What does this button do...

READ MY REPLY (#13)... then ask me a specific question if that doesn't answer it for you.

Quick press increases the traction control ability because that turns OFF the engine output regulation (TRAC OFF MODE/ AUTO LSD MODE).

STOP ROLLING, PRESS and HOLD IN for a few seconds, turns off all VSC and TRAC systems (Open Differentials). Press again to go back to orig. mode, or re-start the truck.

 

If so why did my 2009 Prerunner have it?

 

Your truck does not have a mechanical LSD. Yes, it uses the brake to slow the wheel with no grip to transfer power to a wheel with grip. VSC works to limit the drift in a skid situation by applying braking to one of the rear wheels and keep your truck pointed where you want to go and in control.

Pressing the button quickly will leave the traction control braking on but allow you to floor the engine. Holding the button for more than three seconds will turn your truck into "open diff" mode as you describe it. Remember though, VSC will still reactivate no matter what you press at speeds above 30 mph.

 

Actually VSC (if turned off) will reactivate at any speed if the truck is in a dangerous condition, to prevent you from spinning sideways or rolling. The 30 mph reactivation is only in the AUTO LSD/TRAC OFF mode, which shuts off VSC automatically up to 30 mph.

 

Your 2WD had DAC? Maybe just the button by mistake?

 

Your Prerunner did not have DAC, only 4WD AT TRD OR has it. I think you and @jmaac are probably talking about two different things.

 

Okay David, I re-read #13 and have just one question...you say anything in bold is a change for 2012 and up...mine is a 2011...is there anything in your #13 that would be different for my truck?

 

OK, sorry I thought we were discussing 2012 + modes... I have a 2010... In the link I provided in that #13 post, if you click it you will see:

2009-2011:

Press Nothing...

H2= TRAC (Limited Slip with Engine Output Regulation)
H4= TRAC (Limited Slip without Engine Regulation, front and rear)
L4= No Traction Control
-----------------------------------------------------------------------------------------
Quick Press (VSC OFF SWITCH) moving or stopped...

H2= AUTO LSD (Limited Slip without Engine Output Regulation, VSC OFF to 30 mph)
----------------------------------------------------------------------------------------
Press and Hold In 3-5 seconds (VSC OFF SWITCH) while stopped...
H2= VSC OFF (No Traction Control)
H4= VSC OFF (No Traction Control)
----------------------------------------------------------------------------------------
Off Road TRD:

Quick Press of RR Lock Switch= Rear differential Locker (L4 only on 4WD models)
L4 Only: Quick Press of A-TRAC Switch= Front and Rear near-no slip traction control. A-TRAC works the front tires if speed drops below 3 mph, if the Rear Locker is also on.
======================================================================

 

Okay David...thanks for your wealth of knowledge, but a couple clarifications...

Are saying with 'no press' in L4, it is an open diff? In fact, it looks like L4 is open diff all the time?

And a 'quick press' does nothing in H4?

Thanks!

 

L4 (unless you are an Off Road TRD) has NO traction control... the VSC button does NOTHING in low range. Open diff only, yes. [keep in mind all our 2009+ trucks have open differentials, except when a locker is activated, but I know you mean no traction controls]

In H4, 2009-2011, a quick press does nothing at all... no light, nothing. The H4 mode already is in the better TRAC OFF (AUTO LSD) choice, only they didn't call it TRAC OFF, since there was no option of on or off with the engine regulation then.

Non Off Road TRD 4WDs have performed the 4 LO TRAC MOD to get traction control in L4, with great results over stock 'open differentials'.

The Off Road TRD has A-TRAC in L4 (with a push of the A-TRAC button) which is a higher degree of traction control than the TRAC in L4 MOD... very very close to having lockers on the front and rear, as any spinning tire is not slowed, but stopped and matched with the rotation speed of the traction tire on each axle. Lockers match the rotation across an axle as well, but do not auto-free when no longer needed to allow steering ease. We also still have the rear differential locker, as all Off Road TRDs before 2009 had.