why does CDL lite take a while to come on?

[IXXI]

can anyone describe whats happening down there in the TC-- when i hit the switch, the lite on the dash comes on, but sometimes it can take a lot longer than other times. usually takes longer if the road is dry, i've noticed (no, i don't need it locked then, i'm just checking it out of compulsion.) do the wheels need to feel a little bit of slip first?

related question: occassionally after hitting the switch and unlocking (light goes out), the ABS light stays on until i turn off ignition. other times, that light goes out too-- usually a beat or two after the difflock light goes out. is this normal?

 

[Mickldo]

The selector hub in the t/case has to align itself so it can engage. If the hub doesn't line up it won't engage. To line them up the front and rear tailshafts need to rotate at different speeds until they line up. The same thing happens when disengaging the CDL the shafts need to unwind to release the load before the hub releases. Sometimes you need to drive for a little while before the CDL releases.

 

[Tooth Fairy]

The diff locks will do the same thing. Just be patient.

 

[IXXI]

Ah, I see. Totally makes sense.

What about the ABS light staying on-- I thought ABS was more electrical and less mechanical?

 

[george_tlc]

That's a feature. If you have the CDL on ABS deactivates. If you exceed 30mph (from memory) with the CDL on then the ABS system is deactivated (even if you deselect the CDL) until you turn the engine off and back on.

So, on a gravel roads etc, where ABS is less than useful, you can get up to 30mph, engage the CDL, let the ECU then disable ABS, disengage the CDL and the ABS will remain deactivated regardless of speed you're travelling. When you need ABS again, just cycle the engine off/on and you'll have the brake system nanny (ABS) back in operation.

george.

 

[IXXI]

Thanks George and everyone else.

I'm now much more edumucated.

 

[jcolvin]

Sometimes a slow-to-engage CDL is an early warning that it's starting to cr@p out. If it has gotten moisture into it somehow, it will get slower until one day it will stick. Then the motor will burn out and you will need a new CDL actuator.

If it takes more than a few seconds to engage, I'd recommend pulling it off and opening it up to check for water inside. It would also be a good time to check that the breather hose is still attached to the nipple.