4-Low safe on pavement? (3 Viewers)

[RiverRatMatt]

The best place to start with this question is how does the full time 4wd work? Is there a dynamic power shift between front and rear wheels or is it always 40/60 power split?

With that in mind, is it safe to use 4-low on dry pavement or other surfaces? I know part time 4wd vehicles with a 50/50 split need the front end to have some slippage due to the gears not matching up correctly, otherwise you can grenade your transfer case.

Not many reasons you'd need 4-low on pavement but it it would be good to know.

 

[Spike555]

The only difference between 4-hi and 4-lo is the gear ratio. You can use 4-lo all you want anywhere you want for as long as you want.
Just do not use the CDL on dry pavement. Even in 4-hi.

But you can use the CDL for as long as you want and for any speed you need.
I like to use in during heavy snow on the highway.

 

[Trunk Monkey]

Great topic that's covered in the owner's manual. Give it a read, there's that a dozens of other good bits of info.

 

[Somebodyelse5]

The best place to start with this question is how does the full time 4wd work? Is there a dynamic power shift between front and rear wheels or is it always 40/60 power split?

With that in mind, is it safe to use 4-low on dry pavement or other surfaces? I know part time 4wd vehicles with a 50/50 split need the front end to have some slippage due to the gears not matching up correctly, otherwise you can grenade your transfer case.

Not many reasons you'd need 4-low on pavement but it it would be good to know.

Check your manual. 4-Low will automatically lock the center diff, which should not be used on pavement... you will get drivetrain windup and potentially brake some things. This can be disabled, read here --> LX470 Cabin Air Filter Replacement DIY (ignore the title, it links to a specific page in the thread that got off topic)

 

[SlowBuild]

Check your manual. 4-Low will automatically lock the center diff

This is only true for early model years.

 

[Ohthetrees]

This is only true for early model years.

This is the crux of the matter. If your year automatically locks the center diff when you put it in low, you should not drive in low on pavement or any high traction surface. If your year doesn’t lock the diff (my 2001 doesn’t) then it is fine to drive on pavement in low, with all diffs unlocked.

 

[Somebodyelse5]

This is the crux of the matter. If your year automatically locks the center diff when you put it in low, you should not drive in low on pavement or any high traction surface. If your year doesn’t lock the diff (my 2001 doesn’t) then it is fine to drive on pavement in low, with all diffs unlocked.

See, I couldn't find anything that has the year cutoff. Anyone know when it changed? My 99 locks

 

[DirtDawg]

See, I couldn't find anything that has the year cutoff. Anyone know when it changed? My 99 locks

I believe ‘98 & ‘99 auto lock as my ‘00 does not.

 

[RiverRatMatt]

Thank you all for the replies!

I'm pretty sure my 2000 does not lock, at least the diff lock light does not automatically come on in 4-low.

 

[geanes]

I believe ‘98 & ‘99 auto lock as my ‘00 does not.

My understanding has always been that the 98 and 99 were the only years the auto-diff lock was featured.

 

[flintknapper]

My understanding has always been that the 98 and 99 were the only years the auto-diff lock was featured.

^^^^ This is my understanding as well. And of course the 'Pin 7 mod' will let you choose to lock (or not) the Center Diff in either high or low range.

 

[LandCruiserPhil]

I use low range on pavement at the boat dock all the time and now with PT I have no center diff lock as its always locked when in 4WD and I still use it on the ramp

 

[lxfguy]

Lol everyone's fine cuz I launch my car in low on pavement all the time.

 

[MongooseGA]

I'm sure I've read it before but since this thread is going...

Can anyone confirm if the CDL light comes on the dash when an older truck is put into 4-lo and the CDL autolocks?

Mine is a newer model but this might be useful info for owners of 98/99 trucks. In my '99, I do not remember the CDL light coming on unless I specifically pushed the button, even in 4-LO.

 

[lxfguy]

In my 1999, the lights do not come on unless I push the center diff lock button.

 

[Ayune]

According to the '98 wiring diagram: The CDL dash light is illuminated when the CDL detector switch on the transfer case is depressed, no matter how the CDL is engaged. The CDL detector switch completes a direct path through the dash light to Ground, so the dash light should illuminate when the CDL is engaged automatically.

The transfer case Low detector switch simply acts as as a proxy for the manual CDL button, unless you've performed the Pin 7 mod.

 

[geanes]

Ayune is correct. On my 98, if I would manually depress the CDL button while in 4H, the light would come on and I'd hear the relay in the glovebox. When I would shift into 4L, the CDL automatically engaged and the light came on. I could push the button as much as I want in 4L and nothing would happen...not even a clicking of the relay. It was as if the button was completely out of the loop if in 4L. I did the PIN7 mod, so now I have to manually select the CDL regardless of either 4H or 4L.

 

[2001LC]

Many (including myself) have accidentally left CDL on due to no dash light illuminating. Then driven for who knows how long on dry pavement, before noticing binding in a sharp turn. Can't say I heard of any damage, although certainly not recommend.

Note: Not using CDL often enough and relay sticks that controls CDL dash light, so it doesn't always illuminate.

 

[Ayune]

Many (including myself) have accidentally left CDL on due to no dash light illuminating. Then driven for who knows how long on dry pavement, before noticing binding in a sharp turn. Can't say I heard of any damage, although certainly not recommend.

Note: Not using CDL often enough and relay sticks that controls CDL dash light, so it doesn't always illuminate.

The relays that we hear clicking behind the glove box control the actuator motor, not the dash light. The light's illuminated when the detector switch on the transfer case is physically depressed by the engaged CDL, so, barring a burnt-out bulb the detector switch is the likely culprit.

Exercising the system is definitely easy "preventative maintenance." I had to replace my CDL detector switch to restore proper operation of my dash light. NAPA p/n NS6421 is the $29 solution, more info here: Center Differential Lock Transfer Indicator Switch Problem

 

[krice118]

Use the pin 7 mod to make the CDL selectable on early 100s super easy mod. Search will help