Newbie S8 ZF Help please

[Tomson]

Good Morning All,

My name is Tom and I own and run a German Car Specialist in Cheltenham called German Marques. As a car/bike enthusiast from birth, 5 years ago I gave up my job and decided to start my company, it was basically a great way to get owning all the cars i've wanted past the wife.

Anyway I've always wanted a D2 S8 and finally in Jan managed to pick one up, although I am now wondering if its a case of never meeting you heroes as the car is causing some issues!

I know the car has been discussed on the forum, it was the 02 plate (possibly a final edition, although not full red leather) that was on eBay with the shifting issues. The car itself was all there and just needed some love, a perfect car for me to use for a year or so before selling on - I could pick bits and bobs off as, and when I had the time.

Anyway, as mentioned in the ad the box was shagged so started to investigate my options, replacement, refurbishment or second hand unit.

Anyway to cut a long story short I ended up buying the smashed S8 from eBay with the recon box. It seemed like a perfect solution as it also came with the TCU.

However, and there is always a however, the smashed S8 was a pre-facelift.

So my guys changed over the boxes which produced the following codes.

18156 - Transmission Control Unit
17090 - Transmission range sensor

So i went to grab the TCU out of the smashed car and it bloody wasn't there !!

The guys who had taken the brakes, dash and engine prior to me buying the car had also taken the TCU.

Thinking caps on we decided it would work if we changed over the valve control block. Sadly the valve control block in the original car had a crack in it (possibly the cause of the gearbox issues with the original car) so we could not do that.

So last night the guys changed over the solenoids from the boxes, it seemed to work, oil back in, bolted it back together, same codes again.

So I really needs some advice please.

the only thing that we have not changed over is the wiring harness and a couple of the other sensors - will this make a difference?

did the valve control block change through the various regions of the ZF5HP-24, and if so even if we change over all of the wiring would it work?

Would sourcing the correct TCU for the pre-facelift box work, could I then recode it to the facelift ECU and Sport shift?

Surely if we change over all of the wiring the box should at least talk to the TCU as its all the original wiring from the facelift car?

Can the original valve control block be welded?

We are keen to tray and get the gearbox out of the smashed S8 to work as it is in excellent condition and has definitely already been refurbished.

Honestly, by the time I add up the hours spent on the box, I should have just had the original box refurbished.

As you can tell I really don't know what to try next.

Any help is much appreciated.


BTW I have been googling this for the last week or so and not arrived with a decent conclusion

[Tomson]

Apologies forgot to mention the gearbox codes.

pre facelift (good box) is DYM
Facelift (with crack in valve block) is ZBG

Also have found out valve control block replacement part is 01L 927 362.

TCU/TCM for DYM is 4D0 927 156 BK

[HPsauce]

Hi, that sounds like a fun job.
Have you contacted our sponsors re a TCU?

You may well have other problems as the donor car will possibly also have a different shifter without Sports mode and corresponding TCU functions.
And the engine ECU will also need to know about all that too - not sure if that's codeable.

As you presumably know a gearbox rebuild of the original isn't going to be cheap......

[Tomson]

Yes I'm heading down the route that the original will have to be rebuilt.

I just can't understand why after changing the solenoids nothing worked.

Does anyone know if when the valve body with changed anything was changed on the casing. I wondered if I could source a new valve body or get the valve body repiaired and then bolt it up to the refurbished DYM?

[HPsauce]

Guy (Daviesbike on here) may be able to advise - he works on those gearboxes and blocks.

[Tomson]

Cheers

[ainarssems]

I now it's too late know but you really should replace like for like with correct code not mix and match. I think ZBG might be typing error as I cannot see such gearbox code. Fault code 18156 just says that control unit is defective and needs to be replaced, 17090 is for F125 switch, it could be switch, wiring or control unit issue. I do not have any details about pinouts but they could be different between different transmission control units. Also engine uses different generations of ECU between PF and FL, I think it was Motronic 5 for PF and Motronic 7 for FL so it's possible that TCU and ECU will not communicate correctly.

[Tomson]

Apologies FBG...

Cheers,

Tom

[Tomson]

So I found this information



on this thread...

http://forum.a8parts.co.uk/showthread.php?t=7323&page=2

I am still trying to decipher it, but am wondering if I have the valve block repaired, or source another valve block (Part Number 1058 427 068) could I bolt this to the DYM?

Interestingly the chart show the valve block part code as 327, not 427 as on my cracked block

[Adrian E]

ZF in the UK are quite helpful - might be worth a call to understand what parts are interchangeable?

Personally I suspect this is going to cause more headaches than anything else and biting the bullet and getting the original box refurbished will be the easiest option.

You're on SRS as well aren't you? There's a chap who has rebuilt an RS6 box and was looking for someone to test it. Won't be right for your S8 I suspect due to gearing, unless you are VERY lucky, but he might be prepared to take yours on as a next project since you clearly have the labour resource available to do the box swap without too much issue?