Thread: Traction Control versus Cruise Control Question:

Originally Posted by sierrafery

Describe what happened maybe it has some logic... there is the so called VSS(vehicle speed signal)a digital signal which is used by both CC and TC systems and it's generated by the SLABS ECU calculated based on all 4 ABS sensor inputs, there are cases when this signal has a momentary failure which would cancel the CC and affect the TC operation too... usually you'll find a "road speed missing" fault code logged in the engine ECU if it's that.

This has not happened to me. I am just curious. I think that the TC will not activate at speed, I find it hard to think of to be in a situation, driving at speed to cause the traction control to kick in. Something happens that at 100 kph one wheel slip so much that the traction control kicks in is going to be a very bad situation any way.

Originally Posted by Bohica

This has not happened to me. I am just curious. I think that the TC will not activate at speed, I find it hard to think of to be in a situation, driving at speed to cause the traction control to kick in. Something happens that at 100 kph one wheel slip so much that the traction control kicks in is going to be a very bad situation any way.

I vaguely remember traction control kicking in,on occasions, at speed on dirt roads with bad corrugations.

That is at speeds over 80 km/hr.

Only happened in the D2,never seen it happen in the D4.

Originally Posted by Pedro_The_Swift

Do people actually operate cruise control anywhere other than a highway???
how on earth does TC cut in at 100kph?
The two systems should never "meet" surely,,,

I would love it if my CC would work at a speed that let me crawl over rocks etc. My old G60 Patrol had a hand throttle. So did all the Military LRs I worked with and on. It is brilliant when the going is rough and a bit bouncy, and your foot is likely to bob up and down on the loud pedal. Cruise would be amazing in that situation.

Often I used to use the CC control on the Scania to hold revs to build up air over the trailers. Maybe something similar is poss on LRs. Not likely, I know, but my point is that CC isn't only for 100 Km/h on the freeway,

You can indeed...but the threshold is massively higher.
tures down to the wear bars it doesn't take much water on the road to get planing...

I've seen TC operate briefly on the highway in heavy rain in the Defender.

The systems are inter link and Tc will turn CC off . As tc will need to pull back engine power and possibly add braking to wheels .

IMO according to the system's descriptions the CC is disabled by a brake switch input which is not the case when TC kicks in, if it does and affects the vehicle speed normally the CC should work to keep the speed steady like when you meet a hill with CC on not to be disabled

CC will also drop if there is a sudden change in speed, up or down and an event that would activate TC at speed would also cause a jump in the speed reading therefore drop CC.