4R100 question - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 2 (permalink) Old 08-30-2012, 07:29 PM Thread Starter
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Join Date: Apr 2012
Posts: 24
4R100 question

Hello all,

Let me start with basic information on the truck here.

2000 model year

F350 crew cab dualie shortbed

7.3 4R100

3.73 rear gears

235/85/16 tires all around


81k miles

I recently purchased this truck a month ago after it had been sitting for 4 years and before I started driving the truck every last fluid was changed including filters as well.

The problem arose last Sunday which was the first time I have driven the truck in the rain. The truck started normally but after driving approximately 200 yards my O/D light started flashing a trouble code and put itself into limp mode. The code was PO755 which was "shift solenoid B". Now the only thing that had changed since it had been on the road was the introduction of condensation. Now on one of my old 7.3 IDI trucks with an E4OD the plug would fill with water and cause a limp mode condition. I would unplug it and blow the connectors out and voila problem solved.

I've personally verified 12.4 volts coming to end of the harness where it plugs into the solenoid pack. The connectors are clean with no breaks. The wires appear to be in good condition with no chaffing or rub through. I found a replacment solenoid pack locally for 235 out the door and have no problems replacing it myself but I'm not wanting to throw parts in that aren't needed.

As I said, the only thing that changed was the fact it was driven in the rain. Truck sat overnight before trip and it occurred right away. It's been hot and dry since and problem is still there. This has me stumped.

Thanks for any help.

P.S. fluid is still clean, not burnt, no metal shaving in pan or anything g like that either. It appears to be electrical only.
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post #2 of 2 (permalink) Old 08-31-2012, 01:02 AM
Former Ford Trans Engr.
Mark Kovalsky's Avatar
Join Date: Aug 2007
Location: SE Florida
Posts: 3,029
Re: 4R100 question

You can check the wiring electrically between the PCM and the transmission. Check for electrical continuity, shorts to ground, and shorts to power. A visual inspection doesn't cut it. You can also use jumpers and a wiring diagram and put 12 volts across each shift solenoid and listen for the click. Do this with the engine off. If it clicks the solenoid and trans internal wiring is fine. It is going to be the wiring or the solenoid. This way you can determine which one.

Former Ford Automatic Transmission Engineer

“The good thing about science is that it's true whether or not you believe in it.” ― Neil deGrasse Tyson
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