100: Diff lock in Hi? (1 Viewer)

e9999

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Hi yall:
just went for a test drive with a '99.
The rear diff lock was engaging in low but apparently not in Hi (kept flashing), IIRC regardless of whether the center diff was locked or not. (Probably a Mall cruiser, had to coerce the rear lock in low too, by going in reverse the first time but after that it seemed OK...)
Is it supposed to not lock in Hi?
thanks
Eric
 
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Eric

The "Center Diff Lock" mechanism / computer must recognize that the transfer case is in low range, before it will let the electric lockers engage.

This is the same on the 80 series

Joe
 
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Eric,
The 80 diff lock ECU limits the axle diff lock engagement speed to < 5MPH (or close)

With the CDL, we can lock the center diff at any speed. FYI, you do NOT want to drive with locked axles, front or rear, at speeds higher than 10-15MPH. Definitely not on the front.

-B-
 

e9999

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Hi BW:
(this is a 100 btw, modern technology and all that, you know... <G> j/k)

I turned the switch on while stopped and then went on (low speed) to see if it would engage in Hi but it would not. I did not try to turn it on while moving, if that makes any difference

thx
Eric
 
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Eric,
Joe's answer covered that... I was just giving you additional information. As he said, stock 80/100's have to be in Low range before they will lock the center diff. The rear (and front on 80s) will not lock until the center diff locks.
-B-
 

e9999

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B.
this is getting confusing. The center diff now?
I was able to lock the center diff with the switch while in Hi IIRC...! Well, at least the CDL light was on steady in Hi. Am I imagining things?
Eric
 
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Eric,
Having never been in a 100 series, I am not qualified to answer your questions. I *assumed* the 100's center diff worked like the stock 80 center diff. I described the way an 80 works.
-B-
 

e9999

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thanks B, I appreciate the info anyway.

OK, anybody there with a 98 or 99 100? Is one supposed to be able to lock the rear diff while the Tcase is in HI?

thanks
Eric
 
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Eric

The 100 series crusier has a transfercase, which provides both hi & low range 4wd.
Inside this transfer case beside the hi / low range gears, is a "differential", very similar to the differentials located in the front / rear axles.

The differential in the transfer case works in a very similar fashion as the differentials in the axles.
A "Differential" allows one wheel to rotate / spin at a different rate then the opposing wheel, i.e. this allows you to drive around a corner, as the outside wheel is traveling farther [the side gear attached to the axle to the wheel is turning faster] then the inner wheel.

Ok, now in an "All Wheel Drive" vehicle with each wheel gripping the road, which means that each wheel / axle / side gear is rotating at different speeds. The different speed of each wheel creates "gear wind-up" [similar to twisting a rope], which is constantly increasing the wind-up, then releasing the wind-up, constantly repeating. So, the transfer case in the 100 or 80 series has a "differential" inside the case, which is called the "Center Diff" due to its rough location in the middle of the drivetrain.

So, as the wind-up is created, the "Center Diff" allows the wheels [think back along the connection points, i.e. wheel, axle, side gear, ring / pinion, driveshaft, transfercase gears, which is coming from all four corners of your cruiser] to rotate freely and not create the "binding / wind-up". The "Center Differential" is slightly different then the axle differentials, as it utilizes friction to create all wheel drive / power transfer.

Ok, Now the "Center Differential" came from the factory with a computer controlled, electric motor, which locks the "Center Differential" when low range is engaged. Locking a "Center Differential" means that one side rotates at the same time / speed as the other side. So, a Locked "Center Differential" allows direct / even powertransfer to both the front & rear axle / wheels. So when shifting into low range, and computer locked center diff, you have true 4WD Low range

So, when an axle is locked both tires / wheels must turn at the same time, and going around corners is very hard on the tires / drivetrain. This also makes the vehicle want to track in a straight line and difficult to turn [both tires are turning at the same time]. This is the same concern with a locked center differential, considered the wind-up if all 4 tires had awesome traction, and the differential in the transfer case was locked / unable to rotate. This is the reason shouldn't drive on hard surfaces in 4wd drive hi or low.

To prevent this Toyota only locks the center differential in low range. This means that from the factory, you have AWD [almost 4WD in the cruiser / more then passenger car AWD] and 4WD Low Range in the United States. Now in other countries they have the ability to lock the Center Differential in high range, which provides 2 more traction options, 4WD Hi & AWD Low Range.

We can buy the "Center Differential Lock Switch" and install it into our 80's / 100's [to 99] to also get these additional traction features.

Finally, the electric lockers [front / rear] in 80's and [rear] in the 100's will only ENGAGE if the CENTER DIFFERENTIAL is also LOCKED. So, as mentioned above, when in "HIGH RANGE" the Center Differential is not LOCKED, so the electric lockers WILL / CANNOT engage / lock.

Hopefully this answered your questions and provides some insight. Please search for the 80's cool webpage, and there is a great, simple article on all types of four wheel drive systems.

Joe

Been reviewing the electric schematics to find a simple modification to get lockers in AWD.........
 

e9999

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Hi Joe:
thanks kindly for the info. I think I know what a diff is, actually, but anything helps. There is also the VC, btw, to make it even more interesting.
I sure don't mean to sound argumentative, but I'm not sure that we are talking about the same thing, though. I am talking about a 100.
All the 99s I have seen so far, that's 4 or 5, had a center diff lock switch, apparently from the factory since all were mall cruisers. And all of them also had the rear diff lock.
Also, IIRC, all the ones I test drove on dirt could run with the CDL engaged (per the light being steady at least) in High range. I could be wrong about this -what with the excitement of the moment and all- but then I am in worse shape than I think. (Glad that the brain is the first thing to go though...)
Oh, also, on the one I tried today, I think I could even lock the rear diff in low range without the CDL being engaged - but I'm not 100% positive about this.
(And besides the lights coming on and all, I could also hear the engagement or disengagement sounds...)
What am I missing?
Eric
 
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11Nov2003 (UTC -7)

[quote author=Warthog link=board=2;threadid=7428;start=msg61976#msg61976 date=1068607563]
Eric

The "Center Diff Lock" mechanism / computer must recognize that the transfer case is in low range, before it will let the electric lockers engage.

This is the same on the 80 series

Joe
[/quote]

Hate to burst your presumptions gents, but the UZJ-100 with the HF2A transfer case (i.e. with Toyota USA center diff lock switch) will engage in either 4Hi or 4Lo. A pretty useful trick actually, when running fast in slush-snow or on loose gravel roads.

But the FZJ-80 with the the HF2AV, only engages the CDL when in 4Lo (i.e. it doesn't have Toyota USA CDL switch) --however, you can later install a CDL switch as a trick mod to activate the CDL whether in 4Hi or 4Lo.

IIRC, the earlier FJ-80 with the HF2A transfer case also had the CDL from Toyota USA, like the UZJ-100.

However, the fr/rr diff lockers will only engage when in 4Lo.
 

e9999

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OK Drexx, good to know I did not hallucinate about the CDL. Was getting worried... (What's with this 80centricity anyway? Very unPC, if you ask me... <G>)

And then both you and Matt agree that the rear diff can only lock in Lo. Good.

One last question out of curiosity. Am I remembering correctly that I was able to lock the Rear diff in Lo without the CDL engaged?

thanks
Eric
 

landtank

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WELL on my 80 the lockers only engage if the center is locked. With the switch I can lock the center in hi range and there for also lock the front and rear in hi range.

At least I think so ::). I'll recheck later!
 
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Hey Eric,

I don't know where all our 100 guys have gone too but we have them.

All the answers of the 80 guys won't help you much. :slap:

So come out your 100 owners. Don't hide and answer that simple question :D

I hope that will help now :cheers:

Mike
 
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[quote author=e9999 link=board=2;threadid=7428;start=msg62057#msg62057 date=1068617128]
B.
this is getting confusing. The center diff now?
I was able to lock the center diff with the switch while in Hi IIRC...! Well, at least the CDL light was on steady in Hi. Am I imagining things?
Eric

[/quote]

No. I believe friends' '01 and '03 100s have a lockable center in hi or lo, so you could say the center diff lock switch is "standard." :) I've never heard of a toyota factory rear diff being able to lock in hi-mode while stock. There's usually a wire to the [rear] diff lock ECU that, if you cut and tie it either ground or hi (can't remember), you can lock in lo or high (someone documented this for the 3rd gen 4runner). Trick is figuring out which wire this is for the 100. You need to find the locker ECU and start measuring w/ a voltmeter in different modes.
 
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My 99 with a rear diff lock (use it all the time) engages only in low range. Now, in an unmodified state, when the T case is in low range the CDL is engaged as well. I my case, I disconnected this interlock so I can run in low range without the CDL locked.

Also, the rear diff lock does not engage instantly. In most cases it takes some rotational differential between the left and right wheel (easy on the gas then) to engage, but then again I am not telling you something you don’t know. ;)
 
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Eric

98/99 100 series doesn't have a Viscous Coupling. When then installed the V8 they removed the VC in the transfer case. Later model 80's had the VC to help stranded soccer moms get out of the parking lot puddles.

The 100 series has from the factory a "Center Diff Switch", which when depressed provides 4WD hi & 4WD Low. This is where I wasn't fairly clear - us 80 owners had to puchase this switch to have the same features of the 100 series.

Both the 100 & 80 series electric lockers will only engage when the CDL switch is engaged like others have mentioned.

Other then additional luxury admentities, V8, and IFS there really isn't much of a difference between the two landcruisers models.

Funny Story, at a local Lexus dealer the detail guys are always accidently engaging the CDL switch during detailing. This leads to numerous small dents / dings / scraps from the detail drivers since its a pain to drive in 4Hi on asphalt [detailer and / or owner], costing additional repair time / costs incurred by the dealer. They are constantly reviewing this subject in their training.

I also love the 100 series, and plan on getting one soon to complete a front axle swap creating a 105 series!, Dreaming again!

Joe
 
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[quote author=Warthog link=board=2;threadid=7428;start=msg62244#msg62244 date=1068662749]
Eric

Funny Story, at a local Lexus dealer the detail guys are always accidently engaging the CDL switch during detailing. This leads to numerous small dents / dings / scraps from the detail drivers since its a pain to drive in 4Hi on asphalt [detailer and / or owner], costing additional repair time / costs incurred by the dealer. They are constantly reviewing this subject in their training.

I also love the 100 series, and plan on getting one soon to complete a front axle swap creating a 105 series!, Dreaming again!

Joe


[/quote]

How do they incur the additional dings/dents, by bumping into walls since they can't turn as easily? Wouldn't it be great if one could order a 100 and be able to check a list of boxes on the order form for the engine you want (I-6, V8, diesel, or TD), suspension options (live front axle or IFS, rear leafs or coils), locker options (f/r/center, rear/center, center only), A/C options (none, front only, front/rear), upholstry (leather, cloth), rear door (van or hatchback), wheels (split steel, 16"/17"/18" alloy), tranny (5spd manual, 5 spd auto, 4 spd auto), battery options (single, dual), alternator (standard, heavy duty), air filter (precleaner, cyclonic w/ precleaner, standard rectangular), etc. What a concept! Toyota, are you reading this?
 

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