Testing the Thermostat and/or Thermostat Wiring

[Fried_Chicken]

I just got a service engine soon light on the dash. Pulling codes gave me P0599: "Thermostat Heater Control Circuit High".

The problem is either with the thermostat, or with the wiring for the thermostat. Is there a way to check either relatively easily? I just replaced the power steering pump/reservoir and that had me dicking around in the area of the wiring. The wiring on the thermostat is pretty corroded.

Worst case I'll just replace the thermostat and see what's what.

Thanks!

[Dave1027]

The wiring on the thermostat is pretty corroded.

I'd try cleaning up the connections with something like Deoxit then reset the code to see if it comes back.

[Fried_Chicken]

I'd try cleaning up the connections with something like Deoxit then reset the code to see if it comes back.

No dice; time to replace the thermostat.