Problem with the, "Check Engine Light" on 1995 Ford F-350

In January of 2010 I had to have the transmission rebuilt. The shop claimed I was pulling too heavy a load (approx. 12,000#). Once the unit was rebuilt and running, the "Check Engine Light" came on and no-one can find the cause. I have had the truck to two different dealers and four independent shops with the same results. "Can't find the reason". Any ideas?

by in Streetman, TX on March 09, 2011
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2 answers 4 comments
ANSWER by , March 09, 2011
what was the code they retrieved?? Roy
COMMENT by , March 09, 2011
Roy, sorry but don't have one. The shops with an old '95 analyzer reported they had no code to try and the dealers tried to use a newer analyzer with no results. Is there any way you could take an educated guess as to the cause? Thanks
COMMENT by , March 09, 2011
very hard to guess with hundreds of codes available. my guess would be o2 sensors as you pull heavy loads and the motor works very hard and the mixture has to go full rich for long periods of time where the ecm cannot compensate quick enough. does the motor run ok?? is the trans ok?? by the way, did they add an external trans cooler for you?? Roy
COMMENT by , March 10, 2011
Roy, I will mention the O2 sensors to the dealer but remember the "CEL" became the problem after I pulled the trailer and had the trans rebuilt. The engine and trans both run great. No additional trans cooling was installed. I have recently pulled my stock trailer and horses weighing about 6,000# without a problem. Perplexing problem, isn't it.
COMMENT by , March 10, 2011
I always install additional cooler when you are pulling the weight your pulling. cant be to safe trying to keep the trans fluid as cool as possible. Roy
ANSWER by , March 10, 2011
You absolutely need (another!) new shop if you can't get a code pulled with an active check engine light. With the OBDI, you can take a jumper wire (or even a paper clip!) and jump the connector to flash out the codes through the check engine light itself! Sure, you need to know certain during the test when to turn the steering wheel and when to give it a wide-open throttle shot. But it's something that should be a no-brainer. Good luck...