh, heck, there I go trying to give advice without actually _looking_ at the part in question...

The oil-pressure sending unit on this car has _two_ wires? I was under the impression that it was just variable resistance to ground, and a single-wire sender. You're sure you're looking at (and disconnecting) the right component?

Anyway, yes, grounding it (or shorting its wires together, if more than one is present) should provoke some sort of reaction from the gauge. If it does nothing but stay pegged, I'm thinking the problem is somewhere upstream in the wiring harness...
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Old 09-04-2003, 03:06 PM   #10
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Yes, jumper the wires on the harness. One is a ground and the other is the input signal to the PCM.
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