Tried to fix oil gauge, now tach isn't working (Page 1/1) Modesto APR 14, 05:56 PM So my oil pressure gauge would jump all the way to the right as soon as the key was turned on. I disconnect the pigtail from the sending unit and grounded the middle connection. Sure enough it jumped to zero. I plugged it back in (key on but not running) and it jumped to 40. When I killed the key it went back to zero and when I started the car it jumped back to 40. I let the car warm up to see if it lost pressure and it did slightly, so I went to go for a spin and noticed the tach now wasn't working. Also, I realized buy the end of the drive the temp gauge wasn't reading as warm as usual after a drive, it normally rests at the next large notch. Here is what my cluster looked like at the end of the drive with the car on. I read on another thread that on '88s the oil gauge and tach are "linked"? I have doubts the oil gauge is reading correctly, so I plan to verify with a mechanical gauge. The only other thing that changed is I have the trunk release switch out waiting on a replacement. Any help would be greatly appreciated! Modesto APR 14, 09:31 PM I unplugged the oil sending unit pigtail and the needle is at 0 when off and 40 when on... Patrick APR 14, 10:42 PM I had the same problem for a short while with my '88 Formula. The oil pressure gauge would peg as soon as I turned the key. The engine obviously wasn't attaining all that oil pressure before it even started. Turned out to be just a poor connection at the pigtail. Modesto APR 14, 11:02 PM Well, the question is now, should I try and fix it before or after I drop the motor? (99% sure my mystery sound is a broken crank)