I am not sure if there is a note in the owner's manual about this (as there is with the V6 T4Rs) but if you have the V8 with full time 4WD you need to regularly shift it into 4Lo to exercise the actuator.

I recently had an issue with my 03' (~90k miles) where I got in and the center diff lock light immediately began flashing with the VSC Off light and the car had a hard time driving forward and steering. There is a TSB on here that instructs you to repeatedly short a connector to reset the YAW rate calibration to remedy this issue. After no resolution from the TSB with multiple calibration attempts I had to bring the car to the stealership. They said the issue was the motor (tech likened it to a windshield wiper motor) that shifts from 4Hi to 4Lo had completely locked up sending bad signals from the other sensors. The motor itself runs $650 to replace, but the tech 'fixed' my issue by freeing up the motor with a few hammer hits costing me $150 (took them a while to find and fix).

The tech's parting instructions where to (this is verbatim): 'throw the car in 4Lo every once and a while and beat the S@#T out of it to free up the motor'

I wouldn't use the tech's advise to the tee, but for others like myself whose T4R's are primarily street rides that don't need to use 4Lo it is a good idea to routinely put the car in 4Lo and exercise this motor. It will only take a small amount of time and could potentially save you a good deal!

Anyone have a copy of (or link to) the related TSB?

http://www.toyotapart.com/VSC_LIGHT_...T-BR03-005.pdf

I put mine in 4LO every month and drive through my neighborhood. Unlocked of course.

So how long should you drive in 4 LO? I just put mine in 4LO and drove down the street.

Should I drive further in 4LO?

This is all in the manual. If memory serves me correctly, you're looking for 10mi in hi and lo.

So the symptom was a locked center diff but the cause and fix was the low range actuator, is this correct?

jeez, how fast can you go in 4lo? 10miles sounds like a long ways on the streets...

I think the owners manual just says to drive in 4hi once a month for about 10 miles to lubricate the front drive components. Dosen't say anything about excersing the actuater or about driving in 4lo. 10 miles of 4 lo would be somewhat rediculous every month.

I wouldn't think that you would need to drive 10miles in 4lo to exercise the motor. I think it would be more beneficial to engage 4lo for a little while then back to 4hi then back to 4lo and so forth, maybe for a combined total of 10 miles. Even that seems long unless your offroading.

IMHO the key is to cycle it in and out of 4lo a couple of times/month. In a parking lot is fine... Driving more than a few feet in 4lo is unnecessary.

Using 4hi monthly is the mode that should be driven a few miles to bring the temp of the front axle up a bit and to splash oil throughout the axle.

Does the manual say 10 or 30miles I don't worry about because I love the full-time 4wd feel, especially in the rain and drive mine more than 30miles a month in 4hi.

Since this thread title states it's for full-time 4WD, exercising 4Hi doesn't matter since you are always in 4Hi.

I exercise my 4Lo a couple times per month.

Exactly, its the actuator you are exercising, not the 4lo itself.

I do mine about once a month.

Just 10 miles per month.

in foul weather, it'll see more than 10 miles a month. I've forgotten during the sunny months and skipped a month.

This is correct.

Also to a bunch of the other posts the title states this is for full time 4WD V8's so we are always in 4Hi.