VDC off, but slip light blinks

Pharmacist · 09-29-2009, 01:41 PM

Ok after digging through the user manual, I found some info that may explain a few things, though also raising more questions than it answers.

On page 2-14, it states that the slip indicator light activates when either the VDC (which I assume is mainly concerned with preventing over/understeer) or the traction control (which I assume is mainly about reducing wheelspin during hard acceleration) is activated. It says the light is activated to warn the driver that the vehicle is near its traction limits. On the same page, it says the VDC off light comes on when the VDC off button is pushed, which switches off both VDC AND traction control.

Now on to page 5-27. It talks about VDC using brakes and reducing engine power to keep the car on the steered path i.e. prevent over/understeer. It states that the VDC also uses active brake limited slip (ABLS) to improve traction. It says the ABLS applies brakes to one of the driven wheels if it spins too fast on a slippery surface in order to divert power to the other wheel. This sounds a lot like the traction control system mentioned previously on page 2-14. However, the words "traction control" are never explicitly stated in this section. To make things worse, the manual seems to contradict itself. It further states on page 5-27 that even if the VDC is turned off, the ABLS system remains operational, and if it is activated it will cause the slip indicator light to blink. Note that this contradicts what was mentioned in page 2-14, that the vdc off button turns off both the VDC and traction control. However, it does seem consistent with what I experienced during my drive, with the slip light blinking even though I didn't feel any braking effort on the rear wheels.

Is this an error in the manual, or are traction control and abls different things?

Modshack · 09-29-2009, 01:45 PM

Quote:

Originally Posted by Pharmacist

Is this an error in the manual, or are traction control and abls different things?

They are somewhat different. They use the same hardware though in different ways..

Pharmacist · 09-29-2009, 01:49 PM

Quote:

Originally Posted by Modshack

They are somewhat different. They use the same hardware though in different ways..

Care to elaborate?

Modshack · 09-29-2009, 01:57 PM

Quote:

Originally Posted by Pharmacist

Care to elaborate?

Well...as you get to a brake lock-up situation, the ABS sensors detect this and release the brakes to keep the wheel rolling and maximize braking traction. (this happens very rapidly and is felt in the brake peddle as a pulsation)

Traction control is kinda the opposite...When wheelspin is detected the sensors determine this and the brakes are cycled on rather than off to accomplish essentially the same thing (traction)

Pharmacist · 09-29-2009, 02:12 PM

Quote:

Originally Posted by Modshack

Well...as you get to a brake lock-up situation, the ABS sensors detect this and release the brakes to keep the wheel rolling and maximize braking traction. (this happens very rapidly and is felt in the brake peddle as a pulsation)

Traction control is kinda the opposite...When wheelspin is detected the sensors determine this and the brakes are cycled on rather than off to accomplish essentially the same thing (traction)

No no no no no. What you are talking about is ABS (antilock braking system). That is what prevents wheel locking during hard braking on slippery surface. What I meant was ABLS (active brake limited slip) which operates by braking the faster spinning wheel during hard acceleration. Pretty much the same as traction control and electronic limited slip differential and all the other names its given by different car manufacturers. It's described in detail in page 5-27. Which is exactly the cause of confusion since the manual says traction control is turned off with the vdc button in one section but in another section it says abls stays on even if vdc is off.

Yes, I do know that traction control/abls/electronic lsd/etc..... is nothing more than a software program added to the already existing ABS software and hardware. And that's why a sure way to totally kill off traction control in any car is pulling out the abs fuse.

Modshack · 09-29-2009, 02:30 PM

Quote:

Originally Posted by Pharmacist

No no no no no. What I meant was ABLS (active brake limited slip) which operates by braking the faster spinning wheel during hard acceleration. .

That's pretty much what I said. You can call it by any acronym you want.

To test, go out on a dirt lot, turn of VDC and do a clutch dump. That should answer the question.....Report back..

chief_Roka · 09-29-2009, 09:31 PM

Quote:

Originally Posted by Pharmacist

No no no no no. What you are talking about is ABS (antilock braking system). That is what prevents wheel locking during hard braking on slippery surface. What I meant was ABLS (active brake limited slip) which operates by braking the faster spinning wheel during hard acceleration. Pretty much the same as traction control and electronic limited slip differential and all the other names its given by different car manufacturers. It's described in detail in page 5-27. Which is exactly the cause of confusion since the manual says traction control is turned off with the vdc button in one section but in another section it says abls stays on even if vdc is off.

Yes, I do know that traction control/abls/electronic lsd/etc..... is nothing more than a software program added to the already existing ABS software and hardware. And that's why a sure way to totally kill off traction control in any car is pulling out the abs fuse.

Pharmacist... correct me if I'm wrong? But are you saying that VDC can be turned off fully.
And when u turn off VDC you also turn off TCS.... But, TCS never fully shuts off?
So if the 370 feels too much slip? It will automatically reactivate TCS?

G37Sam · 09-29-2009, 09:37 PM

Quote:

Originally Posted by chief_Roka

Pharmacist... correct me if I'm wrong? But are you saying that VDC can be turned off fully.
And when u turn off VDC you also turn off TCS.... But, TCS never fully shuts off?
So if the 370 feels too much slip? It will automatically reactivate TCS?

Yes, the ABS can be turned off fully, however, AT's still won't be able to brake-launch because they need to find a way to prevent fuel cut. I tried it on my G37. Took out the fuse but still couldn't get the damn thing to brake-launch at 3k rpm or do a burn out on a dry surface.

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09-29-2009, 01:41 PM	#1 (permalink)
Pharmacist A True Z Fanatic Join Date: May 2009 Location: Toronto, Ontario Posts: 1,249 Drives: 09 370z Sport 6MT Rep Power: 20	Ok after digging through the user manual, I found some info that may explain a few things, though also raising more questions than it answers. On page 2-14, it states that the slip indicator light activates when either the VDC (which I assume is mainly concerned with preventing over/understeer) or the traction control (which I assume is mainly about reducing wheelspin during hard acceleration) is activated. It says the light is activated to warn the driver that the vehicle is near its traction limits. On the same page, it says the VDC off light comes on when the VDC off button is pushed, which switches off both VDC AND traction control. Now on to page 5-27. It talks about VDC using brakes and reducing engine power to keep the car on the steered path i.e. prevent over/understeer. It states that the VDC also uses active brake limited slip (ABLS) to improve traction. It says the ABLS applies brakes to one of the driven wheels if it spins too fast on a slippery surface in order to divert power to the other wheel. This sounds a lot like the traction control system mentioned previously on page 2-14. However, the words "traction control" are never explicitly stated in this section. To make things worse, the manual seems to contradict itself. It further states on page 5-27 that even if the VDC is turned off, the ABLS system remains operational, and if it is activated it will cause the slip indicator light to blink. Note that this contradicts what was mentioned in page 2-14, that the vdc off button turns off both the VDC and traction control. However, it does seem consistent with what I experienced during my drive, with the slip light blinking even though I didn't feel any braking effort on the rear wheels. Is this an error in the manual, or are traction control and abls different things?