CDL issue - '96 LX450 - Resolved

Joined
Dec 8, 2016
Messages
17
Location
Columbus, OH
Editing this thread so my stupidity doesn't confuse someone else who stumbles upon this in the future.

1996 Lx450, 152k miles, NO front or rear lockers.
CDL Dash Switch, Pin-7 Mod.
4WD High and Low work fine, but the CDL hasn't locked since the day I bought it.


When shifting into 4WD Low, or when pressing the CDL Dash on the dash, I could hear the Center Diff Lock Control Relay but I was never able to hear the CDL Actuator wind up & my CDL / ABS lights never came on. Jacking up a tire and spinning it while the Transfer Case and Transmission were both in neutral confirmed that my CDL was in fact unlocked. To add to my confusion, while driving in 4WD High under acceleration or deceleration the Center Diff Lock Control Relay in the driver side footwell would chatter / click like crazy ONLY if the CDL switch on the dash was turned off. Activating the CDL switch was the only way to get the relay chatter to stop, even though it never locked the center diff. Before I installed the CDL switch it was chattering like this.


*** Extreme sleep deprivation, multiple beers, and 100F weather are not a good combination while troubleshooting. This led to many mistakes, a ton of headache, and spending ~$800 on parts I didn't even need ***


Most signs I saw online pointed to the L4 Position Switch on the transfer case. I wasn't thinking straight, and kept fooling with the CDL Indicator Switch on the front of the transfer case thinking it was the L4 Position Switch and it really screwed me over. Jumping this plug caused my CDL & ABS to turn on in the gauge cluster so I knew the harness was good, but really misled my troubleshooting. I ended up replacing the L4 Position Switch, CDL Indicator Switch, Transfer Neutral Position Switch, and Center Diff Lock Control Relay.... and the actuator itself was the only thing that was "bad".

My CDL Actuator didn't pass the FSM tests, and applying voltage from the battery directly to pins 2 & 3 didn't cause it to move... So I ordered a new one too.


Removing the actuator really isn't that bad as long as you don't try and take shortcuts like I did.

Save yourself the trouble and put the rear axle on jack stands to get the rear tires a few inches in the air. Put the jack underneath the crossmember, loosen the six 14mm crossmember bolts enough lower the rear of the transfer case ~1", and you don't even need to remove the driveshafts. This will give you enough room to lay underneath a stock height truck while working above the actuator (it is cramped up there). I believe it is 5 electrical plugs on the harness plus the breather for the actuator itself.

The actuator is held in place by four 12mm bolts, and three of them are pretty easy to get to. The bolt closest to the front end centerline is a royal pain and the only one you have to work on blindly. I had to use a 1/4" ratchet since it was the only thing with a low enough profile to fit up there. I attempted to remove this one without lowering the crossmember first, and didn't realize that what I thought was the bolt breaking loose was actually my 12mm socket cracking, and I almost stripped the bolt. Doing so would've required removing the entire transfer case to fix and would've turned this 30 minute job into a huge affair. Breaking the seal and actually prying the actuator off was really the only difficult part of this - there was a small lip/protrusion on the frontend side that I was able to hit with a long flathead and hammer to knock it off.

There is a gearset in-between the top of the transfer case and actuator that might come out with the actuator, drop this back in if does. You can manually turn this by hand lock the CDL, which you will need to do before replacing the actuator. You can feel the ball detent when it is locked, and confirm it by trying to spin a tire if there is only one in the air (it won't move when locked).

Applying voltage to terminal 2 & 3 of the actuator while it was out of the truck still didn't cause the motor to spin. Since I already ordered a replacement, I decided to take mine apart and see what was wrong. A lot of people report old or dirty grease underneath the gear cover clogging it up but mine seemed flawless.

I removed the cap (idk what its actually called) that houses the armature and I guess this is where my issue was. Be careful doing this as the brushes in here are spring loaded and the springs might shoot out if you remove the motor and shaft too quickly. A couple of my windings were black and a bit corroded plus It looked like the brushes either corroded or fused to the commutator bars, because there was some crud on the commutator bars themselves. I hit the commutator bars with a wire wheel to clean it up, put it all back together and lo and behold, it works! tested it with a 9V battery first, and then plugged it into the harness underneath the truck and could hear the actuator working.

The bad news is that after all this time, money, and frustration it would've been a 30 minute job + 10 seconds with a wire wheel to fix my issues. On the bright side, I now have spare parts for everything electrical related to the CDL and since they're all becoming increasingly expensive and harder to find, I'll be prepared when something actually breaks. Once I regain access to my Flickr account I will update this post again with pictures.
 
Last edited:
Joined
Dec 8, 2016
Messages
17
Location
Columbus, OH
Part numbers I used:

  • L4 Position Switch (Beck Arnley 201-1788 Back Up Lamp Switch)
  • CDL Indicator Switch (Beck Arnley 201-1788 Back Up Lamp Switch)
  • Transfer Neutral Position Switch (84222-60081)
  • Center Diff Lock Control Relay (89531-60010)
  • Center Diff Lock Actuator (36410-60050)
 
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