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01 f350 starting issues

683 views 5 replies 2 participants last post by  Justin@DP-Tuner 
#1 ·
Hey guys I'm new to the diesel world and have some questions...To start off with my pickup wouldn't start one day and I noticed I didn't get my wait to start light and my programmer never turned on. I cycled the key on and off a few times and nothing changed so I called my mechanic and he walked me through a few things and after I pulled my pcm fuse and checked it and plugged it back in everything fired normally and the truck started...didn't think to much of it until it did it again like a month later but this time it happened to be at the ford dealership we plugged it in to the computer and got a couple of codes the mechanic wasn't familiar with saying communication error from pcm to idm. I changed the idm and it didn't help the problem we pulled the wiring harness between the idm and pcm and it checked out fine so we then unplugged my programmer and it started working so I thought my programmer was doing something funny. drove it home when it was completely back to stock no programmer hooked up and it did it again so I let it sit over night went back out and tried it and it all worked great again so I hooked my programmer back up to see if it would do it again and nothing hooked and unhooked it put it on tow mode that i usually drive on and it has ran great ever since...lastnight i drove it home from work which is about 20 miles and it ran flawlessly turned it off ran inside for about 20 minutes went back out to leave and when i went to start it this time my wait to start light came on i can hear the relays click but it just turns over and wont start i tried it a few times...my tach moves up it did seem like my wait to start light went out quickly a couple of times but I'm lost and it seems as though the mechanic at the dealer ship is lost...am i looking at needing a new pcm or a sensor somewhere? any help would be great..Thanks!
 
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#3 ·
I got the same code I have been getting p1670 which from what I have read is communication error from idm to pcm...I have already tried replacing the idm when I had it not starting and it didn't start with the new idm either. last night I messed around with it and one of the times I tried to start to it all it did was crank so I was reading something and still had the key on and I could hear something running it sounded like and as soon as I heard a click I tried again and it fired up and then continued to fire after that and run...I have not yet replaced the pcm relay or diode. the tac moves when it cranks so I don't believe it would be my cam positioner sensor? I didn't notice any smoke while cranking but then again I wasn't watching for it either.
 
#4 ·
I have had the tach move with a bad CPS before. Don't trust just that. They are very inexpensive and you should have a spare in the glove box anyway. Make sure you get one from Ford.

P1670 is a communication error between the PCM and IDM. The CPS codes are P0341 and P0344.

Have you tried running a KOEO (Key On Engine Off) test yet?
 
#5 ·
That's what I was kind of thinking on the sensor there cheap so ill replace that the pcm relay and diode along with it just to rule the small easy things out...I know when I was at the ford garage and they had it hooked up to the computer when I wasn't get my wait to start light he ran a buzz test and whatever other test they could with the computer and at that time we couldn't get anything out of the buzz test and that's when I swapped out the idm and it didn't change anything but my wait to start light has been coming on now....it has always started when my wait to start light would work up to the other night so not sure if this is something new or its all within the prior problem.
 
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