D2 CDL Light not engaging after new tranfercase

Mike26

Well-known member
Jan 29, 2008
238
0
Dallas
I have now replaced my '01 CDL transfercase with a freshly resealed '04 transfercase. The '04 transfercase has two CDL sensors in the front output of the case, as opposed to the one sensor that my '01 had. I cut and crimped the old wires and attached them to the front most sensor on the '04 case, which is in the same physical location of the case as the old one and I just left the rear most sensor unplugged. The CDL feature works, but the light does not illuminate on the dash anymore. I'm curious if anyone else has run into this issue as well and if it was resolved by wiring into the rear most sensor instead of the front one.

On my 2001 D2 the CDL light has always properly worked after I did the D1 shifter linkage and the re-wire to the BCM (to make the TC/ABS not freak out when turning the vehicle off and back on with CDL engaged)
 

JohnB

Well-known member
Oct 18, 2007
2,225
1
Oregon
Nothing to add with what you did but when I added lock linkage to my 99 the light goes on sometimes and takes a while to go out even though I know the mechanical's work.
Maybe just a bad switch?
 

Mike26

Well-known member
Jan 29, 2008
238
0
Dallas
Yeah, the switch might be bad. Its been too cold out to mess with it. My next plan is to try splicing into the rear most CDL switch instead of the front one. if that doesn't work, I'll attempt removing the switches to bench test their function, that'll just be a PITA due to the tight working space.
 

WaltNYC

Well-known member
Mar 3, 2010
414
1
NYC
56081

Differential lock warning lamp switches - Vehicles from 03 model year
Vehicles from 03 model year are fitted with two differential lock warning lamp switches.
Both switches are of a new design and are fitted into the top of the front output housing. The switches are connected
to the SLABS ECU and are operated by movement of the selector shaft.
Both switches have an aluminium washer which seals the switch to the casing and also sets the switch position,
removing the requirement for a setting procedure.
Both switches are connected in parallel to earth when the differential lock is engaged. This earth is sensed by the
SLABS ECU which illuminates the differential lock warning lamp in the instrument pack.
What a weird arrangement. The diagrams aren't much help. Your '01 doesn't have wiring for the rear switch but that may be causing a ground condition and negating the function of the front switch.
 

Mike26

Well-known member
Jan 29, 2008
238
0
Dallas
Finally warm enough to mess with it. Both the front and rear sensors were junk and didn’t work properly when bench tested. Replaced the front most dead sensor with a new sensor (believe it was a reverse sensor for a R380, but same deal) and spliced it into place. Left the rear most sensor in place unplugged since my ‘01 doesn’t care about it. Light on the dash works properly now, problem solved.