Scania Traction Control TC

[renesis]

Hi, I have a Scania P114 6X4 truck equipped with EDC and ABS (Wabco D) with Traction Control (TC).

The truck has to undergo a mandatory vehicle inspection every half yearly, and one of the criteria for passing is the Traction Control (TC) if equipped.
The 2nd axle is driven on the dynamometer and the truck is driven in every gear. According to the inspection criteria, when

1) TC is ON (by default), vehicle speed should not be > 10kmh. This sounds logical as TC prevents the wheels from slipping due to loss of traction.
2) TC is OFF (by a TC Off Road Switch), vehicle speed should be at least 45kmh. During the test, the vehicle speed could only reach 35kmh. Engine output seems to be regulated by the TC feature.

On normal road driving, with either TC ON or OFF, truck can travel up to 70kmh with no problems whatsoever.

My question is this: Is there a speed limit for the ABS/TC feature when TC is turned off? Theoretically, if the truck is stuck in mud/snow/...etc, no body will try to move off from 45kmh which is way too fast anyway in such conditions.

I cant seem to find the configuration anywhere thru Scania Diagnos (SD2). Thanks for any advise.
Best Regards

[jctech]

On the chasis dyno the ABS will see a wheel speed difference between the front axle (0kph) and drive axle (35kph), it will interpret this as either wheel spin or an ABS fault.

[renesis]

Yes JCTech, I understand that.
The TC Off-Road button is supposed to allow the difference in wheel speed on the dyno. That's why on the dyno the tester has to turn off TC.

During the dyno run with TC off, the maximum speed reached on the truck is only 35kmh, whereby the vehicle dyno test requires a speed of at least 45kmh.

So is the limit of 35kmh a predefined value set in the WABCO ABS ecu?

[jctech]

I do not know about the 35KPH setting

[renesis]

I managed to find some Wabco documents, and in it they explained briefly about ABS off-road (or TC in my case).

When in off-road mode, more wheelspin is permitted upto approx 15kmh more than the front wheels, to a maximum of 40kmh. Anything more and the TC engine control will take over. So it is not exactly TC-off, but TC-off-road mode.

Now... how do I explain to the inspector in layman terms?

[jctech]

I managed to find some Wabco documents, and in it they explained briefly about ABS off-road (or TC in my case).

When in off-road mode, more wheelspin is permitted upto approx 15kmh more than the front wheels, to a maximum of 40kmh. Anything more and the TC engine control will take over. So it is not exactly TC-off, but TC-off-road mode.

Now... how do I explain to the inspector in layman terms?

Show him the Wabco document......and hope he understands