CDL Question

[Ecoman]

Ok so this might sound like a dumb question but If I fitted a Centre Diff Lock Switch and wired it up would that mean that every time I selected low box I could turn off the diff lock if not needed? Mine is a 1993 auto with an overdrive button on the side of the gear selector. I find it a pain when off roading that when I select low box the CDL is automatically engaged. If I get into a tricky situation and need both front and rear diffs locked but need to turn the steering it starts to wind up the transmission and the truck starts banging out a tune. Not nice

 

[adrianr]

Not quite.

You need to pull a pin on side of the transfer box as well. then you have to press switch in high or lo for cdl to engage.

much better.

 

[Ecoman]

Wow thanks for the quick respose.

Ok so can you elaborate a bit for me please. I'm fairly new at the mecanical/electrical workings of an LC so still finding my way about.

 

[Cptsideways]

There are two plugs on top of the transfer box, one is the CDL in low range switch, pull one at a time & you'll find the right one.

 

[Gav Peter]

It is a very simple mod Bill & so very much worthwhile. I'd been driving Muxley around without doing it for ages & driving offroad with that terrible auto shift pattern in low box...

We had some time to kill on a trip along Strata Florida so I did it under the supervision of Chris J & it transforms the driving experience!!!

I think if you search about there's a pic of the plug to remove...

But as Declan says, there's only a choice of two!!!

 

[adrianr]

No problem!

Get switch first!

Easy to fit into dash - the wiring is in their already ready for the plug. You may / may not have to fish about for it.

then get under truck

lie with your head under the transfer box - feet towards front of truck.

put your hands up around the right side of the thin end of the transfer box at about the 1 oclock position if you we looking at transfer box sat up and towards front of truck.

there is a connector on there that you want to undo.


hop into truck
stick it in low ratio
should NOT have orange centre difflock light show up.
press your new switch
if it now lights up you are good to go

back under truck

get some nitrile gloves
cut thumb off two
smear of di-electric grease on end of both plug ends, more in the thumb part of gloves.
put over end of each and cable tie neatly and tightly top waterproof same.

clean up

now you have gull manual control in low and high ratio of centre box.

This is on mine - pointing to it from high up on the other side (left side looking at the transfer box - rear of truck is to the right in this pick

 

[Gav Peter]

One for sale here - no link to me or try Karl.

 

[Towpack]

On the manual LC's it's just a case of pulling the plug on the Xfer box but on the auto's there's also a mod to a plug on the 4WD ECU that alters the shift pattern when in low:

http://www.sleeoffroad.com/technical/tz_cdl_pin7mod.htm

 

[Gav Peter]

If you want to retain the awful lowbox shift pattern, do the 7-pin mod; if you want it to drive better & get the full benefit, DONT!!!

 

[Ecoman]

Blimey thanks guys. Couldn't ask for a better response

Sounds like its a mod worth doing then. I will get onto it ASAP

 

[goingdownsouth]

After reading this I've got a question.

Mine is a 1994 Auto VX non-import with OD switch on Gearlever.

I've already installed the CDL switch in the dash. There was an existing male connector with a bridge wire stuck into the female connector in the dash. I disconnected this male connector with the bridge wire and plugged in the CDL switch.

When I'm in High and I press the switch the orange light shines indicating difflock engaged. When I engage Low it also lights up.

Do i still need to fiddle about underneath the truck?

 

[Chris]

Yes.

Chris

 

[Dave Docwra]

Chris, Did you misspell search..

 

[Chris]

Yes.

Chris

As in search the previous page of this thread, Dave?

Strictly speaking this has been answered on many occasions, including in this actual thread as it happens, but one more time won’t hurt.

When you shift into low ratio in the auto, you would expect the gear change intervals to be the same as high range just in a lower range; in other words if you had to nod when you thought it needed to change gear, you would have the same feel brrrrr - change, brrrr change, brrrr change - yes? Just like when you drive a manual.

But this is NOT what happens, you get brrrrrrrrr, whirrrrrrrr, whine, screeeeeeam, thunk, second gear …. Holy S***!!

Off road this is useless as every time it changes you lose traction, when you need changes to be as smooth as possible. You rev the nuts off it on a rockly climb and then it flings you into second at 3000 rpm like F1 launch control

The CDL switch mod doesn’t affect this. The OD drive button has nothing whatsoever to do with this either. If you go underneath and disconnect the plug that is shown on page 1 then suddenly the low ratio changes return to the same intervals as high range. Off road suddenly becomes a whole new experience. This is positively the last time I am answering this question. Ever.

Chris

 

[Chas]

This is positively the last time I am answering this question. Ever. Chris

But I just bet it gets asked again

 

[Ecoman]

Excellent explanation it was too

I must say I have never been impressed with the autos gear change when in low box. Glad there is something I can do about it

 

[Chris]

Yeah, they're bonkers aren't they. Now what I have never been quite sure of, is the pin 7 mod. Given that we've established what the dash switch addition does and the unplugging on the T box, what's this much vaunted wiring mod for? I keep reading about it ( I know how to do it) but I don't understand what it achieves. If it restores the stupid gear changes back again, then just don't unplug the loom in the first place and have CDL control and stupid change intervals.

So let's finish this thread (for the last time, ever) with a clear explanation of the pin 7 shenanigans.

Chris

 

[Jon Wildsmith]

The switch on the transfer box that detects you putting it into low range is connected to the gearbox ECU, so it knows to change the shift programming, and also pin 7 of the transfer control relay which is what locks the CDL automatically when you select low range. By disconnecting pin 7 of the transfer control relay you disable auto locking of the CDL but the gearbox ECU still knows you need the low range shift programming If instead you disconnect the switch on the transfer box then neither the gearbox ECU or the transfer control relay know when you select low range so there's no auto locking of CDL and no bizarre shift programming

 

[Chris]

By disconnecting pin 7 of the transfer control relay you disable auto locking of the CDL but the gearbox ECU still knows you need the low range shift programming

But why would you do that?

I have read that about 6 times now and I think I get it. But I don't understand it.

If you do pin 7, do you then leave the plug in the T box? Then how do you lock the CD? I presume you still need the switch in the dash. So in short pin 7 retains the stupid ratios, but give manual control on the CDL?

It's late I am tired, but that how it reads. I think.

C

 

[Jon Wildsmith]

It's late I am tired, but that how it reads. I think.

Yes, that's correct.