PCM Question........

Keep the faith, fat. If it lasted 18 years, why would it go bad now? Don't tell anybody why you believe your's is no good. Maybe it's just a bad connection or the nut at the wheel. I suppose you could have one of the parts stores check it for you, but they are sometimes wrong. It's time to just start changing parts until you hit on the bad one.

Mfat, Yes PCM's do go bad. Especially since yours is 18yr old. At that point it becomes like a bad step child that wont leave home.. LOL Although I am with the other guy on wondering why you think yours is bad? On the 88 it is goin to be EEC IV so you might want to just go to a shop and have them check it out. Keep in mind though, that there are alot of sensors that tell that PCM what is goin on, and if they are feeding bad info to the PCM then it will act like its bad, but its just a sensor in that case. Trust me, have someone with a scan tool check it out and see. Hell the truck just might need a tune up. It is 18yr old afterall.. LOL

<<Trust me, have someone

Hey! Well here`s the scoop: I just bought a 1988 Ford F-150 with a 4.9L 5 speed, and It has this crazy electrical problem. I knew that the truck wouldn`t run before I bought it, but the price was right ($500.00) with 118,000. The truck will not start and has weak spark. The distributor module has been replaced with no luck. If I leave the key in the "On Position" the fuel pump will run erratically, and the fuel pump relay "clicks" very quickly and erratic. Under the washer bottle, there is a wire harness that runs under it, and branches off on top of the left front wheel well with 3 connectors. The biggest connector with

12 pins (roughly) was corroded. I cleaned it, and still no luck. So then I inspected the other two connectors that are right next to the 12 pin connector, and they appear ok. Is there a common break in the harness? In that harness, is the wiring for the coil/distributor/and fuel pump together? Visually inspecting the harness, it looks ok. The truck seems to "flood" from cranking because the fuel pump is always energized. Smoke does come out the tail pipe, so there is little spark. I replaced the distributor module, and the pickup inside the distributor, still no go. I replaced both EEC relay, and the fuel pump relay, still no go. SO it leeds me to believe it`s the PCM. I took it apart, and nothing looks burned, but what else could it be? I have all my grounds, and power sources at the relays and so forth. I even replaced the pigtail on the front fuel pump. I`m at a loss!!!!!!!!!! Thanks,

...mfat

<<Maybe it's just a bad connection or the nut at the wheel.>>

What do you mean by that?

<<It's time to just start changing parts until you hit on the bad one.>>

Hahahaha i`m doing that now, but the parts arn`t cheep! That distributor module was $123.00! I can get a used PCM for $75.00 Is it worth a shot?

...mfat

I was just having fun, mfat. I'm against just changing parts and believe you should have it scanned for nothing at the parts store. However, If I have a vehicle that I intend to keep, I actually don't mind some parts guessing on items that commonly go bad. I save the old parts and eventually try to use everything up. It's nice to have extra parts to swap in when a problem develops.

Guys, The PCM fixed the problem. It was causing loss of ground throught the harness. I got a junk yard PCM for $70.00 she fired right up. SO HAPPY!!!!!!!!!!!!

!!!!!!!!!!!!FORD!!!!!!!!!!!!!!!!!!

...mfat