So, my new to me 2005 STR with 118k miles just started throwing a P0735 code and a transmission fault light. Turning the car off then back on clears the transmission fault error light. After doing some experiments i determined that the car will throw this error if I am in 6th gear around 2000rpm and gently apply throttle, i hear a strange noise(squawk?) from the trans before it shifts to 5th gear and then the fault light appears. If i mash the throttle l, the noise and error do not appear. I can also manually shift to 5th gear and there is no problem. The local independent jag you are shop checked the fluid level and also reprogrammed the transmission and cleared the adaptation. After the problem happened again they suggested getting a new Mechatronics unit at $3000.

Has anyone experienced this problem? Is there a cheaper way to fix it? Thanks for the help.

 

I don't remember the code off hand, maybe a gear incorrect ratio code, can check tomorrow. As for the squawk noise, there was a bulletin for that, you put in an additive from ZF. You drain a litre of trams fluid, then put the additive in to get rid of the noise. As for the the. Code and warning coming back, it may very well be that you need a new valvebody/TCM unit.....,it's all one piece on the 6 speed ZF trams. If it turns out to be that it will need to be programmed.

 

I think thectsc.com had the mechatronic unit for $1580. I am pretty sure i can install it myself. I am not sure where to get it programmed and i am not sure if installing one of these would actually fix it.

 

Installing it is pretty straight forward, but since the TCM is part of it, it needs to be programmed, preferably by the dealer or someone with SDD. I can look up the code tomorrow and let you know what it says. It might just be a solenoid, but I don't think you can get solenoid a seperately on this model trains. But let me look up the info tomorrow and I'll get back to you.

 

Ok thanks JBz. It does look like i can get individual solenoids here:
Mechatronic Parts: The CTSC - ZF Parts

 

Yep, its the incorrect gear ratio code for 5th gear. Possible causes are J-Gate incorrect adjustment, trans fluid low or mechanical failure. You can try adjusting the J- gate, and checking the trans fluid to rule them out. If they don't solve it, then you are most likely looking at a new Valve Body/TCM assembly.

 

I recently replaced my zf5hp24 valve body and it was not difficult just a little time consuming and I am sure you is about the same. I would recommend that if you drop the pan look it over for metal shavings if you see them know you may have additional trouble down the road. I would also recommend that if you change the trans fluid from the ZF fluid be sure to flush the system to the radiator.

 

So I spent time talking to DOSE BMW in San Diego, they seem to be the ZF experts in the area. Steve Dose believes that my eclutch is bad and that is what is making noise when it trys to shift from 6 to 5th gear. He says that replacing the mechatronic unit will not fix this issue. So I am considering getting a used transmission and swapping it in. Does anyone know if any V8 S type transmission from 2003-2008 will work or do I need an R specific one? Also, I am assuming a 2003 S type R trans is the same as a 2005 S type R trans?

 

The 6 speed trans should be the same. Only thing that might differ from a v6, n/a v8 to s/c v8 is software. Once you swap it, as Gus said, flush the cooler in the radiator. It might need to be programmed, or at least check software level, and a trans adaptation clear. It's possible that Dose is true, I just remember Jaguar had a bulletin for putting in an additive, and this was for a barking/squaking noise on accerleration, and relatively low speed. If you're going to swap the entire trans, make sure the one you're getting that the pan isn't leaking nor the electrical connector sleeve, those you have to drop the pan to change if they've been leaking, plus the pans are prone to warping themselves and leaking. Just something to check for you put it all in. Good luck.

 

Before you get a used transmission call this company Eriksson and get a price of a reconditioned unit. This is where I got my transmission from. It is a transmission done right and it has the fluid in it just plug and play and they are an authorized ZF distributors.

Link Eriksson Industries

 

I just talked to Eriksson, they are a good resource. They confirm what DOSE BMW has told me that it is probably a hard part in the trans that needs to be replaced. I asked if they sell rebuilt units, and they said they don't have cores for the jag 6 speed. I would have to ship them my trans and have them ship it back a week later. Rebuild cost would be $2800 and shipping about $500 each way. So it seems like letting DOSE do everything for me at around $4500-$5000 is not such a bad deal.

 

Yes it is a big job and you will need a transmission lift. I changed mine in about 4hrs but I had help.

 

Opinions wanted

If I have resigned myself to the fact that I will need to completely rebuild the trans for around $4500, can anyone think of a reason not to just drive it as is until the problem gets so bad that I have to rebuild it?

 

You are dammed if you do and dammed if you don�t. The way I look at it is if your trans fails on the road where are you going to take it and how much is it going to cost for towing and how are you going to get home. The best question is are you going to keep the car.