VSC/A-Trac

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Permalink Reply by Boss73 on January 12, 2010 at 3:27pm

A-TRAC will only come on in 4low, and you have to press the button to engage it. SO if your in 4hi then you do not need to worry about A-TRAC.

I am not sure about the unplug wire bundle or harness. But in the Manual Transmission if you put the transfer case in 4hi that turns off VSC. Not sure if you will still get the tractions control to kick in cuz I have never tried to get wheel spin. Hope this helps a bit...

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Permalink Reply by Bz on January 12, 2010 at 5:21pm

making-sense-trac-auto-lsd-atrac-vsc-rear-diff-lock

From the blue room:

I know this topic has been discussed to death. Since many of us are new to wheelin, all of these terms can be very confusing. This info is easily located in the owner's manuel page 123-130 ish which i know most hesitated to read. I typed this out more for me to get these straighten out so I know when or when not to use them. If I misunderstood any of these concepts, then feel free to let me know. I posted this in another thread, but thought it deserved it's own.

TRAction Control system (pg 123). This is refering to TRAC. automatically helps prevent spinning of the rear wheels (2wd models) or 4 wheels (by adding brakes) when the vehicle is started or accelerated on slippery road surfaces.
Doesn't require push button activation. Works on it's own and is activated when the ignition is turned on. all FJ's have this whether 2 or 4wd model. On automatics, I am assuming this works in 2H or 4H, doesn't matter. If the system detects wheel spin, it adds brakes to increase traction.

A-TRAC is Active Traction Control system (pg 125) automatically helps prevent the spinning of 4 wheels when the vehicle is started or accelerated on slippery road surfaces. (basically same as TRAC, but only works in 4 Lo). To activated, hit the ATRAC switch, shift into Nuetral, and shift the 4x4 lever (short knob) into 4 LO. When in 4Lo, it detects wheel slippage and adds brakes accordingly to give added traction. Again, you must be in 4Lo and hit the "ATRAC" switch.

2wd models have Auto LSD (pg 127) instead of ATRAC. Automatic Limited Slip Differential uses the traction control system (TRAC) to control engine performance AND braking when one of the rear wheels begins to spin (or slip). This gives added traction to the vehicle.
Auto LSD has it's own button, found in the upper left hand corner of the buttons (found in 2wd models only). Apparrently it must be engage with the push of the "auto LSD" button when you're on a slippery surface (snow, ice, or lots o' water).
This is the 2wd's version of ATRAC found on 4wd models.

VSC (vehicle stability control) system on pg 130: integrates the control of the systems such as ABS, TRACtion control, engine control, etc to prevent the vehicle from skidding when cornering on a slippery road surface or operating steering wheel abruptly.
VSC is activated when the FJ reachs 9mph or 15km/h.
*VSC automatically turns off (VSC off light on dash comes on) when 4H/HL or 4Lo/LL is activated (AT/MT) or when the Rear Diff is locked.

Here's the conclusion....

-Both 2wd and 4wd models have VSC and TRAC. activated when FJ is started(TRAC) or when FJ reaches 9mph (VSC) and works when it's needed. No action required on your part.
-2WD models: when in snow, ice, or water, oil or anything slippery and you need a little extra traction control. Hit the Auto LSD to get added traction in the rear wheels.
-4WD models: TRAC works in 2H or 4H. when running 4 LO in slippery conditions such as snow, ice, water, oil, mud, slicks, etc. Hit ATRAC switch for added traction.

Rear Differential Lock System: for use only when wheel spinning (as oppose to wheel slipping) occurs in a ditch or on a slippery or ragged surface. Rear diff lock is effective when one of the rear wheels is spinning.
Note: use ATRAC when there is wheel slippage or partial traction.
Use RR Diff locker when there is wheel spinning or NO traction.
-Must be in LL (MT) or 4Lo (Automatics). It is also suggested that you try the LL or 4Lo 1st, it this is not enough, then activate the Rear Diff locker.
-Also mentions that a large steering effort and careful cornering is required. Means that you'll have a hard time steering, will seem very stiff.
Note: when using the rear locker the following systems do not work and their lights will come on (ABS warning light, VSC off light, and the slip indicator [ the car icon with double SS under the tires] light will ALL come on).

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Permalink Reply by 4x4CruiserGirl on January 12, 2010 at 9:54pm

Thanx for the help, BZ and Boss. I only ask because it was of no help in the snow last season (off road) and would like to keep myself from having to ask dear old Dad and his Jeep to pull me out. =(

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Permalink Reply by Bz on January 13, 2010 at 10:54am

for most snow I'd keep it in 4hi, A-Trac does like the snow, mud, or sand

The locker is a tool that should be used carefully 'cause it will drag the rear down a hill, if you are sideways across one

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