CDL indicators but diff not locked?

Wes_in_va

Member
May 26, 2018
8
0
Roanoke VA
2004 Disco 2 SE
I started getting an occasional and random 3 beeps a while back. There would sometimes be occasional flashes of the CDL indicator lamp too but it would be brief.
I put the CDL lever through the paces and the beepin and flashing stopped for a while.
It came back occasionally about a week later, and I?ve had it occasionally for a few weeks.

The other day on a longer drive the audible indicator and the lamp were on and off pretty much the whole trip. I checked to see if the differential was really locked but it wasn?t.
The CDL lever appears to work since when I lock the diff it feels as if it?s engaged.

The damn beeping is driving me crazy. I?ve read a bunch of stuff about a stick CDL and I?ve seen references to an indicator that?s wonky but I?m not sure how best to address my situation? Does it sound like a bad sensor, or something loose in the linkages? Am I risking anything by driving the truck?
 

discostew

Well-known member
Sep 14, 2010
7,706
1,015
Northern Illinois
I think the switch could be sticking. I would pull it off the transfer case and check it. Its got a little steel ball at the end of it and yours is probably sticking in. If it is sticking first try to clean the thing out with brake cleaner before you replace it. I usually get them to free up.
 

Wes_in_va

Member
May 26, 2018
8
0
Roanoke VA
Will do.
Does that switch just control the indicator? The actual diff lock is mechanical linkage, right?
I just don?t want to damage anything by driving it
 

Jeff Blake

Well-known member
May 6, 2016
429
16
Pacific Beach, San Diego
The switches are quite sensitive, and there are two on the 04 case, right next to each other. Might need to shim another washer under one of them - I had to do that when i rebuilt the case

You could unplug the switches one at a time and drive around to determine the culprit
 

kcabpilot

Well-known member
Mar 26, 2006
334
1
California
I have an '01 so my diff lock was not connected from the factory and when I installed a D1 shift lever this happened to me - the light came on and stayed on even though I had only used the lock a few times for test purposes when I first hooked it up. I engaged and disengaged it a few times and the light went out and has never given me any trouble since, about three years now. I think the switch was just a bit sticky since it had never been used for the first fourteen years.
 

Jeff Blake

Well-known member
May 6, 2016
429
16
Pacific Beach, San Diego
Yeah the switches err on the side of "locked", i.e. the diff lock light can be on, but you are not necessarily locked (yet). If the diff lock light is off, then you are 100% open. Takes a good wheel spin (or aggressive turning) before it engages or dis-engages
 

Jeff Blake

Well-known member
May 6, 2016
429
16
Pacific Beach, San Diego

Good clip, that shows how it works when the dog clutch is aligned

Here's a video I made a few months ago, https://www.youtube.com/watch?v=V1HR5ff7QNQ

At around 30 seconds you can see how it works if the dog clutch is not aligned (it adds spring tension, and engages once the center diff spins)

Notice I had to use a second washer under the front switch so that the selector fork didn't stick