ESOF Transfer Case and Manual Transmission

[kawamatt2]

Does anyone have any information on the availability from Ford of the ESOF (electric shift) transfer case ever coming behind a manual transmission? I ask because I am in process of swapping my E4OD transmission for a manual transmission and would like to keep my electric shift transfer case. Currently (due to lack of knowledge) I am simply jumping the connection between the R/W and BLK wire of the transmission harness to "fool" the ESOF module into thinking the MLPS (manual lever position sensor) is always either in park or neutral. I am thinking though that there should be a better way to do this using the clutch pedal. Essentially what happens with an automatic and MLPS, is that the R/W input to the ESOF module is grounded when the transmission is in park or neutral. The goal here is to ensure that there is no possible power transfer between the engine and transmission during shift to 4LOW. The clutch pedal in a manual transmission equipped truck serves this same purpose.



I recently stumbled on a TSB that Steve83 has posted on his site relating to the ESOF module. This TSB is rife with mentions of a clutch pedal input to the ESOF module in the case of a manual transmission equipped truck. What I can't figure out though is how the clutch pedal input could get to the ESOF module. More over, was there actually ever an application from Ford that had a manual transmission and electric shift transfer case paired.

Any help is appreciated.

[Steve83]

There is no indication in the '92-96 EVTMs that ESOF was available with stickshift, but you're right that it's a simple logical input that should be easy to provide thru the CPP. Have you studied the logic table in the caption of this diagram?



It's relevant to note that, when the starter is NOT engaged, the R/LB circuit to the relay becomes a weak ground (through the relay's coil winding). So anything connected to that circuit (even through some of the CPP's other terminals) receives a ground input. But you need to investigate what happens to the ESOF module if it receives 12V on that "ground" input since that would happen during cranking.

If that doesn't appear to be workable, another way to deal with it is to realize that the function of that input is simply to inhibit the RANGE button. So if you can wire the the CPP to interfere with that circuit (O/LB), you'll accomplish the same thing.

[kawamatt2]

Originally Posted by Steve83

Have you studied the logic table in the caption of this diagram?

Yes! Heavily in fact. You might remember a thread some 6 months or so ago where I gave some input and asked some questions about the color coding and logic of this switch. What I never could figure out though was how to use two of the pins to trigger a ground. Pins 1 & 2 I had thought were open circuit until the key was turned to run and engergized the starter relay with 12 volts. Pins 3 & 4 are that weird "weak ground" circuit through the BOO and the tail lights and cruise module. I had no confidence I could piggy back off this circuit to get a ground (or a hot lead to trigger a relay ground) without affecting cruise control. Pins 5 & 6 I thought were the same setup as 1 & 2, only get a signal during engine cranking.

Originally Posted by Steve83

It's relevant to note that, when the starter is NOT engaged, the R/LB circuit to the relay becomes a weak ground (through the relay's coil winding). So anything connected to that circuit (even through some of the CPP's other terminals) receives a ground input. But you need to investigate what happens to the ESOF module if it receives 12V on that "ground" input since that would happen during cranking.

This I did not understand until now. Basically the R/LB wire is connected to one side of the relay coil and the other side of the coil is grounded. So when there is no current being pushed on R/LB from ignition switch, you would see ground? Interesting. I do worry though what would be the effect of pushing 12 volts to the ESOF module that is expecting a ground. I don't necessarily want to fry it.

Originally Posted by Steve83

If that doesn't appear to be workable, another way to deal with it is to realize that the function of that input is simply to inhibit the RANGE button. So if you can wire the the CPP to interfere with that circuit (O/LB), you'll accomplish the same thing.

You've confused me here. You're saying that the purpose of grounding the R/W is to stop the shift. So, i could keep the jumpered R/W-BK as I have shown and then somehome use the CPP to break the circuit of the O/LB wire from the ESOF to the transfer case motor? Would this not "confuse" the ESOF when it tries to send a signal to the motor but the position sensor does not see the motor move?

In any event, after studing on the logic of the ESOF and what allows a shift, I'm not so worried about actually wiring in a manual switch for the "neutral safety" as it appears that the ESOF also solicits input from the speed sensor to determine if a shift is possible. So I couldn't theoretically being rolling along in 4HI and hit the 4LOW button and a shift occur. This due to the speed sensor telling the ESOF the truck is still moving. I would have to be stopped, and being stopped in a manual transmission truck is mutually exclusive with either the clutch depressed, transmission in neutral, or engine off.

Thanks!

[Steve83]

Originally Posted by kawamatt2

You might remember a thread some 6 months or so ago...

Nada chance, unless you had POSTED ALL THIS IN THAT THREAD.

Originally Posted by kawamatt2

Pins 1 & 2 I had thought were open circuit until the key was turned...

The key position has NO effect on the CPP switch output; the CPP is only affected by the Clutch Pedal Position, obviously.

Originally Posted by kawamatt2

So when there is no current..., you would see ground?

Yes, but ALSO when there is significantly LESS current than it takes to operate the start relay, which is ~4A. So that circuit can pass >0.4A, and the voltage won't rise significantly. It depends on how the ESOF is programmed &/or built to detect ground as to exactly how much current the circuit could pass (voltage at the ESOF pin) and still qualify as a "ground" input to the ESOF.

Originally Posted by kawamatt2

You're saying that the purpose of grounding the R/W is to stop the shift.

No; it's to tell the ESOF not to attempt the shift. Not to actually interfere with a shift that's already happening.

Originally Posted by kawamatt2

the circuit of the O/LB wire from the ESOF to the transfer case motor?

Take a closer look at the circuit: O/LB doesn't go to the motor. Then re-read what I posted before. What I'm saying is, you MIGHT be able to wire the CPP to interrupt the RANGE button, so the ESOF never even tries to make a range shift if the clutch is engaged (pedal released).

Originally Posted by kawamatt2

...it appears that the ESOF also solicits input from the speed sensor to determine if a shift is possible.

I don't remember ever reading anything like that, but it's been a while since I've read that TSB - I don't have ESOF, so I've never really needed to.

Originally Posted by kawamatt2

...being stopped in a manual transmission truck is mutually exclusive with either the clutch depressed, transmission in neutral, or engine off.

"Mutually exclusive" means any one of them excludes the possibility of any other. I think you meant something like "analagous" or "equivalent".

[adrianspeeder]

First case I've seen a stick with ESOF was in a '95 ranger, but from my order guide collection, you couldn't get it in Bronco's or F-150s. Even in the '97 body style dad was forced to order a manual transfer case with the M5OD. The superduties were the first big trucks I've found with a stick and ESOF.

Adrianspeeder