2007 V8 4.6 Transmission Shift Major Malfunction, Wrench, Traction Control Indicator On and c | Ford Explorer Forums - Serious Explorations

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2007 V8 4.6 Transmission Shift Major Malfunction, Wrench, Traction Control Indicator On and c


October 29, 2009
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City, State
Shakopee, MN
Year, Model & Trim Level
2007 EB 4x4 V8
Reporting on an ugly situation with a happy ending.

One cold morning after my truck was sitting outside all week (0 degrees F) after warm up I was driving about 45 to 50 MPH in heavy traffic. All of a sudden Ol' Blue had a huge mis-shift, hard enough to describe as being hit from the rear. I noticed the speedometer jump up from 45 to 50 MPH then the wrench came on and so did the traction control indicator. Also I was limited to 3rd gear all the way home, which I have read is to protect the transmission. Turned the truck off and back on and the lights disappeared. Next day I took it into Advanced Auto for a code read which displayed U1900 ABS Control Area Network Communication Bus Malfunction!

Came home sort of upset thinking I guess I need a new transmission. Perhaps the control module or other within the transmission was faulty. Could come up with nothing however, I found a glimpse of a probable cause. Came across another 2006 stock explorer form post with the U1900 + an ignition fault code. I didn't have the ignition fault but at 135K miles I figured it was a good place to start replacing parts.

Ford Communication U-codes Caused by Faulty Ignition System

Replaced all 8 coils with OEM motor craft and I have logged 1,000 miles in similar conditions and no fault. Interestingly overall the truck shifts smoother overall through all gears plus I have a better throttle response. A few months back I had my 2nd transmission dump, filter and re-fill at 132K miles as I was suspicious that it could be shifting better, especially around 45 MPH. The transmission service didn't really improve anything nor was it a huge concern, back of mind thing. Now with the new coils it's like brand new operation. Ol' Blue is back!

The hypothesis here is that faulty coils can cause an electrical communication fault on the trans/control network bus. I do know that the main wiring harness for the trans/control system runs right on top of the passenger coils. Go figure. This is a < $400 easy dyi fix versus a possible $5K new transmission.

Coils messing up transmissions shifts? If that is true I may want to change my coils! I have a thread here that is related to a P0375 code I am trying to learn about, but your experience with the jumping rpm around 40 mph and trouble light sounds familiar to me as it was a condition that preceded what i have now. I've got 168K on the 2008 V8 Explorer.
easy enough to replace coils and it is probably over due anyway. Thanks for posting and let me know if you ever ran into a P0375 which is apparently related to a fifth gear ratio issue. See my other post.

Happy to report that 60k later still no issues with my transmission. The new coils took care of that U1900 error.