More or less what I thought....no I've never tried a motorcraft ICM. First one was a cardone that came with the new dizzy and then the warrantied ones they've always given me BWD ones. In the 8 or so months I drove it before the trans blew up I probably replaced it once every 6 weeks. Not too much of rhyme or reason to it. Was always while I was going slow/coasting or coming off a stop. Never on the highway
I've been kicking around the idea of just buying a new computer for ages. I just don't know if its worth it (we've all seen pics of the thing by now). The big problem with this is I'll never really know if its fixed. A few times I thought I had it sorted. And then it fried again. Where are these diodes if they're still on the harness? I'll take a peek the next time I'm out by my cousins. I'd assume they're fine though because I could go start it now if I wanted to.
actually im not sure if your would have them or not as I know they were on the early EFI. I keep thinking u have a 87 not a 89 some reason. I dont recall seeing the diode on my 90 F250 and when I just looked in the Electrical Vacuum Troubleshooting Manual for it, I didn't see them. on a 87 I was working on, it defiantly had them. when I google it ive seen people with 88 have them too. I know theres one for the IAC. not sure what else used it but I think theres like 3.
itll start fine if there bad. it just gets feedback that can come back and cause damage. I think the coil is to blame for the qfeedback. I know that theres diodes for the E4OD tranny that eventually got moved in the ECM after a certain year and using a newer tranny in an older truck will eventually fry something
theres one going to the IAC (which I had to rewire)
theres a big one by the coil
theres one for the A/C clutch
there might be more but these were the main 3 I saw. problem is these I don't think are sold anywhere. don't even think Ford dealership has them. just gotta find out the rating and wire one in. but if your lucky your truck wont use them externally