So Im trying to finish up all the little stuff on the car after swapping the engine. Its a 92 z28, I got the cooling system done last night and was letting it run and noticed that when I turned the lights on my oil pressure gauge was dropping then coming back up. It was only doing this when I would turn the lights on. I used the 98 oil pressure sensor and wired it to the c100 and then just grounded it. I dont know if maybe its not grounded well enough or what is causing it. I know that the couple times that I drove the car before the swap when it had the 305 tpi still, the oil pressure gauge would stay pegged for 20 to 30 minutes then read normal pressure. So I dont know if the gauge itself is bad or if its the sensor. Not sure if I messed something up or what. Anyone have this issue, or have any suggestions? As normal any help is appreciated.

Thanks,
Jay

 

Your easiest, and obvious, first step is like you said: Check your circuits first. Anything else dip or dim after you turn the lights on?

Before I pulled my engine, when it ran, even with the HID's it dimmed for maybe half a second before my alt picked up. My 79 was a different story, though. lol

 

Haha, nope thats the only one thats doing anything out of the norm. I just ran out of time working on it last night so I didnt have a chance to check it yet. I was just curious if anyone else has had that issue or not.

 

So I unhooked the ground for the oil pressure sensor and the sensor pegged as I figured it would. So I am pretty sure it was the ground I am going to find another spot for it tomorrow so hopefully that solved the issue. I forgot until I just went and looked at it, but it was causing the tach to move also. With the ground un hooked the tach stayed where it needed with the lights on or off.

 

Your headlights shouldnt affect anything. If they do, Id check their grounds. Theres one behind each lamp. Also check the cluster ground from the c100. It gets forgotten frequently and with the external ground, the rest may be grounding through the OPSU

 

Thanks Pocket..you were right lol. Hooked up the mechanical gauge and looked down and sure enough I saw the ground peaking out at me at the c100. Thanks man, I appreciate it. Good news is I have oil pressure!