Hello all, my 1996 F250 5.8L with an E40D has been having problems for about two weeks. My alternator died and killed the entire truck and since then the transmission hasn’t been shifting right. It revs up super high in first gear then bangs into second instantly stuttering and going limp. I used a code reader and am getting a 622, 624, and 628 code. The most interesting part is these problems are intermittent. The truck will work beautifully for 3 days then go back to having the problems mentioned above. Any ideas help.

 

Interesting codes. The common part between all these codes is the transmission connector on the passenger side of the transmission, above the oil pan. It common for these to get damaged by exhaust heat. They also sometimes leak and become contaminated with transmission fluid. Pull the connector off and check it for damage and wetness. Clean it with contact cleaner before reinstalling it.

 

If the connector is wet with trans fluid inside, I'd replace the harness
Maybe clean it all out once for testing, but that may be futile
I would look / run through the pinpoint tests for both of those codes
Used to see the wires in those harnesses get hard as a rock and add resistance

 

Hello,

I had my mechanic check my 1994 5.0 Auto F150 and he said my shifting problem was due to a connector/harness that is getting transmission fluid in it. He said that they do not work on transmissions and i should take it to a transmission shop. The symptoms are it will drive find for several miles, then all of a sudden it will downshift like i "as if" gave it a lot of gas for passing or something. If I let the truck sit for several days and it will work find changing gear, then after several miles, it starts again. I have a second problem, just to mention is a high idle issue. I start it then it will high idle then drive it about 25 feet to a stop sign. It will idle down like normal, but the moment I will give it gas it will idle high again until I stop again then idle back down.

For the first issue you had posted here is the copy of the post. Whenever I try to explain this, every tranny shop keep saying rebuild transmission even after I try to explain about the connector harness thing. Does anyone knows what the name of the connector and where it is located on the transmission? Can you even get a replacement part (harness)?

Bernard

 

Most transmission shops are looking for low hanging fruit
Replacing the trans harness is not hard and they have no way of warrantying their work
What if the truck exhibits the exact same symptoms?
That is why
I think it may fix your isue
But I have not personally checked it over with my scan tool and brain
The harness is not too hard for a trans shop or the dealer
I have replaced a few
You can learn on this one
Are you handy?
Do it yourself?

 

I chased varying trans codes like the OP for years. They came & went along with in/out limp mode.

When it began to slip at differing speeds, I pulled it & had it rebuilt by a well respected shop.

Still had problems.

Had leaking capacitors in computer & a flakey PSOM (lives on back of your electronic speedometer).

Replaced caps in ECU & sourced a PSOM from a junkyard.

Problems gone.

I strongly recommend checking out the ECU before committing to any major repair of the trans.

 

Agreed
Hoops to jump through to verify a few things

 

Thank you both. I will start with the ECU then see about getting the wiring harness replaced. Can you explain how to locate and replace the transmission wiring harness?

 

There is no replacing a harness. It's all one piece & no replacements exists except for a junkyard.

Repair only. No new computers either. Only repaired ones. Sorry.