I have a F-250 diesel with a E-40D transmission. The transmission/torque converter has 100K miles on it. As I am cruising, (even at high speeds) it appears the torque converter is unlocking/locking. The difference in RPM is the same as when it locks up. Any suggestions as to troubleshoot?

 

Check for codes in the computer. Check that all three brake lights are working correctly. If one or more isn't right it can cause this to happen.

 

Thanks Mark. I will give it a shot.

 

After that,if the issue isn't resolved,try this:

E40D: The Importance Of A Clean Trans Harness.

 

Took it to a trans shop to read codes. Nothing! They say that year does not "hold" codes so it has to be failing at time of check to see code. I guess I will have to bring it in and have them put the pressure gages on it.
The plug on the tranny was recently changed (less than a year).

 

I forgot to report the light on the shifter never has "blinked" through all of this. Trans guy told me to try driving out of overdrive and see if symtoms are still there.

 

Transmission shop is stupid. The ECU does store codes. Go to your nearest parts house and buy one of the cheap code readers for old Fords. Read the included instructions to retrieve the codes yourself.

 

Don't go back there. They either are stupid or lying. It's impossible to say which one.

 

When you cancel OD does the light illuminate? I ask because I'm surprised that it's not flashing and your at least not getting code 62.It should only take like 5 times of the TECA seeing the converter unlocking when it shouldn't, to set the code and make the light flash (associated with late and firm shifts)......Then of course you hope to get another code to go with it,like code 23 (while holding WOT with the key off during scan) to help you know you've got a dead spot in your TPS or something.This is just an example only.Don't throw darts at it though.Go grab an obd1 ford code scanner.
Example:


Most any auto store has them in stock.Oddly,since they're pretty dated now.
Oh and your port isn't under the dash like modern vehicles.It's out under the hood over by the power distribution box/drivers side hood hinge.Mark shows how to read the codes with a volt meter too if you search his threads for the link.Someone posted a video doing that once and though it's free it's sure not as easy as a code scanner that beeps and flashes clearly.I had a little difficult time helping him count the swings in the meter.For 20-30 bucks just go grab the scanner.Good to have for all IDI/E4OD owners.

 

OK I finally got to the bottom of this. I have rubber hoses connecting the trans cooler to the trans. I have steel lines to the front of the engine and then rubber hose clamped over them. One of the lines was leaking and apparently sucking air just enough to cause problems. I replaced lines and all is well.


Update: Everything fine on 1K trip. Now here lately, no tach, shifter flashing, trans hard shift. After driving several miles, tach starts to work and all is well again. Sounds like new tach sensor time. Where exactly is that located? Do they sell at local parts store?


Thank you all for helping with this.


Ford Forum. The best

 

OK, I found the tach sensor. I measured resistance. It shows open. Where is best place to get one. I see $68 on Ebay. Kind of pricey.

 

Yeah it's a ford item only.They are a bit pricey.If you search the IDI section you find where folks used a different sensor and modified it to work.IMO,it's probably not worth it.If I had a manual trans truck I may try it as it's just to make a gauge read.With the E4OD the trans relies on this info being accurate.It may be just fine too with a modified sensor,I don't know.I would just place your order and buy the ford part.Ford sensors though a bit more pricey,seem to be better than other sensors anyway and will likely last another 20 plus years.

 

Well..I've been driving it about a month now with the new tachometer sending unit. All is well. Whew! Dodged the bullet that time. Thought I was in for a tranny rebuild.
Thank you all for your help. I really appreciate it. I want to drive my "baby" till the wheels fall off.
Tom