# Having problems with oil pressure gauge



## GTO52 (Oct 25, 2018)

Hello,
I'm wiring my 65 GTO with rally gauges. Having a issue with oil pressure gauge. Looking at the gauge from the back, which terminal is for the power? As soon as the key is turned to the on position it pegs the gauge. I have tried a different gauge and 2 different (new) oil sending unit a and get the same results. Any help would be much appreciated. 
Thanks


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## Roqetman (Aug 31, 2015)

I would say most likely the OP gauge has lost it’s ground or is connected incorrectly. If it’s factory gauge it should be a one way plug. Aftermarket gauges have 3 terminals, +, -, signal/sender.


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## GTO52 (Oct 25, 2018)

I'm using a stock GM Rally Gauges, with 2 prongs. No Teflon tape or sealer on oil sending unit (it's for a gauge not light). Have power to the gauge, coming out of the gauge and at the sending unit. The wiring is kit I'm using is from American Autowire, the diagram with the kit shows the power on the right side of the gauge looking at it from the backside. Also it doesn't show a ground wire on the pod that holds temp and oil gauge, but shows one on the main cluster. Thanks


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## Roqetman (Aug 31, 2015)

GTO52 said:


> I'm using a stock GM Rally Gauges, with 2 prongs. No Teflon tape or sealer on oil sending unit (it's for a gauge not light). Have power to the gauge, coming out of the gauge and at the sending unit. The wiring is kit I'm using is from American Autowire, the diagram with the kit shows the power on the right side of the gauge looking at it from the backside. Also it doesn't show a ground wire on the pod that holds temp and oil gauge, but shows one on the main cluster. Thanks


Considering everything you’ve checked, I’m say the op gauge is bad or the wiring is reversed. Is the black wire to the sending unit? You can try reversing the plug and see what happens... be sure to check your fuses.


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## O52 (Jan 27, 2019)

Pink wire to the left, blue wire to the right














rally gage wiring Schematic - PY Online Forums - Bringing the Pontiac Hobby Together


rally gage wiring Schematic 64-65 GTO Tempest & LeMans TECH



forums.maxperformanceinc.com





*You need to insure the gauge housing is grounded







*






1965 Gauges - PY Online Forums - Bringing the Pontiac Hobby Together


1965 Gauges 61-66 Big Pontiac TECH



forums.maxperformanceinc.com





*Misc Info*






65 Engine wire harness & gauges info needed - PY Online Forums - Bringing the Pontiac Hobby Together


65 Engine wire harness & gauges info needed 64-65 GTO Tempest & LeMans TECH



forums.maxperformanceinc.com










68 Rally gauges - PY Online Forums - Bringing the Pontiac Hobby Together


68 Rally gauges 68-69 GTO Tempest & LeMans TECH



forums.maxperformanceinc.com


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## GTO52 (Oct 25, 2018)

Thanks for the information and diagram. I'll be working on it tomorrow.
Thanks again


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## 68redbird (Jan 20, 2021)

GTO52 said:


> Thanks for the information and diagram. I'll be working on it tomorrow.
> Thanks again


Hey brother I’m having the exact issue. I just came across your post from last year. I’m curious to know if you tried as suggested adding a ground directly off one of the screws on the back of the pod and did this work?


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## GTO52 (Oct 25, 2018)

The wiring diagram that 052 sent me was the the problem solver. It showed the correct wiring location on the terminals. The diagram from American Autowire was opposite location of the wires and was not correct. The ground was not the issue. Hope this helps.


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