Active TRAC sounds and AHC

[LX470Pilot]

Yesterday I went off on a dirt road in the local mountains above L.A. which involved several tight switchbacks at a steep (for me) angle (don't have an inclinometer, but I'd say about 15deg) and happened to engage the Active-TRAC.

I've only done this a couple times before, and don't remember this noise from the front axle:

a clicking/clunking sound when the dash-light would flash, and a sprung noise when it stopped.

Sound comes from inboard side of drivers-side foot well.

Sprung noise - like a heavy piece of metal being pulled back to a stop with enough force to cause it to bounce, or vibrate slightly.

Not sure how better to describe it....

Anyway, is this normal? Maybe I'd only engaged the rear axle the last couple times and so hadn't heard this?


AHC - upon exiting the dirt road, I pushed AHC down to Normal (having been on High for the duration of the dirt road for rocks and such) but it just blinked N while H stayed solid for about 1/2 mile - in 4H and going about 30mph.

It works fine now, H, N, L on command and automatically per driving speed.

Any thoughts?

-LX Pilot

 

[Val678]

Duno abou the A-Trac but your AHC Sensor could have been the culprit, wouldn't worry about it if it went back to N.

 

[ShottsUZJ100]

TRAC sounds are normal. Just make sure for safety's sake that you lock your CDL if cross-axle'd terrain is in store. TRAC with an unlocked CDL can result in no braking for a short time and could be dangerous...especially climbing a hill, losing traction, rolling backwards and not having brakes. This will not happen with a locked CDL.

 

[1loudLX]

Thats a good thing to know, thank you Shotts.

 

[EdsCruisin]

TRAC sounds are normal. Just make sure for safety's sake that you lock your CDL if cross-axle'd terrain is in store. TRAC with an unlocked CDL can result in no braking for a short time and could be dangerous...especially climbing a hill, losing traction, rolling backwards and not having brakes. This will not happen with a locked CDL.

So, when I was trying to ascend a steep slippery slope today, my Active Trac engaged as well, and it was Rough to say the least. Circumstances being what they were, I didn't get a chance to try the diff loc. Are you saying that the diff loc would have been the appropriate choice? Or the horrible crunching in my front end is OK for the short term and would have helped me up the hill?

 

[LX470Pilot]

forgive my ignorance, but Shotts reffered to crossed axles:

do you mean Fr - Left down/Right up and Rr Left up/Right down - so that looking at the vehicle from either end produces an X of the axles?

Or did you have a different meaning in mind?


Thnx,

LX Pilot

 

[tech_dog]

I'm also curious about an elaboration of the loss of braking when unlocked.

Can you give more info on why this would happen?

 

[ShottsUZJ100]

It is dangerous to climb hills especially with cross axled sections WITHOUT locking the CDL. Whenever in this terrain, the locking the CDL is the FIRST thing you should do so the power doesn't slip between the F&R axles.

Second...if you lose traction while climbing, begin to stop progress and apply your brakes so that you won't roll down hill backwards.....with:

The CDL locked: Your brakes will activate and you're safe

The CDL UNlocked: The TRAC CPU can battle the ABS CPU and you can actually have brakes modulating and you roll backwards WITHOUT brake control. This is common on the 100, Range Rover, and Discovery's.

YOU NEED TO LOCK YOUR CDL IN THE TOUGH STUFF!

 

[EdsCruisin]

It is dangerous to climb hills especially with cross axled sections WITHOUT locking the CDL. Whenever in this terrain, the locking the CDL is the FIRST thing you should do so the power doesn't slip between the F&R axles.

Second...if you lose traction while climbing, begin to stop progress and apply your brakes so that you won't roll down hill backwards.....with:

The CDL locked: Your brakes will activate and you're safe

The CDL UNlocked: The TRAC CPU can battle the ABS CPU and you can actually have brakes modulating and you roll backwards WITHOUT brake control. This is common on the 100, Range Rover, and Discovery's.

YOU NEED TO LOCK YOUR CDL IN THE TOUGH STUFF!

OK, to further the ignorance - I get the last message about the locking the CDL, but I still have questions:

I have never had this issue in the past on other 4x4's. I would just put it in 4wd (hi or lo) and drive up the hill. I expected the same with the LC. I am not talking about rock climbing or traversing a ditch. I am talking about driving up a wet, grassy hill (i.e. surface mud).

Does the CDL disable active trac?

 

[ShottsUZJ100]

OK, to further the ignorance - I get the last message about the locking the CDL, but I still have questions:

I have never had this issue in the past on other 4x4's. I would just put it in 4wd (hi or lo) and drive up the hill. I expected the same with the LC. I am not talking about rock climbing or traversing a ditch. I am talking about driving up a wet, grassy hill (i.e. surface mud).

Does the CDL disable active trac?

When you put your other 4x4's into 4WD it locks the axles together like your CDL switch does in the 100. Plus, they didn't have TRAC mixed into the equation either. And no....CDL locked and TRAC is the combo you need the most!

 

[EdsCruisin]

Thanks. I'll have to get out this weekend and try this again.

 

[tech_dog]

The CDL UNlocked: The TRAC CPU can battle the ABS CPU and you can actually have brakes modulating and you roll backwards WITHOUT brake control. This is common on the 100, Range Rover, and Discovery's.

I went looking for other discussions on this, but didn't find any. Is this really happening to people, or is it theoretical?

 

[ShottsUZJ100]

I went looking for other discussions on this, but didn't find any. Is this really happening to people, or is it theoretical?

I made it all up. ;p