Diff lock issue.

[BeaverBill]

hello all,

I wonder if any of you experienced folk can help me on an issue.

Got a 2003 H2 (75000 km's) that doesn't seem to want to unlock the back diff. We select 4 Hi unlock and the rear tyres seems to "skip", feels as it's breaking, hard to move upon semi to hard cornering.

What we've done so far:

...nothing really. Got the rear up on jack stands and changed fluids and filters (engine, tranny and rear diff.) as well as visually inspected the diff, taking off the cover. Liquid out of the diff was "old" with slight deposits but no metal. Looks in good order with only one mental note. (need to post a photo if anyone is really interested since I'm lost for words....a retaining hook on what seems to be a stud for the locking gear on the left side seems to be slightly bent down compared to the right side's retaining hook).

What we plan to do:

Change the transfer case fluids when we figure out how much the tranny will take (GM rep for Spain gave us 7 liters of ATF for the tranny but wonder if he included the transfer case as well as we didn't control how much of the ATF came out of the tranny....we don't have a shop manual aside from my protests ).

What we are scratching our heads over:

What is causing the rear diff lockup?!? How can we test it? With the rear on stands the wheels move in opposing directions when we spin one of them but if we try to spin them from the axel they want to spin the same way (therefore locked, I assume ) We couldn't spin the axel freely (taking into account that the tranny was in neutral, with the fluid drained, motor off and the front tyres on the ground) but the front wheels were on the ground. We gave the 4 wheel drive selector a go and observed no movement in the diff with the cover off but heard the transfer case working.

I've read that there are two possible causes, the actuator for the locking clutch at the transfer case, or the TCCM (transfer case control module). The most common problem is said to be in the actuator. The TCCM I've somewhat ruled it out as it seems to be sending the orders upon pressing the selection with no erratic behavior, but leaves me to ask if I should consider that it is not sending the info to unlock the diff? Doesn't seem very likely... does it?

Moving onto the actuator, what role does it have to play? Does it send information to the rear axel to lock or unlock. I still don't understand how the transfer case has anything to do with an unlocking diff. I can only add that when I selected 4 low (locked) it I got the same sort of mannerisms on the front as well as the back when moving on pavement, full steering lock.

I'm having problems mentally connecting the transfer case to diff lock, any insight on the missing puzzle piece would be appreciated.

If I unplug the connector on the diff does the elocker unlock or does it "fail" in a locked state? Can I tell if unplugging connector on the diff has made a difference with the vehicle up in the air in its current state or do I really need to have the vehicle running to see if it has any effect?

Once again, thanks to anyone before hand in providing any insight.

P.S. obd2 seems to have power as my bluetooth antennae lights up but the software doesn't hook up so I can't read any fault codes. Also....does the obd2 plug (vehicle side) only come with 4 wires connecting into it?! Seems a bit strange...?

 

[3Hummers]

Have you tried backing the truck up in reverse for a way? Sometimes the t case gets bound up and that will help unwind it.

 

[BeaverBill]

3Hummers, when you say backing up a fair distance should I assume backing up at some sort of speed and engine braking? This is the second time I heard the trick. I have backed up the truck a crawl, a good 30+ odd feet into it's current position inside a warehouse, but with no determination, never really thinking the process through....maybe I should have tried putting a bit more welly into it?

 

[3Hummers]

No need to do more than back up at a modest speed, 5mph should do. I have seen people have to back up as much as 100' but usually 25-30' will do it.

 

[Scarsman]

If they spin opposite directions when you grab one and spin it, then it is unlocked. If the diff is locked then there is no way you can just spin one wheel. They must both go the same way when locked.

I think your problem is your transfer case is stuck in 4 hi. Could be your encoder motor. Not an uncommon problem.

 

[BeaverBill]

Thanks 3Hummers...unfortunately, we've got it up in the air with the rear diff cover off and we've booked a mechanic to come around to give us an opinion, so until it's on the ground I won't be giving it a real go with what you are suggesting.

Scarsman.... that's what I had assumed after searching around for answers, but as mentioned in my long winded thread starter, if we spin an individual wheel the other goes opposite, but if we go by the drive shaft we have the both rotating the same direction. Yesterday we lifted the front end off the ground started the beast up and ran through all the gears (transfer case and tranny) while visually inspecting the open diff. There was no visual movement within the diff with the gears upon selecting the diff locker option, but in youtube videos of a diff (with their cover off as well) in other 4x4's it shows the elocker actually moving and locking into place. We had also removed the transfer case actuator and went through all the transfer case gears with a visual inspection of its operation. The actuator did all 3 positions (High unlocked, high locked and low locked) with nothing strange noted with its operation. All we need to do for maintenance is change the transfer case oil, front diff oil and finish off the rear. We'll be getting the mechanic also to hook up a volt meter to see if the rear elocker is actually getting a signal as unfortunately I never had gotten my head around the very simple task of working a volt meter and feel the need to have someone hold my hand with this lesson.

After all the inspection we've done I still seem to come to the inexperienced conclusion that the rear diff elocker is jammed up. I guess the mechanic will tell us where the problem lies in the end.

 

[Scarsman]

With both wheels of the ground turning the drive shaft will turn both wheels the same direction. That is normal. Have you tried holding one wheel still while you turn the drive shaft? I bet you can still turn the shaft and spin the one free wheel.

On the e-locker there is not really much movement to see on the out side. And the locker will only engage in low range. I still think your transfer case is staying a full time 4x4 mode. When you were driving it, did it go in and out of low range?

 

[BeaverBill]

Hey Scarsman, thank you greatly for your interest. The mechanic came over, and he's taken a look over it but i had to go half way through his visit, so until Monday I won't be able to get a 100% idea of what is going on and have to rely on second hand info from my brother in law.

While I was there the mechanic (my uncle, ex-Jaguar and fully experienced mechanic...he even did some rig racing in his day) went over "the basics" for us; we explained our observations and he explained his trouble shooting methods, he seemed to be on the same track as yourself, and he was betting on the transfer case, just as yourself, even if he didn't say it out loud, mentioning he was "80% sure"....none the less, he went about eliminating the group components. The theory behind the transfer case, according to his experience, is that there is play with the drive chain that groups the front with the rear within the case , therefore one group moves before the other, computer interprets that there is lack of traction , therefore actuates the traction control which in reality is an actuation of the brakes. (as traction control runs off of the ABS system)....that was his first impression.

None the less, they took a closer look at the elocker (on the rear diff, open, left hand side) (I was not there) and pried one of the plates of elocker from the main pinion gear, finding that a "c ring retainer had been chewed up into metal filings". They had hooked up the battery to the diff locker tested the actuating mechanism and there was movement upon locking (after prying it apart) between the plate and magnet / locking mechanism...... this is what I understand from word of mouth. If I was there I would have taken a video but it seems I have Monday to do the same as the mechanic will be coming back and, I believe, we will be taking apart the diff or investigating the transfer case (or both) or troubleshooting another issue...none the less the mechanic will be there Monday for me to grill him and we need to buckle down with or without him to take apart part of the rear diff to fix the retaining ring problem .... shame I couldn't be there for "4x4 101" till the end, as it's all very fascinating stuff.

 

[BeaverBill]

I still think your transfer case is staying a full time 4x4 mode. When you were driving it, did it go in and out of low range?

No, it didn't go in and out of low range while driving, it showed correctly on the selector (in cabin) and was consistent.

 

[Scarsman]

Any update on this? Curious to see what you find.

 

[BeaverBill]

Hello Scarsman!

We finally got to the issue (we think...we haven't tested it on the road). My mechanic's first impressions "seemed" to have been wrong but, as you know, it's a matter of elimination. He came by with his volt meter and some "ideas" to hook up the diff lock so it would operate without the use of the vehicle's electrical system (a current converter from a computer) with no avail (we couldn't plug the converter in properly to the plugs(DOH!!) )...... but upon further investigation (manually prying the e-locker into place with a screwdriver) he found a c-clip retainer had worked its way loose off the e-locker (outer left hand side, inbetween the axel bearing left hand side and e-locker)). It's a magnetized system and there are no visible working parts (from afar), it's internal, and its actuation is quite subtle. I wish I had taken pictures (ooops) but I had taken a rushed video of its operation. Unfortunately, the video will serve no one but myself as reference, as the video turned out crap.

All I can say is that upon idle (vehicle up in the air/ wheels off the ground, engine on, idle, in neutral) with the e-locker engaged (4 low), both wheels spin but when disengaged only the rear left hand side spins. There's a audible sound when engaging and disengaging, diff lock light within the cabin showed correct (minimal flashing when actuated). We had to play around with the wheels, at times, for it to lock up , but we are assuming we've got it "solved", until proven otherwise by a road test.

Sorry...wish I could provide more but I was working as a skivy / go-fer ( go fer this / go fer that) and the last thing that crossed my mind was documenting the operation., wish I could provide more.

I'll update again when we get it down and on the road. Thanks for your interest.

 

[BeaverBill]

...there seems to be a "loss in translation" from what I've been told before (the prior post) and what we've now encountered....such is "hear-say". (my previous disclaimer...uffff).

That said, there was no "c-ring retainer chewed up".

 

[Scarsman]

I was wondering about that! The c-clip would be inboard from the locker. So n is it fixed then, or still sorting out out? I feel your frustration! Those mystery problems get old real fast!

 

[BeaverBill]

OOOOpppsss.... the mechanic had it right from the start. :emb: We didn't waste our time by taking the cover off the diff as he did get the diff lock sorted out by seating the C-clip on the locker but, as a road test proved (done today), the problem wasn't fully fixed. We (our mechanic/ saint /uncle) took off the transfer case filler cap/nut off, got a camera in there and found a lot of play with the chain... he showed us the play by feel (with our pinky finger ), moving the front wheels back and forth, so the problem isn't "nipped in the bud" but we we are much closer to a solution...therefore this leads us to a transfer case removal and repair with a possible ABS sensor clean for good measure (as we are already neck deep into it) We've done a complete fluid change on the truck including brakes and radiator, and a ton of other work, so aside from the headache of doubt with the main problem, I'm well chuffed to be able to learn as much as we've done...but the battle is not over yet.

We are first looking into tackling the job of removal and then troubleshooting (after opening) the transfer case but I wonder if you could all be so kind as confirming the transfer case model. The model tag that's "supposed" to be attached to the transfer case but is non existent.

Can anyone confirm that the transfer case is model Borg Warner BW4484?

Can anyone suggest a supplier for rebuild parts?

I've found a few "rebuild kits" on the web but it's always nice to go through a "contact". If I go through the supplier over here they are literally going to take us for a walk and then piss on us for pricing The "GM supplier" wanted to charge us €12 for EACH interior panel fastener!!!! Needless to say we went EBAY and grabbed them for less that price for 15 fasteners from China, even then we feel that it's still over priced for plastic nubbins...such is life.

Also, any insight on the transfer case repair would be greatly appreciated. The mechanic mentioned that there could be a tensioner that has been worn and/ or has given way but I fail to see such a tensioner on the blown view of the transfer case (that's if I got the model right), therefore I ask, Where can the play be caused from?

The owner (brother in law) still has to be consulted if the repair will go through so we still don't know if we'll be diving into it, so hopefully he'll give us a go ahead and we get to get our hands dirty again as I'm quite enjoying the ride!

Thanks for reading, for the interest (Scarsman) and for the replies!

 

[BeaverBill]

"I was wondering about that! The c-clip would be inboard from the locker."

Nope, I think the unseated c-clip was "outboard", outerside of the e-locker, between the inner left main axel bearing and locker/ magneto mechanism . It was a mere retainer clip. I'll interrogate the mechanic again but I'm pretty sure I've got it right..... you got me thinking, so therefore I'll confirm.

 

[Scarsman]

Ok, my mistake, I was thinking of the axle c-clip. I understand now.

Yes, that is the correct model number for the transfer case. I can't really help you on a supply for parts for it. I've never had to do anything to mine. They do have a chain in them, and it is possible for the chain to stretch and cause slack, but not common that I'm aware of. They are fairly simple things though, as far as taking apart and all.

 

[Big2dabank]

I saw a rebuild kit for the tcase, I'll see if i can find it, because I will also be it soon, the chain in mine is loose and will slip when engaged in low lock under a lot of torque.


Sent from my iPhone using Tapatalk

 

[BeaverBill]

The chain is definitely loose and were are assuming that they must have really done a beating to it get it to that point (Quite possible worn to start with but what they did most definitely didn't help) ....the chassis bar (left side under the driver and rear passenger door, protecting the body ) had been scraped and "gouged" so it looks as if the driver had gotten stuck revved the hell out of it in an attempt to move it and then possibly had caught a sudden moment of grip to pop off the c clip.

We've gotten a green light to do the transfer case, so you all will probably see me here in the next few weeks asking questions.

I've found some rebuild kits on offer as well but none with chains....will update as I go along. Thanks for the input, boys!!

 

[CaseyS]

I'll put money that the shift fork in the transfer case is worn and still in 4 hi lock even though the indicator shows 4 hi street..

 

[BeaverBill]

Would that make the chain dance the way it does, CaseyS?