Just picked up a 91 CRX in decent shape, but the temperature gauge doesn't work. Every once in a while it will fluctuate wildly, but mostly it just stays on cold and doesn't move at all. Any ideas on what could be causing that?

 

Anyone know?

 

Most likely the sending unit. its under/near the dizzy. Check the plug on it it could be loose or corroded and making a poor connection. Its possible its gauge in the cluster, but much more likely the sending unit. If someone has done a swap in the car or if wires looked chopped up and taped back together anywhere it could be a wiring issue. check under the dash if an alarm was ever installed at any point they might have cut into some wires they shouldn't have.