hillpc

I installed a new F125 switch, and the PRND432 display reads all the gears correctly now as I move the gear selector cable (disconnected from the gear selector lever) by hand from inside the cabin, or as I move the transmission lever that the cable connects to on the side of the trans.

(By the way, changing out the F125 switch is really a bear to do without removing the interfering exhaust pipe - see instructions at audipages A8 F125 Transmission Switch Replacement. To me it seems that one really needs to have experienced-mechanic-type finger muscle control to spin bolts in that very tight area when removing and re-installing the trans mount bracket, the top bolt in particular. It would have been much easier to remove the section of exhaust that's in the way but mine had so much rust on it that I knew I'd tear up the exhaust if I tried to remove it.)

Until I tried to drive the car in D. When I stepped on the gas, all the PRND432 lit up again, and car started moving in (I assume) 3rd gear, just like before. I drove it a half mile, stopped, pulled the cable from inside the car into R to make a U-turn. Pushed the cable end into 2 to drive back home. Still felt the same (assuming 3rd gear). When I got back into the garage, I couldn't budge the cable out of 2; it was stuck tight. (I think I cracked the plastic ring at the gear selector end of the cable the last time I tried to put the car into P after a short drive - at that time the selector was still attached to the plastic ring at the inside end of the cable, and that puts a lot more force on the cable than I could by hand without the mechanical advantage of the gear selector.)

This morning I could easily pull the cable into P or any other position, and the display reads correctly again.

Seems to me that something is jamming in the valve body when it warms up. (Why would the cable jam?) I haven't tried to check the fluid level yet, but suspect I should pull the valve body next. I haven't had the pan off the car yet.

nossisnave

Ooops hillpc I admit I was thinking of the switch at the front of the transmission and thought that was the F125. That's my mistake, sorry to be confusing

I had the code for incorrect gear ratio as well but mine had to warm up before it began slipping out of gear and eventually going into Limp mode. Makes me think yours is actually an electrical issue. I've got the number to ZF America lying around somewhere if you wanted to call and pick somebody's brain about why it's going into Limp immediately. The trans techs were very helpful when I was having issues

hillpc

Wow, they would give advice?

nossisnave

Yeah, they did for me. I've called and chatted in need of assistance on several different occasions, for my previous '01 A6 and now with the LWB. They were always very helpful.

I just asked to pick his brain and told him exactly the symptoms and he was correct about how big an issue it was. I was hoping for an electrical problem or incorrect type of fluid and he said it could be either of those but felt it was more serious and would require rebuilding the transmission, and he was right: I had to pull it and replace an O-ring inside one of the clutch baskets.

They know their stuff. I can pm you with the number and ext if you'd like.

hillpc

Can't hurt. Thanks.

hillpc

Today I pulled the 17mm allen fill plug and got 1.7 liters out (cold). I thought nothing was supposed to come out there, especially when cold. Then I pulled the drain plug, the pan, and the filter. Got another 5.1 liters out. The fluid looked somewhat dirty, but didn't smell burnt at all, and did not have any metal pieces in it or in the pan. A few black specks. -

update - Car wasn't running when I got 1.7 liters out of the fill hole. Just saw that maybe the under/overfilled determination could be in error if the car isn't running.

So now I'm wondering if I should change the filter and add new fluid to the correct level and try again, or if this will be an exercise in futility, and I should pull the valve body and start hunting around there, because of the gear selector cable jamming after the trans is warmed up.

I have codes but neglected to clear them after the replacing F125 switch, so I don't know which of them are old and which ones are still current. The battery also went dead and was disconnected for replacement, so I don't know which of the codes might be from this.

5 Faults Found:
18258 - Powertrain Data Bus
P1850 - 35-10 - Missing Message from ECU - Intermittent
18157 - Transmission Control Unit Incorrectly Coded
P1749 - 35-10 - - Intermittent
17114 - Gear Ratio Monitoring
P0730 - 35-00 - Incorrect Gear Ratio
17090 - Transmission Range Sensor (F125)
P0706 - 35-10 - Implausible Signal - Intermittent
17087 - Brake Switch (F)
P0703 - 35-00 - Electrical Malfunction

The Bentley does say that a "possible cause of fault" for code 17114/P0730 "incorrect gear ratio" is "ATF-level not OK or ATF contaminated". The other 2 possible causes listed are "sender for transmission output RPM - G195- faulty", and "Clutch slipping/faulty or solenoid valve dirty/faulty". I have no codes relating to the G195 or any solenoids.

Based on this, I'm leaning towards putting it back together with a new filter and gasket and driving it around the block again after clearing the codes. I guess the worst case is that if I have to rebuild it, I'll have bought a filter and gasket already, which I assume will also come with the rebuild kit.

Or do you think I should just pull the valve body now and start poking around? Maybe I should look at that part that's moved by the gear selector cable and seems to jam up. I have not been able to find the ZF valve body manual 5HPVBMAN on the internet.

nossisnave

Yeah I think the car always has to be running to properly check the fluid level, but after the car gets to a certain temperature it needs to be shut down and allowed to cool.

If the pan is still off I would try to find out what is binding up the gear selector. It's pretty odd tho that it went away after the car had sat overnight, I hate issues that aren't consistent. Then go at the fluid level/fluid change. That will also allow starting and verifying that the codes you are getting are in fact current to the problem.

I'll be at my garage today and will have that number and extension for you, sorry about the delay. I've also got a 5HP24A spare parts catalog but I'm not sure what good it would do you. You're welcome to it tho

hillpc

I pulled the valve body and see that the (looks like plastic) sliding valve of some sort that's moved by the gear selector moves very easily in the valve body, on the bench, cold. I have to disassemble some more in order to get it out to look at it. Other parts that are (eventually) driven by the gear selector (and could therefore be jamming it) are the detent mechanism for the ranges, and a rod going across from the lever (which has the ball for the cable on it) hooked up to the parking lock mechanism (for P). The parking lock mechanism has some slop in it at one location, but some faint recollection from years ago (non-Audi) makes me think that may be normal. I'll have to investigate.

To be sure it's not the cable (though why would the cable seize up after warming; exhaust heat?), I should really disconnect it from the ball on the lever at the trans, and see if the same jamming symptoms persist at the ball. I think I'll have to drive it around with the cable on (so I can shift to P, R, D while driving for the warmup) and then put it on the lift and disconnect the cable from the ball and try to move the ball/lever by hand, if I can get in there without burning my hand on the exhaust.

Thanks.

hillpc

Lots of posts on the Jaguar forums about this common crack in the (rear upper?, near the solenoids) valve body section. Pic attached. I read that one guy claimed no big deal if it doesn't penetrate into fluid passages. (Do I feel lucky?) Another said that the common pressure regulator valve problem causes this as well as causing the common catastrophic breakage of the A-drum (which is now offered in a stronger version).

So now I'm leaning towards getting a replacement valve body part (any suggestions from where?; there seem to be a lot of variants) and also doing the pressure regulator fix with reaming and bigger valve; less than $50, if I can risk doing the reaming freehand without a jig) and trying again. I can't see anything obviously wrong with the plastic manual valve or its bore when I removed it. (There seems very little slop between it and its bore.) Then doing a rebuild if I have to. A rebuilt valve body complete is over $1300 at the one place I checked so far, and I'm not sure they'd give me a core charge back because of the crack.

I don't want this job to spiral out of control cost-wise so I'm thinking a bit at a time as I find stuff wrong. (But it's tying up my lift.) A reman from Rock Auto is over 5 grand, with a grand core charge. Maybe just put it back together with new fluid and filter and see what the VAGCOM reads after clearing the codes and resolving the jammed shift cable?

tozoM8

They are not interchangeable.