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Bad PCM?

12755 Views 5 Replies 5 Participants Last post by  DavidD
My 97 died the other night. No rpm's while cranking, no wait to start light. Check engine light on. Fuse 22 was NOT blown, nor were any others (except the trailer battery charge fuse #18, explained by a recent trailer wiring job) All the fuses have power to them and thru them and all were checked with a meter. I tested the 6 relays at the UH fuse location. I put in my spare CPS. The batteries are very old, but it cranks strongly and my smart charger indicates no problems with them. There were no intermittent problems leading up to this. After reading lots of threads, it seems the combination of no tach and no WTS light and no blown fuses point towards the PCM. I do not have a scan tool, but may have to buy one.
Have I missed anything? Are there any other relays I need to test? What does a PCM cost and who has the connection that can save me $$. Speaking of connections, are there any I need to check, other than at the PCM itself. Do PCM's just abrubptly fail like that or is it likely something shorted it out, even without blowing a fuse? I'll try anything you all can throw at me. Thank you!
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Tesla, I had a similiar problem I haven't posted back on yet. I know I had no rpms on tach, had the WTS light, and IIRC no CEL. Pointed straight to the CPS, which in fact was the circuit affected. I HAD a chip in it. After everything else failed I removed the chip & it started. I still had to replace the computer because the CPS circuit became intermittent. Looking at the chip I'm convinced one of the contacts became weak causing the problem, even though it was very secure prior to removing. The computer I bought from O'Reilly's claimed it needed to be "programed" by the dealer. The shop I found (not Ford) told me they updated calibration, but as I understand it they pulled my program TDE0 and installed it on the new one. Still plan to check that for sure.
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