Hello people,

I was wondering if anyone could help me please. I am currently in the process of installing an Om602 with a 722.6 (I believe taken from an e300td) into my 1981 ford f250.

Engine and trans are in and now I'm just trying to make everything work! I'm at the stage of ytring to install the gear shifter, the only problem I'm having is that i can't get the gear selector arm on the trans to shift from park!

Am pretty sure the trans was working fine before. I had someone service it before it went in. Also I have a spare trans and the spare was moving fine through the gears and now is also stuck in park! Some research has told me that the Pawl is whats's doing it and that some torque applied to the trans output shaft will at the same time pushing on the gear selector arm should free it but this doesn't seem to work (on either transmission). Some more research has suggested that once the propshaft is installed - I don't have it yet, it's still being made), then by pushing the van forwards and backwards a little should provide enough torque to free the pawl, but honestly i don't see how this could be the case every time i put the truck in park.

I then started thinking that there must be some sort of solenoid or electrical signal required to free the trans but chatgpt is adamant that the722.6 should be purely mechanical (when not connected to the shifter assembly, and the the shifter assembly itself is what has the solenoid in?).

I have an OleGear aftermarket controller to manage the trans.

Anyway i sure could use some help with this if any of you good people would be able to illuminate me some!

Also on a last note, I have heard that the 722.6 is quite particular about how the shifter works with it and that it can throw itself into 'limp mode' if alignment is slightly off. if anyone has some advice on how to get it right first time that would also be greatly appreciated!

Thank you in advance,

Andoni

It is the shift lever that locks, not the transmission pawl.
The stock Electronic Shifter Module (ESM) has an electrically operated catch that locks the shift lever in Park unless power is on and it receives the signal from the brake lamp switch; at that time the lock is released.
The shift lever position module located in the ESM uses opto-couplers to determine shift lever position (PRND) and transmits that info via CANBus to the TCM (at least '00 and later do so; some earlier versions may not have the CANBus). It is this position module that can cause a erroneous shift lever position versus transmission conductor plate comparison.
If everything is lined up, with the ESM in P and the transmission in P, everything should line up mechanically.
I just can't understand the parking pawl refusing to release; it shouldn't take that much pressure to lift it up. Unless you have the drivetrain fully installed and the vehicle parked on a steep slope, the pawl should release relatively easily.
I'm looking at the "parking linkage exploded view" in the ATSG 722.6 transmission manual and I see no electrical or mechanical operated lock mechanism. If you don't have a copy of the ATSG manual, you should purchase one.

hey,

thank you so much for getting back to me.
so just to check i'm understanding this right the ESM with the electrically operated catch will still be in operation even if the transmission is currently not connected to anything? . (that's to say, its bolted to the engine but is not wired up at all). - when i said it went through the gears before i was referring to when being moved with the selector arm on the side of the trans.

So if I start wiring in the gear shifter, when it receives the brake light input it should release.?

Thanks again mate.
really appreciate it.

Correct about the ESM in operation so long as the electrical is connected; it doesn't even have to be in the car. It does, however, have to be mechanically connected to the transmission selector arm to do you any good. The transmission itself, connected electrically or not, should allow the transmission selector arm to be actuated by hand. Again, there is no interlock internal to the transmission to lock the selector arm in place; any locking is performed at the ESM. The transmission just drops the parking pawl lever onto the parking pawl whenever the selector arm is moved to the Park position.

The catch is a small solenoid operated piece. It can be removed or even wired to a circuit that goes "hot" whenever the key is on; this does remove the safety interlock that prevents one from starting the car in gear (I experienced that only one time in my life in a mid-60's Cadillac before safety interlocks were in common use. Quite the experience to start the car and it just takes off because I failed to ensure the transmission was in Park!).

The below link will give you an idea of the ESM; I had to replace the gear position module in mine. There should be a way to mechanically release the catch using a pen or screwdriver on the ESM; the position of the access port/panel depends upon the ESM model. Youtube shows several examples of which (of course) none apply to either of my E55s...
https://mbworld.org/forums/w211-amg/...5-19-32-a.html

You will need schematics to know which connection activates the solenoid which means knowing the year/model from which the ESM came. You can find schematics for the donor car at "charm.li". They have the WIS files for most Mercedes models of interest to enthusiast today.

A couple of items that may assist you. The first I believe applies to the earlier 722.6; the later versions used the opto-coupler position sensors located in the ESM.


Item #43 is what raises and lowers item #49 to engage when shift lever is in Park.

thanks so much for all the wisdom bbirdwell.
maybe its just that my pawl is hard stuck?. i will try adding some ATF. gearbox is currently dry and then hoping that lubricates things better and then having another go.