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Oil pressure gauge wiring issue

79Dave

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Hey guys,
First time on here, so go easy on me please. I’ve installed a saas oil pressure gauge and sender unit using an adaptor to also keep the oem item as well. It all works well until I turn the A/C on and the gauge drops to zero? It also drops and/or fluctuates when any lights are on...being blinkers, headlights and brake lights. Any thoughts?
 

lowandslow

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Sounds like a bad earth.
 

someguy360

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I have a SAAS gauge in mine too and I have the same problem.

It's a bad earth on the gauge end not the sensor (I've moved the earth on the sensor with the same result). I'm just too lazy to pull all the wiring out again. Try a better earth for the gauge.
 

wildfiremaint

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Hi, If your sender has a single
wire connection then probably a bad earth through the various brass adapters / t-piece to the engine block.
You would be better off with the SAAS 2-wire sender as per the pic.
Cheers.
 

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79Dave

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Thanks guys, it is a 2 wire sender which I’ve earthed to the motor, the gauge I have earthed to the chassis under the dash. Originally I had it earthed spliced into an earth wire behind the dash cluster. Both positions have given me the same issue. What if I earth the gauge to the same earth point on the motor I did the sender?
 

79Dave

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I have a SAAS gauge in mine too and I have the same problem.

It's a bad earth on the gauge end not the sensor (I've moved the earth on the sensor with the same result). I'm just too lazy to pull all the wiring out again. Try a better earth for the gauge.
Hey mate,
Thought I’d let you know that I earthed the gauge to the same point as I earthed the sender which was at the rear of the passenger side head on the 13mm bolt which also earth’s the wiring harness and my gauge is now working perfectly. Hope this helps you too
 

07GTS

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if u have a two terminal sensor (above earth type) then u will get best results with the earth from the sender to the earth wire on the gauge, then u have the earth and sender wire straight to the gauge and it will be on its own loop and wont get affected by any other wiring issues, just make sure the gauge has good earth/power also
 

79Dave

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if u have a two terminal sensor (above earth type) then u will get best results with the earth from the sender to the earth wire on the gauge, then u have the earth and sender wire straight to the gauge and it will be on its own loop and wont get affected by any other wiring issues, just make sure the gauge has good earth/power also
Thanks mate, that’s basically what I’ve done now. Earthed both the sender and the gauge to the same bolt on the engine which I guess is also creating its own loop plus being grounded to the engine. It seems to have solved the problem
 

07GTS

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using bolt on engine still can have issues best to have it as u do but just a good chassis ground, if u have a poor earth to engine then its going to have an issue but having no connection to the engine only chassis takes any engine issues out of it, see how it goes but any more issues then just change it to chassis
 

79Dave

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using bolt on engine still can have issues best to have it as u do but just a good chassis ground, if u have a poor earth to engine then its going to have an issue but having no connection to the engine only chassis takes any engine issues out of it, see how it goes but any more issues then just change it to chassis
Thank you again for your help mate, I’ll keep that in mind should any problems occur again.
 
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