TCS problem

[Seanny]

Hi everyone,
I have an issue with my TCS. 2009 CC 115,000km, serviced on time, runs well, no crashes - a nice car.

The issue is that the TCS activates under certain conditions - at about 55-65 kmph, turning right on curves when the steering wheel is at 45 degrees. Steering feels vague and loose as if tie rod end do not exist, ABS starts to activate, can power out of it, but do need to turn off TCS. It is worst on curves that go left and right pretty quickly. TCS light may flash when pushed hard. Only turning right, not left, drives normally.

Drives as expected when not on curvy roads, worst when going up hill. Roads where I live are smooth, in good condition and it has not rained in Brisbane. Does not throw a code, Vagcom has not detected anything, ABS sensors have been cleaned, steering components looked over, battery is good, no visble loose wires. I am running out of options.

Is it posible to change out the TCS module, say with a module from wreckers? Where is the module located? Is it an easy thing to do? Could the steering rack be damaged in any way? Is the TCS linked to something else in terms of computer modules?

This baffling and my independent mechanic may not have all the ideas.

Any help or questions are greatly appreciated.

Cheers, Seanny

[kamold]

Traction control is part of the ABS module. If it's not throwing any faults seems unlikely to be an issue with that module, but if you want to rule it out, I may have a suitable ABS sitting in the garage you can use. In perfect working order, was just swapped out of my car for the B7 ABS which I needed for my adaptive cruise retrofit.
Would just need to pay for shipping from Sydney.
What is the part number and software version of your current ABS?

[Seanny]

Hello Kamold,

Thank you for such a kind offer, this is a positive start. I shall have to look at vehicle tonight to find out some more. You will need to forgive my lack of technical knowledge on the Passat CC, however, I do have advanced skills with 80 Series Land Cruisers.

Are you able to provide part number and software version of the unit that you have removed so that I have some sort of reference to start with?

Thanks and regards,

Seanny

[kamold]

Hi Seanny,
My original ABS module is 3C0614109P running sw 11.
If you don't have diagnostics software to easily interrogate it to tell you what it is, feel free to send me your VIN via PM and I can look it up.

[sambb]

This might seem way out of left field but does relate to what you are experiencing. I have a Polo 9N3 Gti which I track and recently I had a custom recode of the ME7.5 to account for performance mods. As part of that I asked if the person who did the tune could modify the action of the traction control system. In my car when you press the 'ESP' button (which really should be called the traction control button as ESP is always active in the background) and the button is lit, you will see the slippery when wet symbol come up on the dash and TCS is de activated. Left in the default unlit position the TCS is active. What I had changed, was when the TCS is default/active, the brake modulation that takes place below 50kph or so if you loose traction through throttle induced wheelsping is still functional but the throttle cut has been written out of the code. The throttle cut was very aggressive in my car. I had it removed so that I could do TCS aided brake modulated launches at hillclimbs especially in the wet, but without the throttle cut being able to interfere. After the launch I just reach forward and switch the TCS off for the rest of the run and let the LSD do its thing. The person who wrote the code did warn me that it was quite possible that in the absence of the throttle cut that the TCS system might become more aggressive on the brake modulation side of things to get the desired result. I did a lot of launch testing and didnt find this to be so but over time have noticed some strange ESP-like behaviour, exactly like you describe. If my ESP button (lets just call it the TCS) is depressed/traction control off/ slippery when wet symbol permanently lit on the dash, I do not experience it. But with the TCS active in its default turn key position there is one particular sweeping third gear bend where I can feel brake modulation happening. It is a sweeping right hand 3rd gear bend that at a spirited pace you would take at 60-70kph. I experience it though when I am carrying a small amount of throttle but virtually lift and coasting around the corner. It is smooth, there is nothing to upset the car, it is an on camber turn slightly downhill so the car is not picking up an inside wheel, yet with that same 45 degree amount of steering lock nearly every time I go through there the ESP dash light will flash and I can feel brake pulsing happening. It does feel to me like its the inside front which if it is the TCS system would seem as though it thinks its loosing traction on that wheel.
This only started happening after I had the TCS system modified. Now I'm not fussed by this at all. The car has a limited slip diff and I'm not reliant on TCS to keep it from wheelspinning and as I mentioned I only take advantage of the mod for certain types of tracking. I suspect that the mods to the TCS system have in fact caused this weird spin off symptom. To my mind it cant be the ESP system doing it because ESP in my car is always active whether you have activated TCS or not. The only way to turn it off is unplug the brake pedal switch or pull the ESP fuse. It is only when TCS is active that it happens, yet its strange that it is not wheelsping conditions that make it appear, but a single right hand bend nearly rolling around the corner in complete control.
I assume your ECU's aren't modified which makes me think that possible it could be on the output side of the TCS system that you have a problem ie in my case the throttle closure is inactive and as the tuner said he thought it looked like the TCS might try to overcompensate the brake modulation to pick up the shortfall. Picture my scenario where there is wheelspin. The TCS will grab brakes and cut throttle but if the wheelsping continues it'll continue to hold the throttle shut and grab the brakes harder. Still seeing wheelspin and the throttle cut not working because its been deactivated it really starts to grab the brakes until car speed gets above the threshold where brake modulation in the TCS system is not used anymore. If you had a fault in your throttle body perhaps and the ECU wasn't seeing the throttle position feedback it was expecting when TCS is active or a concurrent slowing a wheel that it thinks is spinning then it could be doing the same to you as I'm getting - over eager brake modulation? But why that would happen at times when the wheel speed sensors aren't seeing differentials and TCS shouldn't even be kicked into action, is a bit beyond me.
By all means an ESP module swap would be the first thing I would do too and it sounds like you've thought about the input side already eg steering angle sensor, brake pedal sensor, wheel speed sensors etc . I'd get it out in the wet and deliberately get it to loose traction ina staright line under power to see if the throttle cut is definitely working. You can also left foot brake it with the throttle already down to generate throttle cut too. If you can verify that the two main outputs of the TCS system are in fact working then you can perhaps narrow in on whats happening. Even pulling the fuse to the ESP could be a lead. The ABS is still active when you do that (it is in my car) but ESP isn't so if its not happening after that you can be a little more confident that its the ESP side of things. If it is though, with ESP and TCS out of the equatio then it may be an ABS issue.
anyway good luck. just thought I'd share what I had experienced since it was uncannily the same as yours but due to different deliberate reasons, but there may be some clues in that.