I have an 88 Ranger 2.9L, Automatic, 150K miles that has the CEL on while driving now. I will start from the beginning:
Last week the truck started idling rough and stalling at lights if I had the AC on. I changed the plugs, rotor, cap, wires, air filter, pvc, and breather to no effect.
On Tuesday it stalled several times on the way home from work. Everytime it dropped to idle it would stall whether the AC was on or not. At this time the CEL came on and stayed on. I checked the codes and got the following:
61 - ECT indicated 254 F/grounded circuit
After seeing the codes, I replaced the ECT with a new one. I then reset the computer. When I started the truck I got a CEL along with the same code.
I knew it would not solve the problem, but at the advice of a friend I used Intake Cleaner on the throttle plate. It helped some. The CEL light still comes on with the same error, but now the truck will idle.
To the point - any idea what to try next for the code 61? Since the new part did not fix it I was assuming that there could be a ground in the circuit, but I dont have a clue how to start diagnosing where it might be.
You should run the pinpoint tests, these determine the exact cause of the code. It sounds like you have a wiring problem, do you have a meter? I can send the tests to you from my 1988 Ford manual, send me an email with your email, remind me of what you need.