Questions and Answers
Fried Ranger PCM
Q. Hi, being young and foolish and a do-it-yourselfer I tried to put a remote start on my 1993 Ford Ranger 4 litre V-6. Knowing that it's not safe to install one on a manual transmission vehicle, I figured out my own safety features so that it wouldn't be started in gear.
But not realizing that there is a clutch safety switch that needs to be pushed in before the engine will crank. I unplugged the wiring harness on the clutch switch and tried to figure out how to bypass it and started probing the wires with my test light. A little while later I started my truck and it ran terrible with fluctuations in the rpm and the service engine light come on.
At one point I couldn't even get the engine to start. I looked in a shop manual at the wiring diagram for this vehicle and noticed that one of the wires I probed, in the clutch safety switch harness, went directly to the PCM. Is there a chance that I fried my PCM even though my vehicle runs sometimes. I was probing this wire with a test light and the ignition was on, but the engine not running, did I cause a short?
I have since removed all traces of the remote start installation in hopes of that the system would repair itself, but no luck. If you have some experience with PCM's please e-mail me with some suggestions or answers.
A. Ahhh yes, I too was once young and foolish. I still remember my first tune up on a yellow 1967 Chevelle with a 307. Boy, did I screw that up.
Anyway, chances are good that you did fry the PCM. It is not recommended to probe PCM circuits with a test light since some of them are low voltage circuits. When you step on the clutch, the switch completes the starting circuit and sends a signal to the PCM that the clutch is, indeed, depressed.
If you do have everything back to the way it was before you started, replacing the PCM would most likely fix your problem.
Additional Information provided courtesy of ALLDATA
