Operating 4WD in a Toyota HiAce LH100
Toyota HiAces of this era came with three types of drivetrain. Two Wheel Drive (2WD or RWD), All Wheel Drive (AWD) and Four Wheel Drive (4WD). This post discusses the 4WD system fitted to the LH100 models. AWD is not the same thing as 4WD and is an automatic system and not discussed in this post.
HiAces were fitted with Automatic (Auto) and Manual transmissions. Note that L on the Auto selector is not Low Range (L4) as discussed in this post, it merely locks the transmission into First Gear. Where I mention Park or Neutral, I am assuming that Neutral is sufficient on a manual.
Identifying your model
The 4WD model came as standard with 15″ rims and six wheel studs.
There is a 4wd button on the dashboard and a High/Low lever on the floor (just in front of the gear change lever).
The front hubs are free wheeling hubs (standard are Aisin hubs with a red centre).
Under the van you can see the transfer case behind the gearbox, with prop shafts running to both the front and rear differentials. You’ll see drive shafts running to the front wheels.
4WD
In normal running, the 4WD system is not engaged and the van is running in 2WD, with power to the rear wheels (RWD). The front hubs are not connected to the front drive shafts, so they spin freely, as with a 2WD van. The front differential is not connected to the gearbox, so the front prop shaft will not be turning.
With 4WD is engaged the front wheels are connected to the front drive shafts and the front differential is connected to to the gearbox via the transfer box. The transfer box locks the front and rear together, so that 50% of the power is sent to the rear and 50% to the front.
In this way, you need to loose 100% of traction to one front and one rear tyre before you lose the ability to move.
Engaging 4WD
Bring the vehicle to a halt. Put the vehicle in Park or Neutral. Apply handbrake if required.
This handy sticker on the dashboard tells us what to do next. If you don’t read Japanese, I’ve translated it to English for you 🙂
Turn the red centre of the front hubs clockwise, from Free to Locked position.
You will need to do this on both front wheels.
This action locks the hubs to the driveshafts.
Push the 4WD button on the dash. You may hear a click and you should get a green indicator light in the instrument cluster, but don’t panic if it does not come on immediately.
This action causes the transfer box to send power to the front axle.
Put the vehicle into gear (release handbrake if applied) and drive.
If the indicator light has not yet come on, it may take a few metres of driving to get the system to engage and then the indicator light will illuminate.
Mud will no longer be our mortal enemy.
Edit [January 2024]: I’ve been told it’s possible to engage/disengage 4wd while moving (obviously you will have previously needed to have locked the hubs), rather than coming to a halt first. I have never tried this, so cannot confirm this.
Edit [April 2024]: I’ve now had the opportunity to test this and have engaged and disengaged 4wd while moving at slow speeds.
Low Range Gearing
In normal operating conditions, you will be in High Range (H) irrespective of whether 4WD is engaged. You may want to have more control by moving more slowly for a given engine speed. By engaging Low Range (L4) the wheels will turn 2.5 times slower. This can also reduce the risk of wheel spin and I will often use Low Range on the campervanner’s worst nightmare – wet grass.
Engage 4WD. Ensure the 4WD indicator light is on. The low range lever will not move unless 4WD is engaged.
Put the vehicle into Neutral (The Auto will not allow the lever to move in Park). Apply handbrake if required.
Move the lever into the desired position. Forwards for High (H), Backwards for Low 4 (L4). Note that High is the normal position and is used with both 2WD and 4WD. Low 4 can only be used in 4WD.
Put the vehicle into gear (release handbrake if applied) and drive.
Disengaging 4WD
The process of disengaging 4WD is the almost the exact opposite of engaging 4WD:
Bring the vehicle to a halt. Put the vehicle in Park or Neutral. Apply handbrake if required. Ensure Transfer Box is in High (H).
Push the 4WD button on the dash. The light should go out, but may not go out immediately.
Turn the centre of the front hubs anti-clockwise from Locked to Free position.
Put the vehicle into gear (release handbrake if applied) and drive. If the light has not already gone out it may take a few metres of movement for the system to disengage, but it should after a couple of seconds of moving.
Differentials
As standard, the HiAce has open differentials (7.5″ front, 8″ rear).
Some 4WD HiAces were fitted with a Limited Slip Differential (LSD) in the rear, so even if one rear wheel is spinning, power will still be delivered to the other rear wheel, so you need to loose 100% traction on both rear wheels and one front wheel before you lose the ability to move. You can check if you have an LSD by looking at the silver builders plate under the engine cover. It will show an axle code Gxxy. If y is 3 or 5 then an LSD was fitted at the factory.
If you do have an LSD you need to use LSD specific differential oil. An LSD is an automatic system and does not require the driver to do anything to operate it. Beware, the LSD may no longer functioning correctly if the incorrect oil has been used and may behave like an open differential.
When To Use 4WD
Use 4WD on loose or low traction surfaces where there is a risk of losing traction between tyre and ground. Mud, gravel, sand, wet grass, for example. 4WD alone may not be enough to provide traction, and other off road tricks such as lowering tyre pressures may be required. There are no speed restrictions to using 4WD.
NEVER engage 4WD on a grippy surface, such as dry tarmac. The system needs the wheels to be able to slip to reduce loads building up in a single part of the system. If wheels cannot slip slightly, the system starts to bind up and there will be increased wear on the drivetrain, or even a failure of a component.
You can drive safely with the hubs locked, but without 4WD engaged. You may want to do this if you are frequently needing to engage 4WD, or to keep all the components moving and lubricated. I do this every now and then.
You can also drive safely with 4WD enabled, but the hubs unlocked. You may want to do this to keep the components moving and lubricated. I do this from time to time. It may also be useful if you need to put the vehicle into low range on a grippy surface, such as a very steep hill. This can help get closer to max torque and also keep the water pump and cooling fan running faster to cool the engine as the engine will be at a higher RPM relative to the speed of movement than in High Range.
Problem Solving
4WD will not engage (no light on dashboard)
Possible issues are:
- Vehicle needs to be driven further to engage. It should not need more than a few metres though.
- Dashboard light not working – bulb or other electrical gremlin. There is a sender on the transfer box.
- Vacuum system issue. The transfer box is vacuum actuated. Ensure all vacuum pipes are connected to the transfer box. You can test if the vacuum system is working by removing one of the pipes and checking for vacuum when the switch is engaged. It should be possible to hear the actuator ‘click’ when 4WD is engaged.
Free wheeling hubs do not turn or are very stiff to turn
It should be easy to rotate the free wheeling hubs from Free to Lock by hand. If not, it is likely that the hubs need servicing. It’s easy enough to do – there are plenty of YouTube tutorials and only basic tools are required. Alternatively, find a 4×4 specialist, these types of hubs are common on 4WDs, especially Toyota and Nissan models.
4WD will not disengage (light will not go out on dashboard)
Possible issues are:
- Vehicle needs to be driven further to disengage. It should not need more than a few metres though.
- Drivetrain has bound up. Drive onto a low traction surface that will allow wheels to spin.
- Unlock freewheeling hubs
Vehicle has no drive
Ensure High/Low 4 lever is properly engaged. You should feel it ‘notch’ into position. It doesn’t require a lot of force, just a gentle push. Unless it does, the transfer box will not be connected to any of the prop shafts.
Cannot move the High/Low 4 lever
- Ensure you are in Neutral (N). It will not move in Drive (D). It requires a gentle push to engage, but do not use excessive force.
- Cable or linkages seized. Replace cable, free and grease linkages.
I’m still stuck
4WD is not a magic button. You can get a 4WD stuck, just usually further from help. Top tip, drive in using 2WD, use 4WD to get you out…
Even with 4WD, road tyres will easily lose traction on loose surfaces. All terrain (AT) tyres will give better grip in low traction surfaces. Mud terrain (MT) are a bit overkill on a HiAce, but I have seen them fitted. The cost of this change is increased fuel usage, increased tyre noise, reduced water shedding on wet roads and reduced tyre life compared to road tyres. Lowering tyre pressure can help on some surfaces, such as sand and mud. For use in snow and icy conditions, look for winter rated tyres.
Applying some handbrake can help get the stationary rear wheel turning by simulating some traction on the freely spinning side. You can also try wedging things under the spinning wheels to get traction. Beware of loose items being fired out by the tyres.
HiAces have terrible ground clearance and the underbody has little to no protection. The Auto transmission sump is particularly vulnerable. It may be that part of the chassis or other component is digging in. A 50mm lift (rear suspension shackles from Blood Red Offroad, wind up the front torsion bars to match) is probably about as high as you want to go without stressing the CV joints if this is a regular problem for you. I got another 25mm of clearance using 16″ rims and 215/70R16 AT tyres. Beware, altering the ride height of the vehicle will change the handling characteristics and will require wheel well alterations (with a hammer!) to fit larger tyres.
It is possible to fit an aftermarket LSD, auto locking and manually locking differentials to the HiAce, they are common Toyota sizes and are shared with 4Runner (HiLux Surf) and some HiLux models of the same era. You will need to be aware of the diff ratio, which you can find from the builders plate as pictured in the Differentials section. In this case the xx value from the axle code of 14 indicates a ratio of 4.875. So G142 is a 2 pinion open centre diff with a ratio of 4.875.
Enjoy!
The HiAce is not an Off Road vehicle. It lacks clearance, underbody protection, suspension flexibility and as most are converted to campers, they are both generally heavy and top heavy. However, they are still surprisingly capable and the 4WD system combined with suitable tyres will keep the vehicle moving on soft and low grip surfaces.
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Hi!
A few questions about your tires!
You mention needing some wheel well alteration to fit the larger tire, so 215/75R16 doesn’t fit only with the 50mm lift?
Also, which AT tire in 215/75R16 did you find? I only find van tires in this size.
And lastly, what do you use to put the tire in the back? (Is-it supported by the hatch?)
Thanks!
I subscribed on Facebook to follow the adventure !
Hi Felix, thanks for the follow 🙂
The back of the front wheel wells need slight reshaping with a hammer to avoid tyre scrub. I still get a small amount of scrub on maximum compression while turning (on the mudflap, I think), but that is a rare occurrence. Note I have used ET08 rims, so have a slightly wider tyre track, I can’t comment on whether it would be an issue with other offsets (standard is around ET38 I think)
I use General Grabber AT3 tyres. They’re not van tyres, but the load rating is sufficient. I have been very happy with them, we’ve been off the beaten track a lot through Greece and Türkiye and so far not got stuck or damaged the tyres! Tyre wear seems good and they are winter rated as well.
The spare tyre is mounted on the tow bar using a bak-rak fold down bracket (https://bak-rak.com/product/wheelrak/). It is not mounted by the hatch. It works, although there is some play. It’s a pain if you are using the hatch a lot as it is in the way when folded down.
Thanks again for the follow, I am hoping to catch up with blog posts soon.
Thanks for the detailed answer!
Yes the Grabber AT3 is on my list of tires I’m interestingly looking at currently! But as far as I know it is not available in 215/75R16. Maybe you are on 225/75R16? Load Index is high on this size so it would match the Hiace need (104 on mine).
I plan to keep the stock euro-market wheels which are 16×6 ET30. I’m looking at 205R16 tires which are very slightly smaller than 225/75R16 and narrower. But I’m still not sure they 100% fit x)
Also looking at the exotic 195R16, from time to time there is a batch of Yokohama G016 and G003 in this size, but otherwise it’s a non existing size. It has the big advantage to be a legal upgrade in France.
Always interesting to see other 4wd Hiaces traveling 🙂
I must have made a typo somewhere, we’re running 215/70/R16. Load rating on them is 100 (800kg). 195R15s were fitted to the van when we bought it, but they delaminated on our first trip! Probably the van had been stored for a long time.
Interesting that the Euro Aces have larger wheels than the JDM models, which are all R15. If you are going bigger, I’d recommend getting an engine (and if auto, transmission) temperature gauge. You’re putting more load on the engine and slowing the fan speed. I see my cylinder head and transmission temps raising (CHT often goes from 84c to 100c) on long climbs but never see the stock temperature gauge move! It gives you advance warning to take some action, like running the heater which can bring temperatures down by about 10c.
There’s a few HiAces out travelling, Mad Nomad is in South America, as were Fearless on Four Wheels, although I think they have finished their trip now. There was a Dutch family who drove theirs to Japan a few years ago. Sadly HiAce Hobo took all of his content offline, he had some good info 🙁 If you’re looking for more info on HiAces, you can join “The Toyota HiAce Camper Group” on FB. A few knowledgeable people on there. There’s other HiAce groups, but this one seems best. You just have to get past the interview with the Admin first 😀
I found the mistake and have updated it to 215/70/R16.