Truck is a 1991 F-350 4x4, 7.3 Banks Turbo, e4OD with banks shift kit.
I've been having major transmission issues lately, which I finally fixed by replacing my MLPS (manual link position sensor) and changing the fluid. After this my transmission worked AWESOME, with the exception of a 3-5 second pause before it would engage into Reverse.
So two days ago I decided to tackle the next problem, the truck had no tail lights. It has a utility bed on it, and the lights wouldn't work. After some tinkering around, fixing wires that were grounding out, replacing corroded light bulbs, and splicing a wire under the dash that had been cut in half by the previous owner, all the running lights, reverse lights, turn signals, ad break lights finally worked for the first time since I bought the truck.
Yesterday I drove the truck and noticed the OD switch light was flashing at me. the ATF level was good, and it was driving fine, so I kept driving. On my way home the truck drove fine until I stopped at a stop light. The engine starting working very hard to stay running, and then stalled out when I stopped. I started it and it runs fine in Park or Neutral, but as soon as its engaged in gear the engine fights to stay running and dies again. I revved up the engine and put it in drive, and after a shaky start everything worked fine, until the stop sign by my house, where it died again. I FINALLY got going, but only after lurching to a stop about five times when I restarted the truck and tried the rev engine and engage transmission trick. I barely got into the driveway.
At low speeds the truck feels like I'm trying to drive while standing on the brakes. When I engage the transmission and it stalls out its exactly like coasting to a stop in a manual transmission without putting in the clutch. The transmission is staying "locked up in gear" and killing the engine. BUT, if I put the tranny into neutral, it goes in fine and the engine runs fine. WTF??? Some research on this site tells me that if the brake lights aren't functioning right, the Torque Converter will stay locked up, because the power going to the brake lights is actually connected to the transmission, and it "tells" the torque converter you are coming to a stop....it that right??? That seems absolutely ridiculous, but at the same time makes a heck of a lot of sense in my situation, being that I was working on the brake lights the day before the S.H.T.F.- To make matters worse I'm supposed to be driving the truck up to a ranch this weekend to do a ton of tree work, and have 6 guys depending on it to haul all their tools and gear. Please help me!!!

 

Wow 3-5 seconds to drop in Reverse! I have no idea if that's right or not, but I have heard from E4OD owners, they are slow to drop in Reverse....

E4OD owners, it this acually right? 3-5 seconds to drop in Reverse????


And yes i've read acually a couple times, the transmission also relies on the brake lights to operate correctly and to unlock the TC when brakes are applied.


That's gotta be your problem. But didn't you say you fixed the lights and now they work? Maybe you cut/bypassed a wire that was going to the lights - to the transmission?

 

Your torque converter is staying locked when it shouldn't - there is a clutch inside the converter that act just like the clutch in a manual trans, when it's engaged it removes the converter's internal slip (what allows the engine to idle while transmission is still in gear). The converter lockup clutch is supposed to only engage in 3rd and 4th gear, but it's action is controlled by the PCM through grounding one wire in the transmission harness - I suppose that if said wire's insulation got chaffed and the now bare wire is touching metal somewhere on the frame this would cause the converter to stay locked up all the time, which results in just those off-idle stalls and hoppy-skippy accelerations you're experiencing. Just to clarify, this is not a normal failure management mode in the PCM, because in those situations the PCM would run the converter open all the time, which causes more heat but makes sure nothing actually burns up inside the trans (which is what will happen if you keep driving the truck in the state that it's in right now).

Now, some people are unhappy about the way the PCM controls the converter lockup clutch, so they install a manual switch that allows them to lock and unlock the converter as they please, totally disregarding what the PCM may want to do at the time. I suppose it's possible a PO had that mod done to the truck, and the one wire you connected under the dash is what was used for the switch in the past... Or you may have the physically-damaged wire in the harness like I suggested in the beginning. Either way, start investigating - the wire controlling the converter's clutch is a purple wire with a yellow tracer stripe

 

Yes, it takes forever for the E4OD to go into reverse, nothing uncommon.

On the TCC action, yes the PCM uses the brake lights as an input to unlock the converter, but this implies the converter is already locked up, which only happens in 3rd and OD, reportedly in 2nd sometimes, but absolutely never while the transmission is in 1st gear. This is all PCM-controlled, if there is a harness damage between the PCM and the transmission and the purple/yellow wire is now permanently grounded for whatever reason, there ain't nothing the PCM can do about it.

 

Willysfreak, if you can't figure out where the damage is, you can always do the manual switch mod I mentioned in my first post, and be done with the whole mess - i have that in my truck, and recently did it to another one, the result is fairly fool-proof and depending on how exactly you wire the switch up it can either work with your PCM or put you in total control of the torque converter completely bypassing the PCM... and I got the wiring diagrams to do either

 

Man I came this close || to buying a 1990 Diesel with the E4OD, I would of probably killed it when ever I would use reverse LOL i'm use to my C6's, drive forward, stop, slap it up in R and by the time I take my foot off the brake and back on the skinny pedal, it's already in Reverse!

With the E4OD, I'd be already revving it before it would drop in gear, then it would make it slam hard in Reverse! lol

 

LCAM, Thanks! I'll be tracking down the purple/yellow wire tomorrow and see what I can find. Does the PCM harness start in the dash under the steering column? Or is it in the engine bay? If I CAN"T find the problem with the purple/yellow wire, I'd be happy to rewire my T.C. to go part/full manual, whichever is easier (faster) to do-unfortunatly time is of the essence. If you've got the diagrams on your computer and have time I'll take a copy!
willysfreak55@hotmail.com
THANKS!!!

 

willysfreak, i just done mod on mine a few days ago. it works good. i done mine so on would be factory and off would keep the converter from locking until i wanted it to. now my truck had 2 purple and white wires, so cut the first one i seen...wrong wire, truck would not turn the starter. had to put it back together. the right wire on mine was a little purple stripe with a little white stripe. the wrong wire was a purple wire with a little white stripe. if you need how i done mine let me know, cost me 5 dollars and 30 minutes

 

sorry guys, also mine is a 90 model, dont think the brake lights work my converter unlocking it. unlocks as soon as i take my foot off the gas, and as soon as im back in the throttle it locks back up,

 

guys have to wait for reverse? man that must suck hahaha. sorry!

 

Email sent, along with some explanations - actually I gave you the PDFs that have instructions too, cause most folks fell more comfortable knowing why they're doing what they're doing, instead of just blindly following a wiring diagram And the harness starts from the PCM on the engine-side of the firewall, but it's usually easier to locate its other end where it plugs into the transmission and the just follow it to where you have enough space to dig into it comfortably. Just a heads-up tho, you will need a small resistor and some relays, all can be bought at about any RadioShack store for under $15.

The brake lights do cause the converter to unlock, but you usually don't feel it cause the PCM also does what you described and by the time you move your foot from the throttle to the brake the converter is already unlocked. Try this tho, next time you're on the interstate keep your right foot on the throttle nice and steady, and with the left one lightly tap on the brake pedal, just enough to make the lights come on but without actually building any brake line pressure to slow the truck down - you'll notice the converter unlocking then. And by the way, that exact behavior where the converter unlocks when you let off the throttle is the most common reason for installing the manual switch - you need the converter locked for engine braking, and the E4OD in its factory trim will not allow that, with the switch you can keep the converter locked and thus use engine braking. Or you can wire up the switch to keep the converter unlocked most of the time, like you did. Or you can have it like mine on full-manual lock/unlock, with no input from the PCM at all. Or you can wire it up where you have manual unlock, manual lock, and full-auto where the PCM takes over... All depends on what you like really.

 

Oh yeah, how do you like your 3 forward speeds? I sure do like my six

 

My E4OD never takes longer than 1 second to engage into reverse and forward is quicker. I remember when I first got my truck it felt like engagement with the C6 was taking forever compared to the AOD in my F150. I got uses to it though.

I'd probably blow a gasket if I had to wait longer than 3 seconds.

 

David, but your transmission is not anywhere near stock '90-'91, now, is it?

 

very oddly,my reverse is fast as well.no delay.
yeah but wreck, when she's going forward at 45 + and directly locked,the trans temps drop unlike the always open c6,and the rpms fall out of site too saving some mad $ at the pump.
a few little issues here and there is a small price to pay.


"with banks shift kit"

i wounder if that banks transcommand is giving him his troubles?