E40D Overdrive help

[Titojeep]

Hey guys, looking for input on something that happened today. 1993 F350 CC dually, 212K with Transmission that was rebuilt 15K miles ago.

So far have experienced no problems with this tranny since I aquired the truck at 199K. This morning on the way to work (65mph at 2200rpm) I noticed the rpm kick up to 3000rpm as if it kicked out of OD momentarily. It did it about 4 times on my 52 mile trip. Two weeks ago I pulled a 5000lb camper on a 900 mile round trip vacation trip and no problems. Trans fluid is still pink, no bad smell, or anthing indicating something is or has been going wrong. Any ideas? I'm not sure what the sequence of operation is for the transmission in terms of overdrive operation so I hope it's something simple like a sensor, or something.

Thanks in advance.

 

[oldmisterbill]

I would start by cleaning all ! I mean all the electrical connections.I had the same problem.there are 3 under the master cylinder as well as the ones on the transmission.Dont forget the computor connector.

 

[bike-maker]

I had a 97 with a E40D that did something similar. Finally figured out that if I put enough pressure on the right turn signal switch - not fully engaging it - to turn the signals on while changing lanes going down the freeway, it would momentarily short with the OD button on the shifter. That was a newer truck, but same trans and switches as yours. I would take the switches on the column apart and clean them too.

 

[david85]

Do as suggested and see what you find. Did your speedometer flicker at all when this happened?

 

[OLDBULL8]

Check the brake taillight bulbs, if they short out, thats the same as putting the brakes on which kicks it out of OD.

 

[trackspeeder]

The converter is unlocking. Do the tail light check as in OLDBULLS post.

 

[Highridge]

I've been fighting the same problem too. If you unhook the batteries and reset the computer it will make it stop for a few days I've notcied. I replaced the fipl, vss, and tach sensor and it still does it so I'm going to try cleaning all the connections and maybe the turn signal switch next. Anyone know where the computer for the tranny is located?

 

[icanfixall]

Why yes I do.... Its found under the drivers side floor kick panel behind the psrking brake leg... And boy-o-boy is it ever tuff to reach... The main cab plug can be seen looking down deep into the drivers side fender well behind everything. Its about 6 inches long and 1 inch wide. Held in place by 2 long winded bolts that are tuff as hell to reach. I would just clean the 3 plugs under the master cylinder and the 6 or 7 plugs on the trans. Contact cleaner thats harmless to plastic... Let dry and grease with die electric grease. Hopefully this will fix things.

 

[fury9]

You can also tweak the tps to shift to your liking (make sure you make a baseline marking and adjust in 1/8-1/16" increments) but as for the taillights and such, I doubt that they would cause this problem. But I could be wrong. Do you have a trans temp gage? EDIT: also IIRC,maybe, I think there is either a sensor on the rear end or tailshaft that may have went kaput

 

[Titojeep]

WOW, I love being in the IDI community. Great responses! I had an opportunity at lunch to drive around on the interstate. I literally tried everything to make it do this again and it didn't. On the way home today, same results. Nothing unusual at all. Regardless, I'll definately check everything you all noted above starting with the tranny connectors, however the one thing I did notice on the way home was that the Tach seemed to be operating a little weird. By that I mean, it seemed to jump slightly when I was at a constant throttle position. Not much, just enough for me to notice it if I stared at it.
I'm off for the weekend so I'll have plenty of time to check things out. Thanks again to all who have replied.

 

[david85]

Tachometer and speedometer need to work perfectly for the truck to perform. Look into that tack. Check the wires on the sensor (big 1" nut on the front of the engine), pull the sensor out and clean off the magnetic pickup. Look for any signs of frayed wires and correct as necessary. If it still acts up, you may have to replace the sensor.

 

[international]

The converter is unlocking. Do the tail light check as in OLDBULLS post.

x2

 

[fury9]

well I suppose you could start at the light bulbs but I just don't see how in an older truck it could really adversely affect the trans. But I have heard of the KISS principal and it makes sense to check the taillights. But X2 on the tach sensor, but even cleaning it off may not do any good and that is a dealer part only.Is there some kind of ohm readings for the taillamp sockets and the tach sensor that anybody knows of?

 

[icanfixall]

Fury9.... When the brakes are applied that sends a signal to the trans to unlock the torque converter. If it didn't the truck would stall just like a standard trans if you didn't push in the clutch.... Now if the brake lite filament breaks and touches the turnlite filament every time to turn on that turn signal direction (left or right) the torque converter will unlock. Trust me on this.. When I rebuilt my motor the first time I had this issue. Everytime I used the left turn signal my converter would unlock and lock up. Turns out the rear left turn signal filament was broken in the bulb and touching the brake signal filament. That took plenty of hunting to find too. These E4OD trans have a few funny little quirks. Let off the throttle around 45 mph and the trans goes into coast mode. It feels like its in neutral but it isn't. Now add just the smallest throttle and watch the rpms just back up as the torque converter locks up. These are "things" the stealership wont tell you. It was a money maker for them but now the guys that knew of these things are gone... We fix our own now because of this site. These thing I learned here and will teach others about it too. My charge is free... Bet you can't get anything free at the dealer garage...

 

[fury9]

Maybe they designed it that way just to make money? But thanks for the info and I will pass it on whenever one of you guys don't get the chance to.