4H & 4L Icons

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Real_Mcoy23
Posts: 33
Joined: Sat Apr 29, 2023 4:02 am

4H & 4L Icons

Post by Real_Mcoy23 »

So yesterday was the first time using 4L on my d-max, I don't really get much opportunity to use it but yesterday was one.
I would say it worked ok, I'm new to using 4x4 so any advice is appreciated, but what I really wanted to ask, when you enable 4H and 4L doesn't an icon light up on the cluster stating that it's enabled?
When I enabled it I just waited to feel and hear it engage, but didn't see any icons
Mike C
Posts: 146
Joined: Fri Dec 10, 2021 7:13 am

Re: 4H & 4L Icons

Post by Mike C »

Mine has the 4H and 4L lights come on after they engage. I have to stop it to engage 4L from 2L - it engages after a bit of a thunk-then the 4L light comes on.
mydmax
Posts: 2103
Joined: Sat Oct 12, 2013 8:36 pm

Re: 4H & 4L Icons

Post by mydmax »

Mine is a 2011 Dmax, when H4 is selected the system flashes the light on the dash until it actually completes selection, which is, First joining the front axles together By the SOTF unit, and only then does the Transfer case select H4. While doing that the lights H4 light flashes. and remains ON if in H4 and shows H4. Then If L4 is required the transfer case only has to change the transfercase ratio to LOW. If the L4 button or rotary selector in later models is selected, the L4 will flash until it completes the process. When in L4 it should show constant L4 on dash.
If the vehicle is totally stopped and no slight movement of wheels, if the front SOTF spline is not aligned or the DOG Clutches in the transfer case are not in aligned position, the change controller will "time out" it's trying and NO lights will show and nothing is engaged.
Slight movement of the vehicle while selecting will help all the bits inside line up so it can change. Selecting H4 you might hear a small clunk but selecting L4 usually causes a louder CLUNK as the large heavy DOG CLUTCH in the transfer case is engaged. All these changes/changers are driven by servo motors on either the front axle and also on the rear of transfer case. Changing to L4 from H4 must be done STOPPED or Slightly rolling/moving, ie 50mm travel.
L4 selection or deselection while moving with any force or speed will cause transfercase damage. so slight movement with no torque applied. If you do it on a slight slope, releasing the brake momentarily will allow that slight aligning movement.
garrytre
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Location: adelaide hills

Re: 4H & 4L Icons

Post by garrytre »

When you first turn on the ignition, and every dashboard light tests itself, don't you see a little set of 4 wheels, the front ones turned a bit? And a '4L' icon beside it?

2H, 4H and 4L can be confusing at first. They are 3 separate things, so asking 'when you enable 4H and 4L' is not meaningful.

Think of 2H -> 4H -> 2H as your gearbox driving the back wheels while the front wheels are doing the same speed, so (purists will hate this description) another gearbox (the transfer case) can engage the front wheels without using a clutch. That's the idea, doesn't always work.

Now think of 4H -> 4L -> 4H as yet another gearbox, this time with different ratios, so internal parts wanting to do different speeds. Like changing a manual from 3rd gear to 1st gear without a clutch, something will break. So you gotta stop the vehicle to change ratios.

In practice, 2H -> 4H -> 2H sometimes won't engage, so the icon flashes for a while until the beeping starts. Turn our knob back to 2H, drive around a bit and try again.

Having different sized tyres, eg some new and a worn spare can stop it, and being on sand (I presume wheels turning at different speeds) can stop 2H -> 4H working properly.

The manual says you can change from 2H to 4H up to 100km/hr, the dealer mechanic that I complained to says you have to stop, and sometimes you do have to stop.

One thing is, don't get to a dune, or a creek, and assume that putting it in 2H -> 4H will work when you want. If you have your rear wheels spinning when the front ones finally engage, ie front & rear doing different speeds, there'll be a godalmighty thump and something might break. So again, change 2H -> 4H befoer the last minute and check that it has worked.


That's the vagiaries of electronic 2 -> 4 and H -> L on lots of cars, not just D-Max. We'd all bitched about the good ole days when a metal stick pushed things into place and you knew it, but those days are gone.

There's a whole nother aspect to 4WD. Several people have asked me to teach them how to 4WD, and 2 things are apparent. First, they can't drive in the first place. Second, they think it's kinda something to do with the car, and I have a bugger of a time convincing them that it's all about the interaction between the car and the ground. They think rocks, and slopes, and mud and sand will all magically disappear once they've put it in 4WD and I have to make explicit that they've learned to drive on flat bitumen roads that have good grip, and that this place is different. Basically we get out and walk for a while, looking at the ground, then we get into the car and learn to drive in 2WD, and once they can do that, they usually don't need 4WD. And I despair when I see people in $100k of new gear stop and use 4L on dirt roads where I would never bother, usually commentating some crap they saw on youtube to their mates on our UHF repeater. sigh
If it ain't broke, fix it til it is.
mydmax
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Re: 4H & 4L Icons

Post by mydmax »

Garrytre. A good description and explanation there, nice job!
I might add for the OP, that when changing from 2H to 4 H which must happen anyway. Unless the SOTF unit has engaged AND the two front axles are now going at the same speed, ie, can be stopped or while moving, the SOTF unit feed back switch loop, a 3 wire system for detection of engagement, has CLOSED. Only then does the controller KNOW the drive shaft to front diff is going at the same rotational speed or very close to it as the rear tailshaft. If all is both are going the same speed, the controller will then allow and cause the 4H to happen withing the transfer case. All the parts involved at that time, are at or near to, the same speed condition and the 4H dog clutch can simply drop in seamlessly, a bit like a motorcycle gearbox internal action.
I changed from 2H to 4H to 2H to 4h, many times on the Oodnadatta track when very muddy and towing a Tvan. Usually around 40to 5kmh. Unless he SOTF spline to lock front axles together are inline then is will not change.

The 4H to 4L is a whole different operation where the now front and rear drive shafts are running at same speed, 'cos they are locked together now. BUT when going to LOW ratio will not incorporate a an Epicyclic gear train which HAS to have different, large heavy components changed for a Higher speed to a Lower speed. That means it must be stopped or just slightly moving so it can perform the change without a BANG and damage to dog clutch or operating forks. If not aligned, the servo motor action will "time out" and unless the parts are rotated slightly it won't EVER change to L4.

Seeing it is an open diff vehicle, when you think it is in 4 something, jack up 1 front wheel and try and turn it. If you can rotate it more than 1/16th of a turn, then 4WD is not engaged, no matter what the lights do or don't tell you. Because the system uses feedback to determine changed parts positions, the lights are simply to show the status. If it is all OFF then only 2WD HI suspect.

There is more jacking of wheels and relative speeds of wheels while manually turning to be done for further diagnosis, but the explanation is more involved.
garrytre
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Location: adelaide hills

Re: 4H & 4L Icons

Post by garrytre »

mydmax wrote: Sun May 28, 2023 2:41 pm Garrytre. A good description and explanation there, nice job!
thank you
If it ain't broke, fix it til it is.
garrytre
Posts: 708
Joined: Wed Feb 05, 2014 4:22 am
Location: adelaide hills

Re: 4H & 4L Icons

Post by garrytre »

did this guy ever write back and say thanks?
I wonder how many of these are robots or scammers.
If it ain't broke, fix it til it is.
mydmax
Posts: 2103
Joined: Sat Oct 12, 2013 8:36 pm

Re: 4H & 4L Icons

Post by mydmax »

G'day Garry
I don't think these people ever return or reply. Some may be bots but many humans don't seem to appreciate any suggestions they can act on. Once their problem is solved it is mind over matter, They don't mind and you don't matter. It is a take take world now. Then there are the ones who do appreciate possible solutions and reply in a positive manner.
Real_Mcoy23
Posts: 33
Joined: Sat Apr 29, 2023 4:02 am

Re: 4H & 4L Icons

Post by Real_Mcoy23 »

Haven't been here for a while things got busy with me
You guys know your stuff when it comes to 4x4 much thanks for the info I read ps I'm human
When I put the ignition on usually all the lights on the dash should illuminate I don't think I see any icons pertaining to 4h or 4l
Maybe you guys can share sum pictures of your cluster
I'll share mines too
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