So my transmission was having problems earlier this year and about 3 weeks ago it finally gave up the ghost. Wouldn't move in any gear. I had it towed and trans was rebuilt by a shop that from what I know is quite competent and has done many E4OD's.

When I picked it up everything seemed to run fine although shifts were a tad firm. Fast forward about 10 days it dropped out of gear once while driving then slammed back into it. Then it started holding 1st gear all the way up to 3000 rpm until slamming into 2nd.

Up to this point it only happened once. So I was hoping it was just a hiccup. Unfortunately no. I towed for the first time since the rebuild 2 days ago and the transmission just seemed lost. It was holding 1st too long and for the first 10 miles the overdrive off switch was working keeping it out of O/D. Then suddenly the trans just started over riding the switch and shifting into OD.

The worst part came when i started going up a hill (in 3rd) i gave it more pedal to maintain speed and instead of downshifting, it upshifted onto 4th and locked the TC. I had to manually drop it to 2nd. But once that happened no matter what it would shift as fast as possible into 4th and lock the TC. So i
was trying to tow about 10k at 1200 rpms and it would not downshift no matter how much throttle I gave it. Also trans was not overheating stayed right at 140.

Now as far as what I have done to it. Obviously the rebuild which includes a new billet TC, new shift tube in the steering column and new MLPS.
The TPS is brand new AND properly adjusted.
New VSS, brand new solenoid pack (not reman), i replaced both plugs for the pack and mlps, new tach sensor. I have checked every connection i could find related to the trans and as far as I can tell all the wiring is in good shape.

That being said the only codes i'm getting are trans temp sensor (trans was at 130* when tested) and code 99 EPC solenoid.

Truck is a 94 F350 7.3L IDI cclb 4x4 unkown original miles about 500 mi on the rebuild. Shop will not warranty the electrical due to a whole lot of DIY wiring (although nothing tying into trans that I could tell) which is why i'm seeking any ideas here as the shop will charge me to hunt the problem down.

My only other thought is to replace the pcm since its the only thing not new. Either that or rip the entire wiring harness out of the truck and find a new one somewhere. If you made it this long without falling asleep god bless you and any help is appreciated!

 

FLPS, fuel lever position sensor aka the throttle position sensor is bad I will almost guarantee that. They dont last long anyway and I will just about guarantee the rebuilder did not bother replacing or even adjusting it (1.2 volts at idle and ~4.5 at full throttle) I learned this lesson twice the hard way first with my 94 IDI-T that I replaced the torque converter, solenoid pack, TCU and speed sensor in before I figured out the FLPS was the problem. Then my 91 had its trans rebuilt at least 3 times because of a bad FLPS. As I am sure you already know get a good name brand too, the borg warner that oreillys sells is a motorcraft part in their box. Hope this helps and your old tach sensor was good and I appreciate it much

 

The TPS is only about 2 months old only a couple thousand miles on it. I got the BW one and adjusted it myself. I even checked it just last weekend because I thought maybe it got out of wack when they replaced the transmission. But it's showing 5 volts and is set to 1.2 and 4.1. I moved the throttle lever through the full range of motion several times and couldn't fibd any dead spots so i'm confident my tps is good. But thank you i'm accepting any and all ideas because i'm out of em.

glad the tach sensor worked out for ya

 

Might be on to something here. Looking at the pins ont the Transmission control unit are some supposed to be set deeper than others? I found that if i jam the plug in there real hard the tranny will work fine for a bit. After a while it'll go back to having shift issues. I'm thunking this may be a poor connection here. So i took it apart and found that the pins on the unit are not all the same length, is this right?

 

Not familiar with the IDI TCM myself, but I'm thinking there should be a bolt holding the harness connector onto the TCM connector. Does yours have one?

 

Woops sorry I meant thhe cruise control servo. Was googling about 5 different things at once. The pins are quite solid where they are so i think thats how they are supposed to be.
But is it possible my cruise control is out of whack causing shifting issues? Because every single time I push in the connector for the servo it runs properly for 10-20 min until it acts up again. Maybe its shorting out somewhere? I'm going to pull the fuse for the cruise and see if the symptoms come back.

 

Removing the CC fuse would be a good test. Or see how it drives when you completely disconnect the cc servo connector.

Remind me - would the '94 have a center stop light in the cab roof?

 

Edit - dup - disregard.

 

Yes it does have the high stop lamp. Put brand new bulbs in a couple days ago and verified its working

 

Ok so i left the fuse for the cruise control in and unplugged the servo. Had shift issues as soon as I left my driveway. So i pulled over and pulled the fuse in under hood box labeled horn/speed control. Not sure if this is the right one but i found about four with speed control listed and this seemed to have the least impact on other symptoms. Anyway that cured the shifting symptoms. Made the 10 min drive home with no issues. I'll reserve judgment until i drive it for another hundred or so miles but as of now everything points to the CC as the culprit.