BAC Forum
General Boards => General Discussion => Topic started by: David T. Richelderfer on February 09, 2013, 04:31:48 AM
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I have a switch on the dash, left side, labeled ATC. There are five switches in a horizontal line under the Kenwood. The right switch is labeled ATC. The next switch to its left is the generator start. I searched on the Forum a few weeks ago for "ATC" and had settled on it being the Automatic Traction Control. But the switch doesn't stay in an "on" position. It simply rocks up when pressed and when released goes back under spring tension to its resting position.
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The ATC is meant to be momentary only. It should not be on full time. When you are starting out on a slick surface, you hold the button down until you get rolling. You already have ATC active in your ABS Electronic Control Unit, and don't have to do anything for your coach to use it as needed.
Normally, the switch should stay inactive, and the ECU automatically compensates if it senses a drive wheel slipping. Pressing the switch can optimize traction by increasing torque to a slipping wheel if needed, and I've used it in the past only when just starting out from a very icy pavement. Using the switch otherwise can damage the drive train should the wheels suddenly gain traction while spinning at high speed.
Joel
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After having done some reading on ATC systems - "A traction control system (TCS), also known as anti-slip regulation (ASR), is typically (but not necessarily) a secondary function of the anti-lock braking system (ABS) on production motor vehicles, designed to prevent loss of traction of driven road wheels. When invoked it therefore enhances driver control as throttle input applied is mis-matched to road surface conditions (due to varying factors) being unable to manage applied torque."
The ATC system works just like the ABS system, only in reverse, and it uses the same wheel-speed sensors the ABS system uses. The ABS system, as we all know, does not allow the BRAKING system to stop wheel rotation while traveling at any speed... which would cause a skidding situaton. The ATC system works to not allow the "ACCELERATION system" (read: your heavy foot) to mismatch wheel rotation speeds... as compared between all the wheels connected to the engine and transmission. The ABS wheel-speed sensors are enlisted by both systems, and both systems work to keep the several wheels turning at near the same speed. The ATC manipulates wheel-spinning speeds by applying braking to those wheels over-spinning, or in more sophisticated systems, by changing torque delivery to individual wheels through the drive train.
ATC and ABS systems are normally on... unless manually turned off or malfunctioning. Soooooo... the ATC switch on my dash is there to manually turn off the ATC system momentarily, and only while I hold the switch into its OFF position... because when I release the switch, it reverts under spring tension to its ON position. If a driver keeps a light foot on the accelerator while starting out on a slippery road, then the ATC system will probably never be required to be turned OFF manually.
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David,
The switch to turn off the ATC system is installed to allow wheel spin for the purpose of rocking the vehicle back and forth to free it when stuck in mud or snow. Since it is almost impossible rock a heavy coach back and forth enough to free it when you are stuck, it is a feature that is very seldom, if ever used.
Gerald