Centre Diff Lock switch

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Hi Julian,
I'm new to the list having only just joined but think that it/you may
have already answered a question that I was going to ask.
I've got an auto 80 series and I read in one of your posts that it is
possible to put in a centre diff lock switch. Like most users with an
auto, having the centre diff lock operate only when in Low range is a
bit limiting. There are times when it would be useful to lock the diff
whilst in High, and similarly times when I want to use Low without the
diff locked.
From your post it looks like I will need to buy the switch and connect
up the loom behind the dash, but what changes are needed to the
ECU/Transfer box wiring? I have pored over an electrical wiring book for
the 80 series, and it doesn't look too easy. However, the book was for
an earlier diesel model, not the later petrol one I have now.
On a similar vein, I want to replace the indicator bulbs with the newer
generation of LED bulbs. These will last longer (virtually never have to
replace them again, use far less power and consequently run cooler), but
the Toyota has a bulb failure device. If I replace all the 21w units the
unit goes into flasher overdrive thinking I haven't got any bulbs
working. The obvious answer is to wire two extra bulbs on each left and
right circuit under the bonnet but this does rather seem to defeat the
object of changing them in the first place!! Do you know if its possible
to wire out the bulb failure unit? The only downside to this is that I
would have to regularly check that all the bulbs are working (not so bad
a chore if you use the hazard switch).
----
Best Regards
David Roulson
 
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David
I've done the "centre diff-lock switch" mod (10 minutes to fit as the
wiring is all there inside the dash), but as I've got a manual gearbox I
then simply unplugged & sealed the switch on the transfer case.
With your auto box you may choose to get involved in the notorious "pin
7 mod" to keep the ECU happy, and I'll leave it to those with unmuscular
left legs to explain that!
I've replaced one tail light bulb after 4 years / 50k miles, and the
indicator bulbs are untouched. So I don't think indicator bulb blowing
is a problem on these vehicles, however ...
The wiring diagram says there is a "flasher" unit which controls the
flash rate, and goes on to say that it should operate between 60 & 120
flashes/minute with 2x 21w bulbs, rising to >140 / minute if a front or
rear bulb fails.
The flasher unit is "relay G in relay block 1", which I guess is the one
by your right knee.
You will have to replace this with an electronic one that is not
load-sensitive if you want to use leds, or alternatively wire a resistor
across the leds to simulate the load. These people
http://www.superbrightleds.com/1157.htm claim to have both flasher units
& resistors.
The real electrical gripes people have with these vehicles are (1) lousy
headlights, especially low beam; and (2) slow power windows in cold
weather.
The best solution to (1) seems to be a relief wiring harness +
over-wattage bulbs (and I think I've found a source of 130/100w ones in
Germany).
Opinions differ about (2), ranging from "dismantle totally, scrub out
liners & use silicone spray" to "I don't use the windows much in
winter".
Good luck, and nice to have you on the list.
Christopher Bell
Devon, UK
1996 1HD-FT
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Gareth Jones wrote:
Thanks Gareth, I've had a look at the site and seems like it might not
be too difficult. I'll try and figure out which plug to remove on the
transfer box (assuming there's more than one!)
David
 
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Christopher Bell wrote:
Hi Christopher,
I've never removed the dashboard with the radio in but I'm assuming
there'll be a couple of screws somewhere so hopefully it should be a
fairly quick mod. Gareth mentioned the site www.sleeoffroad.com and
they say that you can fit the switch to get the diff locked in High and
that removing the Transfer box plug will also enable Low switching.
That's what I'm after - High sometimes needs the diff locked and there
have been times coming down steep tarmaced mountain roads when I need
Low but without the diff locked.
With the manual gearbox and the switch fitted, are you able to switch in
the axle diff-locks after selecting the centre one or is that still only
available in Low range?
Now that sounds interesting and intriguing. Is this to do with the
centre lock or something else?
<Snip>
Thanks, I'll go off to their site for a look. I did think about putting
a resistor in but it'll need to sink about 3.5 amps which will mean it's
fairly large. The other reason for going to LED lights is one that
you've touched on below, the wiring. Having the LED's will mean the
wiring will be overrated rather than "just enough".
130/100w are quite large and I think you're right that you'll need the
better harness/relay combination, 10 amps down the size of wire that
Toyota fit will warm the engine bay nicely. I've got 100/80w fitted and
the standard loom seems to cope just about, the only problem I find is
that when the inner pair of lights are on and the outer pair are on main
beam, switching back when somebody approaches makes you feel like you've
just gone into a cellar!!
There is a fair range of bulbs available on ebay, of which quite a
number of the larger wattage ones seem to come from Japan. There's also
a number of 60/55w bulbs that give an effective 120/100w light, would
this be better?
I do get the same problem but I tend to take the second option and try
not to use them until the car's warmed up in the winter. Helps with a
Kenlowe heater fitted though as it's nice and warm when I go out to it
in the morning.
Thanks Christopher, it's quite re-assuring to have one question answered
after only subscribing to the list for one day!
 
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Hi David,
Welcome to the list.
The standard operation for the 80 series diff locks is that the centre diff
locks automatically when you engange low range and then once engaged you
can then activate the rear or the front and rear diff locks as well.
The front and rear diff locks can only be engaged once the centre diff has
locked.
You can overide this behaviour by fitting the centre diff lock switch
(standard item on some models). The CDL enables you to engage the Centre
diff lock in high range and thus also the front and rear diff locks.
To tweak things further you can also either do the Pin 7 mod (see link
below) or remove a plug from the transfer case to give you manual control
over the CDL in Low Range.
One thing some people find is changing points for the gears in Low Range
are too far apart requiring a lot of revving - if you do the Pin 7 mod this
gearing is maintained, whereas if you remove the plug from the tranfer case
you will get the same changing points as you do in High range, but with the
advantage of being in low.
You can find info on the Pin 7 mod at: http://tinyurl.com/72ev7
The tranfer case instructions are at: http://tinyurl.com/9v9a2
I hope that helps.
--
Regards,
Julian Voelcker
Mobile: 07971 540362
Cirencester, United Kingdom
1994 HDJ80, 2.5" OME Lift
 
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| Hi Christopher,
|
| I've never removed the dashboard with the radio in but I'm
| assuming there'll be a couple of screws somewhere so
| hopefully it should be a fairly quick mod. Gareth mentioned
| the site www.sleeoffroad.com and they say that you can fit
| the switch to get the diff locked in High and that removing
| the Transfer box plug will also enable Low switching.
| That's what I'm after - High sometimes needs the diff locked
| and there have been times coming down steep tarmaced mountain
| roads when I need Low but without the diff locked.
|
You pull out the ashtray, undo a couple of Phillips head screws either
side in there and, as I recall, gently prise off the a/c and radio
facia. I don't remember exactly, and it might have been necessary to
undo some screws in the radio enclosure too, but certainly it was easy.
The blank switch position at the top right has a connector tucked away
behind it which, on mine, was wrapped in foam (what an eye for detail:
it's easy to see why Toyota make money!) with a blanking connector in
it. You just plug it into the switch & that's that.
On the manual you can do what you like: once you've installed the switch
and disconnected the one on the transmission control of the centre
diff-lock is entirely carbon-life form-based (ie you!), and you can
(dis-)engage it in hi or lo range at will. I think the engine
management stuff on the auto makes life a bit more complex, but I don't
have any first-hand experience of that.
| With the manual gearbox and the switch fitted, are you able
| to switch in the axle diff-locks after selecting the centre
| one or is that still only available in Low range?
The interlock that stops the front and rear diff-locks engaging unless
the centre is engaged is still there, and also you still lose ABS when
the centre diff is locked. However since you can now lock the centre
diff in high range you can also do the axle ones in high too.
Personally I wouldn't since locking the axles means that you lose most
of the steering, which could be "interesting" at any sort of speed.
Both I and others have found that the axle locks won't engage at speeds
over about 5mph, but whether this is due to electronic interlocks or (my
opinion) good mechanical design I don't know. As far as I know once
engaged they stay engaged at all speeds, but I don't have a big enough
skating rink to put this to the test! The user manual says to come to a
halt and stop any wheelspin before engaging them, which feels like
sensible advice to me.
I don't find these limitations are an issue, but then I'm not a
hard-core off-roader as I just use my TLC for towing the children's
horses. So the most off-roady stuff it does is muddy fields (not trivial
with 2.5 tons on the towhook) and a bit of farming now and then.
For hill descent on tarmac with the trailer behind I've never had to
resort to low range, although there have been a few hills on Exmoor that
we've gone down in first. I've found that my standard brakes / wheels /
suspension setup is well able to handle an all up vehicle + trailer
combination of around 5.5 tons with no problems.
I have had to replace both front brake callipers though, as pistons were
starting to stick leading to pull to left or right on braking, but I
think this was due to old age not overheating. The autos seem to be much
heavier on their brake pads than the manuals.
Christopher Bell
Off road on steep mud I find 1st gear + low range + all feet off the
controls works like magic: you feel the occasional slither from random
wheels slipping, but it all seems to sort itself out
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Hi Julian
Just going over some e-mails and found yours on Diffs.
If As I do have the Diff switch on the dash along with the dial one just at
the steering wheel , does that mean I can engage it in high and not have to
bother with the low.
cheers
john C
92HDJ 80 1HDT Rep of Ireland
SNIP
 
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Thanks for the information Christopher. I ordered the switch from the
dealer today (hopefully arriving Saturday) and had the dashboard apart
putting in a phone car kit and spotted the connector. I should be
testing it by Saturday afternoon with a bit of luck.
I had used the top right blank for the LPG/Petrol changeover switch but
have now moved it to the lower bank where the rear heater control is to
make room for the new one. It deserves pride of place after learning of
the cost.
Like you, I don't think I'll be needing a cross-axle lock in high range
but I was curious to know if the facility was there. With regard to
steep descents, I have come down off some mountains on smallish single
width tarmaced roads and they can be fairly steep. I found that there
wasn't enough engine braking whilst selecting "L" on the auto box and I
was using quite a fair amount of foot braking. Not good when the bottom
of the valley is 2 miles down the road. I couldn't use low range as
there were too many hairpin corners.
Whilst I've always considered the LC to be the better vehicle than a L/R
Discovery or Range Rover (at least it's a proper 4-wheel drive vehicle
unlike the 2-wheel drive L/R's!), the one thing they had that was
missing was the ability to select whether you wanted the centre diff
lock in or out in either high or low range. Now I can do the same.
David Roulson
 
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Hi John,
Try and do the Pin 7 mod or remove the lead from the transfer case and then
you have full control.
--
Regards,
Julian Voelcker
Mobile: 07971 540362
Cirencester, United Kingdom
1994 HDJ80, 2.5" OME Lift
 
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I may be conservative but can't help thinking that Mr Toyota thought of all
this when he was designing the car in the first place, so he thought that
when in low, best put the centre diff lock on. My car has dash switch for
centre diff and separate switch for the front and rear and being a Japanese
import vehicle is unusual in that. So I can switch the centre lock on in
high when I want. But on the occasions in Morocco recently when I used low,
I was pleased that the centre lock went on automatically. One less thing to
trouble my brain when I was searching for the perfect tripod position for
the next photograph...
I remain unconvinced about the need for the 7 pin mod... But loads of TLC
owners down under have done it so maybe there is something in it...nah! How
silly of me, we won the Ashes...
Snow coming..
Jeremy
On 23/12/05 19:00, "Julian Voelcker" <[Email address removed]> wrote:
Jeremy Llewellyn-Jones
Mob: 07831 458 793
--
 
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Jeremy,
There certainly is a need for the pin Seven mod, depending on
your use of the vehicle. The same as there is a need for a long range
fuel tank, if you need it. Someone at Toyota deemed that the diff
would be locked automatically in low and so it is. Toyota however have
to try to be all things to all men, this is not easy and usually
results in a compromise. If ever you have tried to reverse something
very slowly, and you put the vehicle in low box to do this , then the
lock becomes a pain that you are better off without. By doing the mod
you are not taking away the facility, just allowing yourself to
control it.
Regards, Clive.
On 12/23/05, Jeremy Llewellyn-Jones <[Email address removed]> wrote:
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Hi all you there...
I have seen only 2 LC HDJ 80. Mine and the one who is most successful
car seller of TLC in Norway.
Now his LC was 94-mod and it has a dash switch for senter diff,
though mine doesn't -mine is 96-mod 24-valves.
Maybe 'mr.Toyota' really had found out we don't need that dash
switch......to make our life easier for those of us
who can't do anything themselves and doesn't care anyway. If you
going to seat fast in the mud maybe the tractor is
the best solution :-(
Lubo
On Dec 24, 2005, at 11:40 AM, Clive Marks wrote:
 
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