PCM/IDM expert advice needed - BADLY!!!
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Posting Guru
Joined: Oct 2011
Posts: 1,647
Likes: 1
From: Exton, PA
Oh, I def had a few last night after it fired up! Prob a few more tonight if I get her moving.
...ok, whether she moves or not.
And yeah, the thing with the contacts is that it was still hard to pull the relay out by hand so I guess I just assumed they were all good. Turns out 2 were good and 2 were bad.
It's also strange that this (apparently) happened to the harnesses of both of my trucks. I wonder if all that current flow to the IDM over the years relaxes they spring properties of the metal clips enough to allow them to open up somewhat?
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
That is really odd, since whatever it was, apparently happened to both of your harnesses. Hopefully that is actually what was causing the issue for you, and not just a coincidence. At any rate, here's to a running truck! 
Hotshot
Joined: Jan 2012
Posts: 11,132
Likes: 3
From: Southern West Virginia
So the crazy thing is that I didn't do much yesterday to make it run. We went about testing the voltages and resistances at the relay itself. To do this I made up 4 test wires with spade ends for the box and slot ends for the relay. Plugged it all in with the relay dangling out of the box, turned the key on and NO CLICKING. Well, just the one click that it should have.
After a bit of head scratching we realized that two of the four contacts in the box were quite loose on the test wire spades.
So, we pulled it out, I pinched the contacts in the box closed more, but the relay back in and it started up. Hopefully that was it. The IC plumbing and fenders are going on today, then she goes for a drive
After a bit of head scratching we realized that two of the four contacts in the box were quite loose on the test wire spades.
So, we pulled it out, I pinched the contacts in the box closed more, but the relay back in and it started up. Hopefully that was it. The IC plumbing and fenders are going on today, then she goes for a drive
Good for you buddy! Glad to hear that is running!
New User
Joined: Jan 2020
Posts: 1
Likes: 0
Did you have a U0105 code
So the crazy thing is that I didn't do much yesterday to make it run. We went about testing the voltages and resistances at the relay itself. To do this I made up 4 test wires with spade ends for the box and slot ends for the relay. Plugged it all in with the relay dangling out of the box, turned the key on and NO CLICKING. Well, just the one click that it should have.
After a bit of head scratching we realized that two of the four contacts in the box were quite loose on the test wire spades.
So, we pulled it out, I pinched the contacts in the box closed more, but the relay back in and it started up. Hopefully that was it. The IC plumbing and fenders are going on today, then she goes for a
drive
After a bit of head scratching we realized that two of the four contacts in the box were quite loose on the test wire spades.
So, we pulled it out, I pinched the contacts in the box closed more, but the relay back in and it started up. Hopefully that was it. The IC plumbing and fenders are going on today, then she goes for a
drive
So did u have a CAN communication problem between the ficm n the pcm ???
Tuned
Joined: Apr 2018
Posts: 324
Likes: 14
Hi, this is an old thread so you might not get answers to it. Double check what I'm telling you, 'cause I didn't. CAN bus doesn't get called that until 2003 with the 6.0. Same with the FICM. These old 7.3 Powerstrokes are barely, but not officially, OBDII. One protocol, SAE j1850 PWM. I don't remember seeing any name or specification for the bus between the PCM and IDM. We can get codes and live data with a compatible OBDII adapter. Most of them are not compatible.
I didn't read the whole thread yet but it sounds like he had some spread connectors on a relay. That would likely be a power circuit. Sometimes people spread those connectors with a probe for a meter.
I didn't read the whole thread yet but it sounds like he had some spread connectors on a relay. That would likely be a power circuit. Sometimes people spread those connectors with a probe for a meter.
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