85 RX-7 that sat in the woods for about 20 years, trying to get it back in working order. One of my main problems is the temp and oil pressure gauges not working. Ive replaced both, Ive tried to ground out the wires to see if I get a reading at the gauge, Ive traced the wires back to make sure theyre in good shape. Nothings has worked. I should mention that when I got the car nothing on the cluster worked, I had to scrape away corrosion and rust on the back of the cluster at every connection, everything but the two gauges came to life after that. Anyone have any ideas?

 

Take the cluster off the car and check for continuity across the temp and pressure gauge terminals. The gauges have a very thin wire that creates an electric field which moves the needle. If that very thin wire broke somewhere you’ll have zero continuity. You will need to remove the gauge face to see the thin wire and make any repairs.

 

Thank you for the reply, I started into your suggestion but cannot figure out how to get the gauge face off completely, its unbolted and loose, but the needles are in the way

 

I figured out how to get it off haha. I inspected all the wiring and the solder points everything looked perfect except a small amount of corrosion at the base of the solder points, but nothing that should stop continuity

 

Glad you got it off. Did you verify continuity with an ohm meter?

 

I did, 43 ohms at the oil pressure gauge and 54 ohms at temp gauge

 

Sounds like you have a break in the wire harness somewhere then. Did you ohm them out as well?

 

Yes I did, very little resistance. I should have mentioned, there is four wires that run in a bundle to the temp sensor and oil pressure sensor, one for each sensor as well as a black and yellow, and black and green. The two black ones have been chewed by mice and I have zero clue what they run to. I've tried to look at wiring diagrams but I struggle to decipher those