DSC on and DSC off , what happens

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Jun 13, 2015 | 07:39 AM

jagtoes

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From: NY

DSC on and DSC off , what happens

Just a question to get a little more understanding about traction (DSC). I understand that with it on the brakes are active based on wheel slippage but what other systems are altered. Also other then risking the back end from stepping out are there any neg/positive effects of driving with it on or off. I turned mine off yesterday for the 1st time and did not get any indication of the cars drive-ability and handling. Now granted I did not punch it and do any donuts but it didn't seem to make any difference. I'm assuming with it off the XK would make a good drifter.

Jun 13, 2015 | 09:24 AM

Ngarara

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From: London, UK

The 5.0 manual says:

Quote:

The ABS provides the following brake functions that are designed to assist the vehicle or aid the driver:

ABS.
DSC, including TracDSC.
CBC (corner brake control).
EBD (electronic brake force distribution).
ETC (electronic traction control).
EBA (emergency brake assist).
EDC (engine drag-torque control).
Understeer control.
Electronic brake prefill (vehicles with ASC only).

Elsewhere it says:

Quote:

DSC uses brakes and powertrain torque control to assist in maintaining the yaw stability of the vehicle

The 4.2 manual has less detail, but I think it's fundamentally the same. Just to complete the picture:

CBC reduces braking force on the inside wheels when cornering, to reduce the tendency of the car to tighten into the corner
EBD reduces braking force at the rear to prevent locking due to forward weight transfer
EBA maximises brake pressure when you hit the pedal hard
EDC increases engine torque to avoid rear-wheel lockups due to sudden power off or a manual downshift
Understeer control reduces engine torque and brakes individual wheels to keep the car turning (not sure how this really differs from DSC)
Electronic brake prefill slightly pressures the brake system when you come off the throttle rapidly, on the assumption that you're about to brake

Digging around a bit further, I think that CBC, EBD, EBA & EDC are always on. I'm not sure about Understeer control, because its description sounds a lot like DSC - perhaps it's permanently on for safety reasons.

When you switch to TracDSC, the parameter map for ETC and DSC is changed, allowing the rear wheels to spin more and the car to become more tail-happy, but still allowing the electronics to kick in before things get too out-of-hand. Switch off DSC, and you have no traction control and no oversteer control - if you stomp on the gas & turn the wheel, you can do donuts. I'm pretty sure the other systems stay on.