Weird coincidence, or somehow related?

I have a 2003 4.8L Styleside.

The few days ago I needed to use 4WD. It engaged, but then would not disengage. The 4HI indicator just flashed, and I could feel the front tires binding when turning at low speed. At the same time, my brake light was on due to low brake fluid level (it's got a minor leak I haven't tracked down yet).

I drove it that way for a couple days hoping it would unlock, but no avail.

When I added brake fluid and started the truck both lights when out and 4WD disengaged.

Was this a coincidence, or does the 4WD somehow rely on brake fluid???

 

It's all tied into wheel speed sensors. I had an issue a couple years back where we had a very wet slushy snow, I put it in 4wd, it worked fine for a little bit, but then my abs, and brake lights came on along with some other lights. 4wd would not disengage, I had to make a 5 point turn to get around a cul de sac because it was binding up so much. A big chunk of snow fell off and the lights went off and 4wd disengaged. Found out through some research that the wheel speed sensor got gummed up with the snow and that prevented the 4wd from disengaging and also turned on the brake lights. Would not be surprised if the brake issues caused the 4wd to stay on too.

 

Keep in mind 2.5 gen and 1st gen are a bit different. Not sure all the fancy stuff existed yet. My 01 has no ABS and therefore no wheel speed sensors at all. Sounds like OP had an actuator issue but hard to say for sure.
Always best to use 4wd once a month or so to make sure nothing gets locked up.

 

I swear I heard someone else on the 1GT forum mention WSS causing issues w/4WD. I'm fairly certain that's a thing...

 

I've read a lot about it on 2nd/2.5 gen trucks never heard about it on 1st but I could be wrong.

@bumpty does your truck have ABS?

 

Who knows how to bypass the ADD if someone gets stuck in 4hi? Just unplug it?

 

I didn't realize I was responding in the 1st gen forum, but my dad had a 2000 and when he had issues with his ABS, it would throw codes and turn on lights with the 4wd as well so I assume at least some of them have the wheel speed sensors.

 

Sorry for the lengthy delay. Yes, my truck has ABS. I know for certain because I just replaced my rear axle assembly and it was a PITA to find a nice replacement with 4WD, ABS, 3.91, non-locking. Having owned Jeeps, it's very strange to me that there are physical differences, aside from gear ratio, between 2WD & 4WD and locking vs non-locking.

Snow season is arriving soon, so I guess I'll get to see if this happens again. In the meantime, a bottle of brake fluid has been added to the bed box.