My gen 1 PCM in the 89 would not show any codes when I had no start problem. Read the faq Crazy is refering to, and by all means check the splices. After a lot of hunting I had Mrs.N. crank the key while I jiggled wires and did get it started by jiggling the feed harness to the PCM. I replaced the PCM because the terminal pins were worn because the attachment harness was not tight. I could actually move the harness and stop the engine. Its worth a try. After I replaced the PCM I had codes ,overdrive was back and to my surprise the cruise control started working, (first time since we had the truck).

 

first check splice under battery box little black wire replace splice even tho it looks good if that doesnt work check wires around transfer case may have shorted out on drive shaft an blown pcm mine ran fine on a sat. an wouldnt start on mon after 2 wks new sensers, pcm and everything else i i could think of 500.00 later a 5cent splice under the battery box a month after that wires around trans case an another new pcm

 

I went through all that on the 89 except the splices were good. My big disapointment was the replacement PCM from NAPA was defective, I ended up with one from a junk yard that fixed all problems. I MIght add that I was told by the local Dodge Dealer's Service Department " It's runs, we don't see these old trucks anymore".