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I thought I had fixed my intermittent engine cut out with no restart after replacing the fuel pump. However, on my way in to work this morning the truck crapped out on me again. Sometimes it would turn over, catch, and sputter back to dead and other times it would just keep cranking with no start. I can hear the fuel pump running when it's supposed to. After sitting by the side of the road waiting for a tow truck for about a half hour, I tried to restart the truck and it started up and idled as normal. No check engine light. Drove it home but stopped by Vatozone first to have them pull any pending codes and the only thing that came up was P1639, Vehicle ID Block Corrupted, Not Programmed. Again, this is a pending code, not throwing a trouble light anywhere. Everything I read about this code indicates it shouldn't cause a no-start issue. What the heck is going on?
To throw a little more info into the mix, it appears the PCM is not the original. The case only has one screw holding it in and the nearby wiring loom retainers aren't hooked on. I haven't pulled the PCM yet since the truck is currently running as it should, but I think there is a label that says "Remanufacture PCM".
I had this happen on a 2008 with 6.4 diesel....I had to get as built data flashed the the pcm at the Ford dealer.
If new pcm in truck...was it properly flashed when it was installed? Is check engine light on....mine was on along with battery light.
Double check pcm connections to make sure they are connected properly and not loosing connection over bumps etc.
I'll check the screw on the harness connector. The fact that this truck has a reman PCM is news to me, so I have no idea if it was done properly. There is no CEL or any other warning light on. I have a better code reader on order that should be here tomorrow, we'll see if it says the same thing.
While I doubt it's related to the P1639 code, I did some accidental diagnostics to the truck yesterday that may have pinpointed my stalling/starting problem. On a return trip from Lowe's, I realized I forgot to grab some angle iron from their hardware department. In frustration I gave a moderate punch to the edge of the steering wheel. Immediately the radio lost power. After a few seconds it came back on. I'm not sure if anything else was affected at the time, but it made me think all of the problems could be explained by a failing ignition switch!
Ignition switch replaced, problem still happens. Started driving around with a code reader and the next time the engine quit, I immediately pulled over to the side of the road and plugged in the reader leaving the ignition on. The code reader was unable to connect saying it couldn't detect an OBDII PCM. Key cycled off back to on and the code reader instantly connected and showed no pending codes. At this point the truck fired right up and ran as normal.
Being pretty sure this is an indication of a bad PCM, I pulled it today to get the part number and found a Jet performance chip plugged into the back. I'm wondering if the chip caused a PCM failure or is something screwing with things?
And, after opening up the case, I discovered what might be the problem. This transistor near where the chip plugged in was bent over and appears to be barely making contact with the board.
And, after opening up the case, I discovered what might be the problem. This transistor near where the chip plugged in was bent over and appears to be barely making contact with the board.
Pick up another transistor, shouldn't be more then $1 from any website, desolder the old one and re-solder the new one. Good catch!
New computer in and so far the problem has not returned, though it was so intermittent it'll be a long time before I'm confident it was 100% the problem. Now, I'm not sure if it was partly symptoms of a failing PCM, a ****ty Jet performance chip, or a combination of both, but it feels like a whole new truck! Idles and accelerates much more smoothly, transmission shifts better, and I swear it has better pickup and go.
