Diff lock light came on

[kcabpilot]

Truck is a 2001 D2. A few weeks back I hooked up the diff lock by installing a lever off a D1. Everything was working fine, I even took it on a trip up to the mountains and drove in the snow a bit. Today as I was driving to work on the freeway doing about 65 or 70 in the rain the diff lock light came on by itself. I pulled off and shifted the lever back and forth and it went out. Back on the highway and it came back on. I couldn't get it to go out again until I exited and made a turn.

I know the thing sat unused for 14 years but to be honest I'm not really sure how it works. I mean what actually happens when you turn the little spigot 45 degrees?

 

[JohnB]

It locks the transfer case so both driveline front and rear spin together locked. If your transfer case is locked and you are on a surface like a street and you turn a corner you will feel a kind of skipping sensation.
I know my D2 that light sometimes takes a few seconds to go out but I've never had it go one for no reason. I would suspect that the switch is malfunctioning.

 

[kcabpilot]

Yea I know it locks the transfer case split. What I mean is how does it do that? Is there a hydraulic valve that the spigot turns on and off or is there a mechanical linkage of some sort. I know the spigot isn't very big and it doesn't turn much and there's virtually no resistance when turning it. I noticed that the diff lock light doesn't go on and off immediately when moving the lever but usually after driving a few feet it switches.

 

[stu454]

There's a youtube video showing how it works.

 

[number9]

Yea I know it locks the transfer case split. What I mean is how does it do that?

You just have a indication issue? If so indication switch is internal I believe or the fault is likely in the wiring outside the box. Should be able to find most of what's needed to troubleshoot in the Rave manuals.

......

 

[discostew]

The switch at the top of the t case with 2 spade terminals on it is the switch your looking for. They get stuck sometimes. Or something could be shorted. I would think if it was really locked and your driving on dry roads you would have posted about crow hop knocking fillings out of your teeth

 

[kcabpilot]

The light came on again last night on the way home after about 20 miles and being on the freeway I didn't notice anything different and didn't want to mess with the lever at 70 mph so drove another 40 miles with the light on. When I got off the freeway I started messing around with the shifter and eventually got it to where it seemed to work right. I could get it to come on then go off when I selected lock and unlock but at times it would take a few seconds.

So I did the Google search, watched the videos, read a bunch of forum posts and looked in the Rave manual. From the video I can see that it is definitely a mechanical dog-clutch type engagement that activates a mechanical warning light switch. So you would think that when you go to the lock position the light should come on immediately but the switch sends the signal to the SLABS ECU and I guess it decides if or when to actually turn the light on and off so who knows what goes on in there.

As for the Rave manual, it was more confusing than anything else as it refers to pre 03 and post 03 models as being different in that the pre 03 has only one warning light switch illuminating a red diff lock light whereas the post 03 has two warning light switches illuminating an amber light. It also says that the diff lock in the pre 03 models was only left on there so the vehicle could be tested on a rolling road with front driveshaft removed and that engagement will disable the ETC. So there are a few inaccuracies there as I've engaged the diff lock and have not gotten any warning lights for ABS, traction control or hill descent.

I'm pretty sure then that what I have is an indication issue, probably due to the fact that the whole thing sat unused for fourteen years so for now I'm just going to keep engaging and disengaging it in the hopes that it will start behaving. I really don't feel like ripping the console out again right now but if I do at least I put it back together with screws instead of rivets.

 

[JohnB]

Yep I'd pull the switch and check that.
Rover left the nipple off the 03's and Rave does seem to confuse the entire reason for the diff lock in general.

 

[kcabpilot]

I drove another 120 miles in the rain yesterday and had no trouble so exercising it seems to have cured the problem for now.

When I was in there doing the conversion I wanted to pull the switch and the spigot to clean and lube everything but it was freezing cold out (well, by California standards, about 50) and it's a bit tight and uncomfortable reaching down there through the tunnel while standing outside and leaning over the seat. I got a socket with long extension onto one of the three bolts on the plate but it didn't want to budge and I could see myself snapping one off or stripping it so I left it alone. You'd have to get a stubby open end down there to get the switch out. It would have been a challenging task.

One thing I might add for anyone else thinking about doing this (talking about using a D1 lever) you are going to get some transfer case whine into the cabin because the lever is now mounted directly onto the case. I can see why Rover changed to the cable operated system as it's completely isolated and silent. It's not really that bad but noticeable, especially at around 65 mph in my case. Not bad at 70 which is what I usually cruise at but definitely there at 65.

Problem was, I couldn't find a used lever from an '04 and the kits are well, pretty expensive, like six hundred bucks.

Still, I'm glad I did it.

 

[kcabpilot]

Chapter 2

I have to reopen this thread due to some still lingering questions and to do this I have to go back a bit to when I first hooked up the diff lock by installing a D1 transfer case shifter.

When I finished that job I drove down to the gas station and filled up. When I was pulling away from the pump I heard a loud BANG from underneath the truck. I thought I had hit something so I stopped, got out and didn't see anything unusual at all. Afterwards the truck drove fine and I couldn't figure out what the heck that could have been? I drove it regularly over the following two weeks. I used it to commute to work because of nasty weather and I even took a trip up to the mountains to play in the snow. Everything seemed fine.

But after the diff lock light issue I started to hear a kind of groan that gradually turned into a rumble and then a vibration. It was only there when accelerating or going up a hill so I crawled under to take a look. Nothing obvious but the front drive shaft seemed to have a bit of play and it's been quite awhile since the last time I rebuilt it. I ordered the new parts and took both front and rear drive shafts to the driveline shop. Turns out the centering cup on the aft flange of the Hookes joint was busted. I'm pretty sure that's what the big BANG was all about. I don't know exactly what it was but my theory is that while working on the tunnel above something got in there. Maybe a stray rivet shank or dropped screw. I think I did drop a nut for the diff lock shaft and never found it but can't recall for sure.

Anyway, the driveline shop had a serviceable replacement, got everything back together and as I was reinstalling it all I came across another puzzle which is the reason for this post.

With all of the wheels on the ground and both driveshafts ready to go in I was able to rotate the front shaft to align the flanges but when trying to install the rear driveshaft I couldn't turn it. I had to lift one of the rear wheels off the ground so I could turn the rear diff flange to match.

Soi it seems to me that my center diff is locked even though it's not sup[posed to be. Or maybe I'm just not understanding how the whole thing works?

Sorry for the long post but I want to get to the bottom of this.

BTW - post work test drive went fine, very smooth no rumbles or vibrations up to 80+ mph.

 

[mbrummal]

Was the transmission still in park when you tried to turn the rear output flange? Was the parking break engaged?

 

[kcabpilot]

Parking brake was off. Transmission was in Park but I didn't think it mattered since I was able to turn the front driveshaft as long as the rear was disconnected but could not turn the rear with front connected. In other words the front and rear outputs of the transfer case could not be turned independently.

 

[JohnB]

If trans is parked you can turn the front shaft if one of your front wheels is off the ground.
Pull your front shaft off and lock your diff. You should still be able to drive around. Unlock your diff with the front shaft out and you won't go anywhere.

 

[Devildog01]

Try applying a small piece of electrical tape over the diff lock light on the instrument cluster. Problem solved. Your welcome.

 

[kcabpilot]

If trans is parked you can turn the front shaft if one of your front wheels is off the ground.
Pull your front shaft off and lock your diff. You should still be able to drive around. Unlock your diff with the front shaft out and you won't go anywhere.

Well that's what I'm talking about. If center diff was not locked I should have been able to turn the rear shaft with the front one connected just like if you lift one wheel you can turn it even though the opposite one is still on the ground.

 

[mbrummal]

Chock the wheels, lift one wheel in the air and put the transmission or transfer case in neutral. If you can spin the wheel, the center diff is not locked.

 

[JohnB]

Well that's what I'm talking about. If center diff was not locked I should have been able to turn the rear shaft with the front one connected just like if you lift one wheel you can turn it even though the opposite one is still on the ground.

Yep as long as e-brake is off. Starting to think you must have installed the linkage to the diff wrong. If I remember you can do that.


Could be why you broke your front driveline since it was really bound up on dry pavement.


This may help
https://www.youtube.com/watch?v=3edP_cIkO50

 

[kcabpilot]

I did have to make some adjustments to the lever but here's how it ended up. With the lever full right the spigot tab points straight forward and is in the detent, With lever full left it rotates 45 degrees and the light comes on. You can see the Hookes joint right below and I'm pretty sure I must have dropped something in there during the work that caused the damage, maybe a washer or a nut. After the bang everything seemed fine, I even took a 300 mile trip up to the mountains. If the driveline had been winding up I'm sure it would have done more than just that one bang. The damage found during overhaul was a crack and small chunk missing from the centering cup of the aft flange pf the joint.

To add to that, after reinstalling both driveshafts I just did a 120 mile trip to work and back at 70 mph and no hint of complaints, everything is silky smooth. Diff lock light seems to be working correctly too, hasn't come on again since that one incident.

I'm thinking it's all working as it's supposed to but I'm still left scratching my head as to why I couldn't turn the rear shaft with the front one connected. Maybe I should add that the transfer case was in LO, don't know if that would make any difference.

 

[JohnB]

looks like you have it in nuetral

 

[kcabpilot]

I'm just talking about the lock/unlock spigot. I don't think I had the HI/LO linkage connected yet when that picture was taken.