I've spent a few days searching threads for a problem like mine before posting this. Hoping to just fix the truck and move on. This has me a bit stumped and all the thread reading hasn't helped. I'll summarize the condition and what I've done so far. I've made every effort to not introduce new variables.
​​​​​​165k milesCurrent condition:
Transmission only has forward gears when shifted manually. When shifting manually all the way until 4th gear the transmission operates just as it should. It up shifts and downshifts on the highway no problem. You can go from slow speeds around 20 mph up to highway speeds at 75 and 80. Zero issues. Once you come to very slow speeds or full stop it seems to shift into neutral. Does not move forward. If you put the gear selector back into first and manually shift through the gears no problem.

No flashing M/S lights. They do come on and cycle through the diagnostics with the ignition on then when it started they go off.
​​​​​​
Fluid condition/level: Good/Full. No debris or burnt smell
Gear shift indicator on dash functioning as normal
Battery voltage: 13.8-14.1 while running.
All grounds checked/cleaned
Speedo is functioning as normal
No ABS or CEL Codes.
Current Trans Faults as found by the Hawkeye: P0705, P0722.
I see there has been a shoddy linkage repair done before me. It makes me wonder if there's something wrong with the XYZ switch. But all of my reading says that if there was a problem the M&S lights would be flashing.



So I have one electrical code and one for slippage of the TC. Two separate problems? Could one be causing the other? I have no problem changing the transmission or having it rebuilt I just need to know that I'm not throwing money at it for no reason. Despite me getting a Mechanical code I want to be sure it's not something electrical. It seems to me the trans is having an issue knowing what gear it's in. Which sounds electrical to me.

 

I wish I had better input for you. I just thought I'd suggest that maybe changing your screen name would fix it.

In all seriousness, have you done any live data checks? I'm not sure what that would tell you with a Hawkeye but maybe you could get some insight on that the electronics *think* are happening as you shift through the gears. The systems do sound XYZ related but I agree on the M&S lights. They always flash whenever I've come upon a confused gear selection situation.

I can send you an 03 TCU if you want to try that. It may be worth disconnecting and reconnecting the one you've got too.

 

That repair would be suspect to me - looks like there is all kinds of play or binding possible.

 

It looks like it replaced the plastic clip that should be there. Question is why...new XYZ switch? Or trans repair? Or did it simply fall off. Believe it or not it's solid. Nothing moving or wiggling. Obviously gonna fix it right but it's solid enough to make me look past it for now.

Ahab, do they require a sync or reset of any kind of you swap them out?

 

take a look at this thread.

i had the same issue with my '01.


from one of the responses i received, "A common problem with all ZF 4HP22/24 boxes is the failure of the oneway ‘sprag’ clutch. Once the cams in this one way sprag clutch ‘flip‘ the unit will slip both ways resulting in the vehicle only pulling off with the shifter in position ‘1’ not ‘D’ and driving OK when shifted up to position 2,3 and D until you stop then you need to pull it back to ‘1’ to start off again."

 

No, I don't think the TCU syncs with anything but I'm definitely not the authority on that. Just from what I've read in the technical docs. I'm willing to bet that jastutte has correctly identified the problem though. The offer still stands if you're interested however.

 

Crap. I think you're right.

 

It's an internal clutch inside the transmission. That hose clamp is taking the place of the metal clip but it really just keeps the cable itself from falling down out of the mount.