After learning that I should have been using my CDL monthly, I decided to see if it would even engage. I drove my '97 SD into a field adjacent to my apartment and shifted from H to N, it seemed to stick a bit before it shifted but the CDL has lain dormnat for over a year. Then from N to L. This seemed to work andI drove slow for a bit. I then shifted to Diff lock and drove a bit more. The only issue I had was the theCDL/diff locklight did not come on. After shifting back into normal driving mode, I headed back into the parking lot of my complex and a shrill whining sound started up. I parked the disco and let it sit, shifted into Neutral then moved the CDL shifter further down to H, though it seemed to be in H already. I parked by my apt then put it into Neutral in order to fiddle with the CDL and see if the CDL light would come on. I got no light but the whine did come back once I shifted to N (on the CDL) and would not stop untilI shifted back to H (what seemed to be farther south thanH, really). I don't go offroad or tow that much, in S. Louisiana I would need a snokel set-up to offroad inmost places, but I would like to have the CDL ready as an option. Any clue if this is functioning normally?

 

I don't think you have it all the way in gear, or your transfer case is low.

You don't have to drive it just shift the transfer case to keep the shifter from locking up.

 

You were all the way in to gear or your would have had a warning indicator come on.
Is it only whinning in low range? Have you checked your t/case fluid, when was the last time you actually serviced this truck?

 

My diff lock light didnt work at first either, after a couple of uses it started to work, no problems now.
Have your drive line serviced, most quick lubes will do both diffs and t-case for around $60, I have mine done every spring, but if your t-case is low on fluid it will make noise. If it wasnt fully engaged/dis-engaged it will make noise too.
Get it serviced and then use the CDL once a week for the next 4 weeks to get it loosened back up and working again. You can do it in your parking lot, but go through each gear just like you did, drive it 20 feet then change to a different gear and drive another 20 ft,that is what I do, but I also off-road about once a month too.

 

Mike, whining in N and Low, haven't checked t/case fluid and by "service" do you mean tune-up or fluid flushes?

 

At 114K, you should have replaced all your fluids, including the t/case.
I am concerned when you say it whines in Neutral, are you talking about when the tranny or t/case is in Neutral?

 

It was a eletronic whine when the CDL shifter was in Neutral, I thought it was in H but I pulled it farther towards me (and finally into H it seems) and it stopped. I've driven it today with no issues.

Is may be a stupid question but you should I go to have my fluids replaced. I should follow your 60k list of fluids or is there a 100k one as well? Is there a chain out there or should I go to an indie mech? I've been shopping for a good mechanic but I haven't found one in my area yet, even put up a post for suggestions on this forum last week. I'm gonna get my oil changed soon and I can ask someone there (I'd change it myself but it's kinda awkward to do in the apts I live at.

 

You were probally hearing the warning buzzer, when the t-case is in neutral and you put the transmission into park it wont hold the trk so there is a buzzer to warn you that something isint koser and being old the buzzer doesnt sound like a buzzer anymore.
You can have your diff's and t-case serviced at the quick lube, just like I said before.

 

I agree, you may be hearing a failing warning bell. As for the service, if you want to go spend upwards of $500 plus, sure let a shop do it, other wise I will walk you thru it. It is better for you to do it so you know what makes your truck tick.

 

If all you are doing is replacing fluids a quick lube can do it when you get your oil changed.