1996 D1 center diff lock light

[Blueboy]

Always like to make sure it is easy to engage low range and exercised it when out on a easy trail. Engaged diff lock and the light didn’t come on.
This morning made sure it was engaging by following a tip from a few years back on here:
“Finally, an easy way to test your center diff lock is to chock the vehicle in neutral with parking brake released and jack one wheel (any one, doesn't matter) off the ground. With center diff unlocked you can turn it, with center diff locked you can't. The engagement is a dog clutch and it is spring loaded both ways on the shaft so when you move the lever the light may not come on if the alignment is not right but turning the wheel any amount and it will pop in. This explains why the light may or may not come on or go off immediately when you move the lever. I performed this test and mine is working exactly as it is supposed to.”

Did this on the front wheel and confirmed yes it was engaging yet no light came on. Removed the jack and with the ignition on in park engaged diff lock and the light comes on. Tried it again and no light yet you can hear it engaging.

Do I just not worry about the light? Or is something else happening?

 

[Jimmy]

Check the function of the switch on the case would be my guess as to what to do next.

 

[MonLand]

On my 90 the switch disintegrated. Technically, you can replace the switch without removing anything else. It’s a real pain as access is restricted.
i replace it, rebuilt (two part epoxy is the $h17!) the old switch….. and never adjusted the new switch… so…. Still no light for me!

 

[Blueboy]

Check the function of the switch on the case would be my guess as to what to do next.

Thx.

 

[Blueboy]

On my 90 the switch disintegrated. Technically, you can replace the switch without removing anything else. It’s a real pain as access is restricted.
i replace it, rebuilt (two part epoxy is the $h17!) the old switch….. and never adjusted the new switch… so…. Still no light for me!

Yea, I’m thinking that as long as the diff lock is engaging I’ll remember to disengage it.
Next time on a lift I’ll have it looked at. Just weird the light went on and then trying to confirm it didn’t.

 

[discostew]

I find that a long decel from about 35 mph usually disengages the thing then the light goes off.

 

[Blueboy]

I find that a long decel from about 35 mph usually disengages the thing then the light goes off.

My situation is I know the diff lock is engaged yet the light sometimes is on and sometimes off. If it is on and when disengaged it takes a short distance for the light to go off. After 26 years guessing there is an electrical issue with the switch that triggers the light like Jimmy mentioned. The light is just a nice feeling for confirming when engaged and then disengaged.

 

[Flyfish]

My situation is I know the diff lock is engaged yet the light sometimes is on and sometimes off. If it is on and when disengaged it takes a short distance for the light to go off. After 26 years guessing there is an electrical issue with the switch that triggers the light like Jimmy mentioned. The light is just a nice feeling for confirming when engaged and then disengaged.

The light stays on for a short distance because the gears have to unwind and disengage after there’s no stress in the driveline.

If you lock/unlock the tcase when the truck is rolling in neutral slowly, it happens much quicker.

 

[discostew]

My situation is I know the diff lock is engaged yet the light sometimes is on and sometimes off.

I know. Everyone has told you the correct info. Check that circuit, but probably the switch.

 

[Blueboy]

I know. Everyone has told you the correct info. Check that circuit, but probably the switch.

Yes, thinking the same after the responses.

 

[Blueboy]

If you lock/unlock the tcase when the truck is rolling in neutral slowly, it happens much quicker.

Will give that a try before messing with the switch.

 

[Flyfish]

Will give that a try before messing with the switch.

 

[Blueboy]

View attachment 63426

My light is intermittent going on when selecting Diff Lock. I’m going to try your neutral concept later today as well. Hoping it is not an electrical issue with the switch yet after 26 years wouldn’t surprise me.

 

[Flyfish]

My light is intermittent going on when selecting Diff Lock. I’m going to try your neutral concept later today as well. Hoping it is not an electrical issue with the switch yet after 26 years wouldn’t surprise me.

Possibly your cdl/linkage is a little sticky so sometimes you’re right on the edge of triggering the switch.

It shifts/engages completely much easier if you’re rolling.

 

[Blueboy]

Possibly your cdl/linkage is a little sticky so sometimes you’re right on the edge of triggering the switch.

It shifts/engages completely much easier if you’re rolling.

Tried again this afternoon. Low range, rolling in N, and engage cdl. Light immediately comes on. So thinking not the switch and possibly the linkage as you mentioned since drive on dirt roads almost every day. It shifts very easily from High to Low yet I don’t use cdl that often. How easy is it to access the linkage to lube it?

 

[WaltNYC]

this may help

 

[Blueboy]

this may help

Surprised it works at all!!

 

[Flyfish]

Tried again this afternoon. Low range, rolling in N, and engage cdl. Light immediately comes on. So thinking not the switch and possibly the linkage as you mentioned since drive on dirt roads almost every day. It shifts very easily from High to Low yet I don’t use cdl that often. How easy is it to access the linkage to lube it?

Sounds like it’s working properly when you lock/unlock while rolling. The gears just mesh/sync much easier when rolling and you’re not fighting the gears to get it fully shifted. I would do that several more times which will help with any stickiness. Hopefully that solves the problem.

 

[Blueboy]

Sounds like it’s working properly when you lock/unlock while rolling. The gears just mesh/sync much easier when rolling and you’re not fighting the gears to get it fully shifted. I would do that several more times which will help with any stickiness. Hopefully that solves the problem.

Thinking the same and plan on engaging the CDL more frequently. Just nice to see that light come on and off!

 

[Flyfish]

Thinking the same and plan on engaging the CDL more frequently. Just nice to see that light come on and off!

Glad that took care of the issue.

Typically there is a decal by the cdl lever that illustrates N & then shift while rolling between 0 to 5mph.