Traction Control Fault / Fail

[vitesse]

Can you move the cog wheel manually ie large flat bladed screwdriver in the slots (carefully)? If not it has jammed and needs replacing.


Regards

[Matt G]

Hi Vitesse.

Thanks for the response and apologies for slow reply, been working all weekend , no it doesn’t move, but I haven’t wanted to force it too much. So on that basis, it’s a high chance it’s the actuator that’s failed, I was expecting more towards 12v when I tested with the old voltmeter.

I’ll try the actuator first

Thanks in advance

Matt

[SD1too]

Originally Posted by Matt G

I have picked up exactly the same the issue on my ZT, I am reading 10.6v at the connector ...

Hello Matt,

This 3 year old thread is interesting and mention of traction control and cruise control components prompted me to read all about it in RAVE.

Firstly just to clarify that these two systems don't share any control equipment.

• The cruise control uses an ECU controlled vacuum pump and a pneumatic actuator which operate on the primary throttle butterfly attached to the accelerator pedal.
• The traction control uses the ABS modulator and the secondary throttle actuator (referred to above, with gear teeth and a cable) which is electrically driven by the traction control ECU.

The voltage used for the traction control actuator is not specified so I don't think you should assume that 10.6v necessarily represents a fault or that it would be expected to move when the engine is started. I doubt very much that this would be the case as it would close the secondary throttle which would oppose the action of the idle air control valve.

There's a chart to help with basic diagnosis:

• Does your Traction Control warning remain illuminated after the 4 seconds bulb check when the ignition is switched on?
• Has the Traction Control button accidentally been pressed to turn the system off?
• Do you have a continuous brake and/or ABS warning light illuminated as well?

Simon

[stocktake]

From first hand experience, my traction control unit on my KV6 auto (which is identical to the unit that is used on the cruise control on the early BMW E39) performs a self test when ign is turned on.

This involves the traction control unit completely closing the second butterfly in the throttle assy and then returning to its rest open position, if it cannot complete this action ( due to among other things broken or jammed teeth on the drive) then the traction control sign is displayed on the IPK

[Matt G]

Thanks both for the reply.

Absolutely agreed, the earlier post related to cruise control in places, but my issue is very much traction control only.

The fault light comes in during the 4 sec testing stage, am I right to think it should close and open during this test?

The fault light stays on permanently there after, have tried the on/off button too

I do not have any other warning lights for abs, etc, so I was assuming it not to be the pump or wheel sensor on that basis.

As suggested by vitesse I’ve tried a screwdriver in the cog and it does not budge. I’ve managed to locate a cheap enough E39 actuator, so will update the page once it arrives, as this has been quite an informative post.

Thanks in advance

Matt

[stocktake]

It's the early E39 actuator and then it may have a different electrical plug but usually they are the same, the later ones are totally different, you can tell by looking at them the difference is so obvious, also the cable will need swapping (easy peasy). And yes the cog should move during self test ( it is quite a heavy old cog to move to he honest dont be shy)

[vitesse]

Originally Posted by stocktake

It's the early E39 actuator and then it may the later ones are totally different)

I've come across the same actuator but with a different shaped connector but even the other shaped connector ones can be used. While the plastic connector is different the pins are in the same place and with a bit of butchery, (or the other BMW connector spliced in) can be put into service - I've got one on my 75.

Keep well

ps Poor photo but believe this may be the kind with the other connector: https://www.ebay.co.uk/itm/173969930...4AAOSwxGBdMcIn

[SD1too]

Originally Posted by Matt G

The fault light comes in during the 4 sec testing stage, am I right to think it should close and open during this test?

Hello Matt,

I've just tried Stocktake's test on my KV6 auto (of the same age as his). With my right hand resting on the traction control actuator and my left switching on the ignition, I can feel and hear the two distinctive operations which Dave explains as the secondary throttle butterfly closing and opening again.

So yes, yours should do this and the traction control warning should not appear in the message centre.

I hope this helps.

Simon