GCC Spec 80s with H4 Button…what does it do?

Joined
Dec 26, 2021
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I’m shopping around for an 80 while I’m stationed in Bahrain. Every one I’ve looked at so far (2x automatic, 1x manual) has an H4 button in where the CDL switch is normally located. I’ve asked for help in the Importing forum, but no help there. Hoping some of you GCC residents here can help me out.
What does that H4 button do? Are the GCC 80s not full-time 4WD, like the 60s? All three trucks I’ve seen, the H4 button doesn’t indicate anything at all on the instrument cluster, and I haven’t crawled under in the dirty street/sand parking lots during rainy season to grab the front driveshaft.
GCC residents, is there anything I need to keep an eye out for while I’m on the hunt?
 
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Yes I found both trucks on OLX. I used an interpreter (my Uber driver) who was extremely helpful finding trucks and actually negotiating price. He also runs a car rental place so he took both my vehicles and had them registered in Bahrain in my name. So helpful! Of course I had to pay him for his time. If you PM me I'll give you his contact info on Whatsapp.
 
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Actually, traditionally it's not.
4H was the term for a part time equipped cruisers when shifted to 4wd. This gives you a locked transfer (no centre diff) and equal drive to front and rear sides

CDL is used in an AWD full time transfer and locks the differential. Outcome is the same at that point, but the mechanics are different.

Some 60series had auto hubs with a 4H button on the dash. Some had manual hubs and the 4H button. I wasn't aware it was used in 80series. I don't think it was in any Australian model.

4H button engaged the hubs and 4wd in high range on the fly.
If you shift the transfer to 4Lo, it engages 4wd and hubs also

It'll be interesting to see if it's a re-named CDL, carryover 60S tech that you describe, or something else.
 
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My 70 series Prado (JDM) has the H4 button and power locking front hubs. H4 and hub lock have lights/indicators in the cluster. My understanding is that pressing H4 will engage the T-case, but without having the hubs locked prior you're still in 2WD. Maybe I'm wrong, or maybe it doesn't apply to the 80s.

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Dave 2000

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I too am not sure why the H4 button is there but just to clarify something. The typical 80 is 4 wheel drive but lift just one wheel and it will not move, if a VC is fitted it may try to drag the car off the jack but rarely is able, unless you have tried driving a VC equipped model with a propshaft disconnected it drives like a vehicle with a slipping clutch, eventually you would burn up the silicone fluid and then it jams and then when you fit the removed propshaft the vehicle will crab in corners.

Regards

Dave
 

SNLC

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Look at the front of the tcase. H4 button operates vacuum tcase, it engages 4wd via vacuum switching valves. If you look at the tcase front out put there is a vacuum actuator which is what the H4 controls. You can’t miss or mistake it, its obvious.

It is that easy to solve this mystery.

Cheers
 

OGBeno

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Look at the front of the tcase. H4 button operates vacuum tcase, it engages 4wd via vacuum switching valves. If you look at the tcase front out put there is a vacuum actuator which is what the H4 controls. You can’t miss or mistake it, its obvious.

It is that easy to solve this mystery.

Cheers

There are no 80 series trucks with vacuum cases. They are all mechanical.

The H4 button will only be applicable to trucks with an HF1A transfer case.
 

SNLC

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There are no 80 series trucks with vacuum cases. They are all mechanical.

The H4 button will only be applicable to trucks with an HF1A transfer case.

I figured with 8 different engine combos in 80-series around the world with a lot of models, some may have come with it. As you are well aware the vacuum actuated tcase was used on 70-series all through the 1990’s. That is also why I said looking at the tcase solves the mystery. Perhaps someone swapped in a 70-series powertrain? Or FJ62. 🤷🏼‍♂️

Cheers
 

OGBeno

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I figured with 8 different engine combos in 80-series around the world with a lot of models, some may have come with it. As you are well aware the vacuum actuated tcase was used on 70-series all through the 1990’s. That is also why I said looking at the tcase solves the mystery. Perhaps someone swapped in a 70-series powertrain? Or FJ62. 🤷🏼‍♂️

Cheers

Vacuum split cases are still being used currently.
 

OGBeno

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Are you sure? I don't think I've seen an HF1A with any electronic actuators fitted, I thought it was lever shift only.

They won’t have actuators but they will have position switches. Button on the dash doesn’t necessarily means it activates a actuator. A switch on the dash can activate a position switch as well.

In this case, activates H4.
 
Joined
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Beats me man. Look at the tcase, no vac actuator then it is obviously used for something else. Maybe they like to wire up their Hella H4’s to the H4 switch? Shouldn’t take but a few minutes looking at the truck to figure it out.

Cheers
It’s gotta be original. All three of the trucks I’ve seen here have had the exact same switch in the exact same position.
 
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Ok, so here's the deal. Those rigs have a HF1A part-time transfer case. Most of those are manual lever shift, but apparently there's an option for a "motor shift type" which uses the H4 switch and a motor actuator, as opposed to the "direct shift type" which uses the lever. This is described in RM184E, looking at page TF-49. What does the transfer shift knob look like on these rigs?
 

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