PCM dead?
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From: Algona, Iowa
PCM dead?
Hello everyone my name is Sid. I have a 1997 F-250 HD 7.5 and E4OD. About a year ago the trans started acting up by trying to shift into OD at 25 MPH. This wouldn't happen every time kind of random thing. I thought i had narrowed it down to the solenoid pack so i replaced it and everything was good for about a week. The same thing started to happen again but i noticed it only occurred on very humid or rainy days. i don't put many miles on the truck so i just dealt with it. Well about a month ago i noticed after the first run through the gears it shifted perfect until the truck was shut off. After restarting once through the gears it was fine. I got the bright idea of unhooking the battery to clear any codes and to see if this changed anything. It did and now it tries to hit OD at 25 MPH every time. When i pull the codes i get 633 (4WD in low) and 622 (shift solenoid 2 fault). After inspecting and testing the 4wd switch and entire trans harness i still get both codes. I have pulled pin 12 (4wd low) out of the PCM connector cleared codes and still get 633 & 622. This leads me to believe the PCM is faulty. Does this sound logical? What else should i do before getting a different PCM?
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From: Algona, Iowa
I did some more investigating today i found that that the only time pin 12 (4WD low wire) isn't grounded is when the key is off and the transfer case is in 2WD. With the key on it's grounded all the time even with the transfer case switch unplugged. I also pulled the pcm out and looked it over. I can see that some moisture had seeped in around the rubber that holds it in but it wasn't wet, no burnt smell and no visual damage. Does anyone have a schematic of the 4WD low wire circut? (black w blue stripe)
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I have the same truck and exact same issues. My E4OD would shift fine and then hesitate to shift, Rev high and shift hard. Then it would stop, at first l thought shift solinoid or an accumulater. I actually ordered a new pcm because l wasn't getting any codes to pull up and I had a couple other issues. That didn't help, l read someone else had the issue and changed out their TPS so l did and sure enough that fixed it.
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From: Algona, Iowa
Glad to hear you figured it out!
My hunt continues as I replaced the transfer case indicator switch with no results. The 4WD low wire is still grounded with the key on and the transfer case in any position. I would assume the only time it should be grounded is when the case is in low. I plan on stopping at the local dealer and see if they can provide a schematic for the 4WD low wire.
My hunt continues as I replaced the transfer case indicator switch with no results. The 4WD low wire is still grounded with the key on and the transfer case in any position. I would assume the only time it should be grounded is when the case is in low. I plan on stopping at the local dealer and see if they can provide a schematic for the 4WD low wire.
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From: Algona, Iowa
I found a wiring schematic for the 4wd low wire and figured out it goes from the pcm plug into the dash indicator light. Would it be easier to run a new wire into the light rather then dissecting the main harness? In one of me previous posts I mentioned I had pulled pin 12 out of pcm connector and still had code 633 after clearing the codes by removing the jumper wire during the koeo test. I drove for several miles stopping and starting with no change. By removing the wire shouldn't that eliminate code 633? Any help would be greatly appreciated.
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1987 - 1996 F150 & Larger F-Series Trucks
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Apr 11, 2014 06:38 AM
