Bad PCM???
 

Ok here is my problem...I have a 96 F-150 4.9 4x4 standard cab long bed. The truck wont pass smog. Why, you ask? The engine runs fine, no check engine light ( and the light does work ). The problem is with the system monitors...they wont activate or whatever the technical term is for it. I took it to the stealership and they plugged it in and cleared the computer. The tech proceeded to burn up a half of a tank of gas putting it throught the drive cycles. They called me up and said it was already to go would you like us to smog it? I gave them the go ahead and when they went to smog it OMG the system monitors arent ready. They told me its an internal fault in the PCM and told me a new one is 440 dollars plus one hour installation. Has anyone had this problem and is it really the PCM? Or is this dealer bull**** talk because they really dont know whats wrong with it. Im going to fix it myself with a reman PCM for 140 bucks, but I would still like some imput before I throw money at it. If you need more info on my problem for an accurate diagnosis let me know. Thanks for you time, Chris.

PCM failures are not that common. The only positive way to check the system is with a breakout box, and not many shops have one. But before you replace the PCM try this, Disconnect the battery unplug the PCM inspect the plug on the cable and the PCM. Look for corrosion any damaged wiring along the harness. Make sure PCM is firmly attached to the vehicle and that the case is grounded well. Make sure all grounds to engine are clean and tight. Reconnect the PCM then the battery and retest. It could save you a few bucks.

Pat

pcm
 

Thanks for the imput. Between then and now I took out the PCM to go get a replacement. The pins were spotless, and I checked all the ground points. Everything looks good. You would think the dealership would have all the equipment to do a more complete check. The truck only has 59k miles and its super clean, no rust and it hasnt been driven hard (bought it off my father). Ill just throw a new PCM in it and see what happens. Oh yea Kragen said they had it in stock but when I drove 10 miles to the main store they had to order it... oh well. The PCM is remaned by cardone so we'll se how that goes...thanks again