Hi guys, i've got a cat 301.8. The temp guage stopped register a temperature so i changed sensor and it seemed to work the first time i started it and now i tried again today and it's just staying below cold again. When i rev engine up it bounces a little bit but still doesn't register a temperature. Anyone have any other ideas i can try?
Not knowing your machines PIN / S/N I took a guess and the one I looked at showed the wire connected to the temp sensor to be #441.
I would start by disconnecting this wire then turn the key switch on then while someone watches touch the wire to a good ground on the engine. If like most temp gauges should read full hot when disconnected then full cold when grounded. That said Cat could have it set up the opposite!
Either way you should be able to get gauge to go from one extreme to the other if wiring and gauge are good. If you can't get it to react at the engine end you could try the same test at the gauge. There should be three wires connected there, on black ground, the other would be hot(12 volts with key on) and the other one should have the same number as the wire at the sensor, likely 441.
Check to see if you have 12 volts at the wire to the ignition switch, most likely a green wire with yellow tracer. Disconnect the 441/sender wire and use a jumper to alternately ground and unground the sensor gauge should react by going full hot then full cold. If gauge acts right when tested at the gauge but not when same test is done at sensor problem is in the wiring.
If you can give the S/N I may be able to give some ideas and if you Private Message me with an email I could try to send you the wiring diagram for your machine.
