Constant CDL

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Nov 5, 2006
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1,149
I’m having a dickens of a time getting my CDL to engage & disengage in a dependable, predictable, manner. (Done an LS swap, so I have a cobbled together electrical system)

I did the Pin 7 mod + CDL switch, to try and bypass any system checks I haven’t got right.

I can pretty much engage CDL, with the switch, when I shift back into gear 100% of the time. But when I try to disengage CDL with the switch, sometimes it does, sometimes it doesn’t. If I am heading to the trail, need the axle lockers, I would rather drive 2-3 hours on the highway with CDL engaged, just to be sure I will have axle lockers on the trail.

What is the harm with driving highway speeds, dry pavement, with CDL engaged ? (Trying to figure how much time I should spend trying to get this right, before hunting season)
 
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Feb 7, 2009
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2,805
The shifter shouldn’t be controlling the cdl if you pulled the 7pin wire. If you are driving with cdl locked on you are in a true 4x4 mode no slip between axles. If you have front drive flanges then this won’t be good, with front locking hubs you could leave the hubs unlocked and be ok. Are you sure you pulled the correct wire during the pin 7? If you did the switch should lock and unlock when you push the button and shifter won’t lock or unlock when shifted to low. If that is all correct I would like at the switch on the front of the tcase pass side
 

mudgudgeon

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I can pretty much engage CDL, with the switch, when I shift back into gear 100% of the time. But when I try to disengage CDL with the switch, sometimes it does, sometimes it doesn’t.

What do you mean "when I shift back into gear"?

You should be able to engage/disengage e CDL while driving. Locking is simply a matter of hiring the button, it will engage when things line up. BUT it's unlikely to unlock if there's load on the drive train.
In a manual, it's easy to just depress the clutch and coast to unload the drive train so the CDL can disengage. (You could shift your auto trans to neutral and coast to achieve the same thing). Some times as well as coasting, you need to gently steer left and right a little so you get some movement at the centre differential to allow it to unload.
If there's load on the drivetrain, and you're trying to unlock it while stationary, nothing is going to happen until the the vehicle moved, wheels rotate, and the drivetrain has a chance to unload.

Driving in hard top with CDL locked is not great. It puts additional strain on the drivetrain, causes wheels to break traction, and will affect the way it corners and steers too.

On dry roads, maybe not a problem. On wet roads, it will probably be enough to cause a loss of traction in the front.

Many cruisers inadvertently get driven with the CDL locked because someone's unknowingly but the switch, or unlocking it has been forgotten after wheeling. It's not gonna instantly hand grenade something if you leave it locked on a paced surface (unless something's about ready to give up anyway). I certainly would not recommend you make a habit of driving it in owned roads with the CDL locked though.
 
Joined
Nov 5, 2006
Messages
1,149
What do you mean "when I shift back into gear"?

You should be able to engage/disengage e CDL while driving. Locking is simply a matter of hiring the button, it will engage when things line up. BUT it's unlikely to unlock if there's load on the drive train.
In a manual, it's easy to just depress the clutch and coast to unload the drive train so the CDL can disengage. (You could shift your auto trans to neutral and coast to achieve the same thing). Some times as well as coasting, you need to gently steer left and right a little so you get some movement at the centre differential to allow it to unload.
If there's load on the drivetrain, and you're trying to unlock it while stationary, nothing is going to happen until the the vehicle moved, wheels rotate, and the drivetrain has a chance to unload.

Driving in hard top with CDL locked is not great. It puts additional strain on the drivetrain, causes wheels to break traction, and will affect the way it corners and steers too.

On dry roads, maybe not a problem. On wet roads, it will probably be enough to cause a loss of traction in the front.

Many cruisers inadvertently get driven with the CDL locked because someone's unknowingly but the switch, or unlocking it has been forgotten after wheeling. It's not gonna instantly hand grenade something if you leave it locked on a paced surface (unless something's about ready to give up anyway). I certainly would not recommend you make a habit of driving it in owned roads with the CDL locked though.
Did a little more experimenting & it looks like I can get it to unlock reliably by shifting into reverse, probably goes to your comment on only disengaging with no load
 

LandLocked93

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Jun 11, 2018
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Colorado
+1 - drive line load is a critical facet to using mechanical locks.

"T'was always thus. And thus t'will always be." - Robin 'Keating' Williams
 

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