That’s disappointing. It should report solenoid current, in Amps, with a minimum value around 0.05A and a maximum of 0.85A



Phil

Yeah after digging and checking for what ever reason I'm unable to pull any voltage from those solenoids through the GAP tool. I will include my adaptation values below, they are still slowly changing but that's normal I guess.

A - 125 kPa
B - 163 kPa
C - 113 kPa
D - 287 kPa
E - 585 kPa

I assume those charge pressure units are actually mbar, and not kPa, as otherwise they’re a factor of 10 out. If they are in mbar then, predictably, only the E-clutch is outside the recommended limit (+/- 300mbar). I say predictably because of the known issue with rear stator bush wear.

I saw a 6HP28 Mechatronic unit from a 5.0 litre Range Rover going cheap on eBay so I’ve bought it, just for fun, so that I can trace out the hydraulic circuits and determine exactly what the differences are with the 6HP26 unit. It’s a real shame that your IIDTool isn’t playing ball with the solenoid currents.

So the GAP tool is saying this is kPa, and its worth noting, this is after the 2nd unit that was rebuilt

I suspect that the IIDTool is incorrectly displaying kPa as the unit, but it is displaying the correct value (in mbar).

Sorry, I’d forgotten that your transmission has just been rebuilt with new bushes, so maybe the adaptions are still settling down. It would be interesting to see how the values change as you add some miles.

Does the IIDTool only give the charge pressure for the solenoid adaptions, and not the charge time too?

Yeah, at this point I've done about 3,000 miles on the unit with half the driving in downtown Chicago and half the driving on highways for long trip. I can track shift time but they seem off/not correct.

Clutch A - 0.001 s
Clutch B - 6.55 s
Clutch C - 6.55 s
Clutch D - 0 s
Clutch E - 0.0014 s

I know in the past the Gap tool has said my clutch A is at some crazy number for adaptation fill pressures.

Yes, unfortunately people have reported in the past that the IIDTool just doesn't seem to be able to report the solenoid adaptions correctly :

https://www.fullfatrr.com/forum/post551680.html

Phil

Not sure if this helps.
I purchased my truck and started having some mis shifts etc.
I changed the oil and filter and cleared my adaptive values. I used the gap tool in graph mode to track the shifts. Not actually knowing what I was doing or what they meant other than certain ones should be on and others off. It did appear to me that the numbers did not correspond to the letters (eg sol 1 being sol a etc.) as expected according what should be on/off in the manual. Unfortunately I never did take the time to correlate what i was seeing with the manual.
Is it possible that the values are adapting slightly as the clutches wear in?

I have found with my gap tool that sometimes it does not show values correctly. It seems to be less of an issue if the tool is plugged in with the truck off and then started before initializing the blue tooth connection. Has anyone else noticed this?

Does anybody have or know where to find a diagram for the upper half of the valve body. I have the zf6hp28 transmission. I’m putting in the sonnax zip kit and thought I had checked and double checked the location of all the check valves and balls. I missed one and now have to figure out where it goes. Any help much appreciated. I took pictures but they didn’t capture enough detail.

Hoot
2012 HSE Lux 5.0 NA

Here you go

Click image to enlarge

Phil…thank you very much. You just saved my Sunday afternoon. I was prepared to go on a deep dive on the internet. Your diagram confirmed a spot I had marked as a possibility from my pictures but I wasn’t going to put it back together without better information. Thank you sir.

Hoot

RRPhil wrote:

I saw a 6HP28 Mechatronic unit from a 5.0 litre Range Rover going cheap on eBay so I’ve bought it, just for fun, so that I can trace out the hydraulic circuits and determine exactly what the differences are with the 6HP26 unit.

Phil

Having now gone through the 6HP28 Mechatronic unit in some detail, it’s clear that it is completely different to the 6HP26 unit. The solenoids are numbered in the same order :



but activate different clutches :

Click image to enlarge

I’ve reproduced ZF’s logic table for the 6HP26 :



for the 6HP28 :



What concerns me is that there’s no recognition of this difference in the Workshop Manual, where information for the Mechatronic unit from the 6HP26 is simply copied and pasted as a job lot to the 6HP28.

The main difference between the two transmissions (i.e. Generation 1 vs Generation 2) is the much faster response times and shift dynamics (50% improvement) that came about directly as a result of these Mechatronic changes. Hopefully the diagnostic tools get it right when they’re reporting on the status of the solenoids for the 5.0 litre L322 models?

Phil

I've asked GAP before and they are saying that they are just pulling what ever is being communicated from the computers. From my perspective, I don't think many of the value are correct for the zf6hp28. I've spoken with a decent amount of builder and their perspective is given the amount of work and the fact that the trans was rebuilt twice and has a rebuilt valve body too now. I've been told to just drive it and not worry then. Not saying that idea thrills me but its not too bad, its honestly at times just 20-50 rpm max and its very intermittent.

Yeah at this point I'm at a loss.

I've the unit has been replaced twice now and at this point the only original aspect of the trans is the casing and the clutch drums. I've also replaced the trans cooler with a new OEM stock one, replaced coils, plugs, injectors, pcv and valve cover. Still is doing the 2-3 flare. I've spoke with the builder, their opinion is that given that they have told me to not put in more money and that they would rather just extend the warranty and go from there.

I've gotten to a point where I am about to just buy a reconditioned ZF unit from ZF and going from there.