CDL + ABS Lights Do Not Illuminate (2 Viewers)

[brakasha]

Hi gang,

On a trail in MA the other day, went to engage 4 lo (no pin 7 or switch mod) and the CDL/ABS lights stayed off. Figured no problem, must be the switch on the T case; I'll just pop it off, exercise it, pop it back on like last time. While doing this, I figured I would bridge the pins on the harness to see if the lights would come on: no dice. What else can cause the computer not to recognize the center diff being locked? Are there other switches, wires, harnesses, fuses, etc that I should check? The diff definitely locked: the entire feel of the rig is pretty obviously different in 4 lo (bigger turn radius, gearing obviously higher, etc etc).

The ABS light illuminates on startup, so it's not the dash indicator itself. Additionally, when attempting to engage the factory lockers, the lights don't come on at all, even just to blink and not engage. I haven't listened for the actuator motors yet, but I figured first things first, let's see if we can get the computer to recognize the CDL engaging.

Any ideas or personal experiences with this issue would be hugely helpful.

 

[george_tlc]

Checked the 30A Diff fuse? It's common to both the CDL and F/R lockers.

Adding your vehicle year to your signature would help folk not have to guess what you have...

Download the free 1996 EWD - it will help you follow the wiring/connections.

cheers,
george.

 

[brakasha]

Haven't checked the fuse. Will do that next.

Some more background: it's a 1996 FZJ80, stock everything relevant to this particular issue.

I recently changed out the starter, which sits right near two harnesses in the lines from ECU to diff lock switches that pass directly past it, which I believe I disconnected to create the little bit more space needed to reach the bolts on the starter a bit easier. They're connected now, but maybe I bent some pins or something? I'll check those.

I'm hearing the relay click on/off in the DS footwell when switching from 4hi to 4lo. I can also hear a clicking from underneath the vehicle while sitting in the driver seat when engaging/disengaging 4hi/lo, not sure if that's the motor or not.

I have now pulled and exercised all 3 switches on the Tcase (CDL switch, neutral, and position sensor).

Maybe try some percussive maintenance on the solenoid box? I think the clicking noise from underneath is the CDL engaging, so I don't think it's mechanical but rather electrical. Once again, jumping the tcase CDL switch harness does not cause the dash lights to illuminate so I'm sort of at a loss here.

I know there are like a million threads in here about this issue, but most just say "swap out the tcase switch" or have links to threads about replacing the actuator motor.

Anyway, hopefully someone has had this exact problem that just happens across this thread and blows my mind.

 

[george_tlc]

Again, download the FREE 1996 EWD (pdf) - couple of minutes in search will find you a download link. Then you can fault find versus trial and error...

Given that even if the CDL switch/sensor doesn't indicate LOCK, you will have flashing F/R difflock lights if you attempt to lock the lockers, and you say you have NO lights at all, you need to find the things that are common to both systems. Fuse is the first step.

cheers,
george.

 

[TossYoda]

don't forget both sensors (switch) on the T-case have to work; the cdl sensor and the L4 sensor; check them both. that was my issue; both sensors were not working right; when I cleaned one and jumped the other I got lights. So I replaced both and all was well.

 

[brakasha]

Thanks everyone who responded. I checked the EWD (now have the FSM and EWD downloaded on my tablet... holy crap, what a resource!), and turns out one of the ground points for the CDL system is in the PS footwell... right behind where I was messing around while rebuilding the AC system (expansion valve as it just so happens). I guess I hadn't secured the ground firmly or something because after just unplugging and replugging the harnesses back there, everything works. And even better: the front and rear lockers both engaged! On the first try!

So thanks again for the suggestion, George. Huge help.

Cheers,

C

 

[burbuja96]

Where is the location of the 30A diff fuse please?

 

[brakasha]

In the fuse block under the OBD2 diag plug below and to the left of the steering column.