Centre Diff Lock Dash Light

[LenGXV6 Member Find all posts View Profile Close LenGXV6]

Re: Centre Diff Lock Dash Light

Finally got under the back, and what toyota told us was wrong......after clearing away the dirt I found the LSD oil only sticker, so I posted wrong and yes the early model GX does come with LSD.

This is the sensor I found with the broken case


and then further back on the transfer case I found this one


I am going with sensor 1 as being at fault, would love to know what the other one does though. Both are on the drivers side.

[Whitey Shockie Maker of the Month Award Find all posts View Profile Close Whitey]

Re: Centre Diff Lock Dash Light

G'day everyone,

I'm new to the forum, just got myself an 05 GXL Prado, 4lt auto, after having been driving an old 60 series around for a while. Am lovin every minute in the Prado, such a fantastic car to drive ! I feel like I'm driving around my old WB V8 ute ! Haven't had it off road yet, but am looking longingly in the direction of Fraser !

I have one small problem, my diff lock light doesn't work, and after reading all of the available threads, I have been underneath, and pulled apart the 2 blue and 1 grey connectors on the transfer case, all of which were in very clean condition (the car has never been off road). I light tested all connecters from the battery while they were pulled apart, and couldn't see power on any of them (earthed the light tester to the chassis, with accessories on, and tested in high and low range). I sprayed them with WD40 anyway, but still no light !

I have checked the 20 Amp diff lock fuse inside the cabin, and it is also fine.

Also, the diff is clearly locking, as I've been up and down the hill outside my place and around a few corners (in both high and low), and I can hear the tyres complaining loudly !

As such, I have a few questions which I hope the forum experts might be able to help me out with....

a) why can't I see power on any of the blue and grey connectors with my light tester ? This makes me think that there is a problem between the cabin fuse box and the battery ???

b) are there any other fuses besides the 20 Amp cabin fuse which are in series for the diff lock light ? Any other places I should check ?

c) I started to pull apart the trim in front of the instrument cluster, as I wanted to double check it wasn't simply a blown bulb, but I rapidly got stuck, I found two plastic screws in the top part of the front trim, but then the bottom part of the trim wouldn't come out, it's clearly stuck behind the bottom dash trim below the steering wheel. I have a Max Ellery manual, but it only covers details about pulling apart a 90 series dash. Does anyone have a procedure with pictures and screw locations so I can pull everything apart and finally get to the instrument cluster panel ???

I did a lot of electrical work on my 60 series, but all these computer chips in the Prado means a lot more trouble shooting, so I'd really appreciate any help I can get with this very naughty diff lock light !

Thanks everyone !

[Matt Senior Member Find all posts View Profile Close Matt]

Re: Centre Diff Lock Dash Light

Ill get under mine on the weekend.. and have a quick look at it...

anyone else help this guy out.. he is my cousin.. and i think he is about to take half the car apart to track this down.. the man is loosing sleep, and will drink up all the bundy supplies if someone doesnt help him :P :lol:

[MickL Addicted PP Member Find all posts View Profile Close MickL]

Re: Centre Diff Lock Dash Light

Did you test the switches while you where under there? They are going to be either normally open or normally closed contacts (Check between pins and also each pin to earth). Test them with a multimeter and see if there state changes when you shift betwen lock/unlock.

You will also need to check connector voltages with the multi meter not a test light. The light runs through the ECU and the voltages are more likely to be 5 volt not 12.

Also I've been led to believe the light in the dash is a LED, not a glode.So it's very unlikely to be blown as they have a long service life.


Mick

[Whitey Shockie Maker of the Month Award Find all posts View Profile Close Whitey]

Re: Centre Diff Lock Dash Light

G'day Mick,

Thanks for your reply.

Just got the car up on ramps again and checked all the connectors with a multimeter.

With the car parked in low range on top of the ramps, and no power:

Blue connector (pass side) 0.22 V
Blue connector (driv side) 0.00 V
Grey connector (driv side) 0.00 V

With the key at ON position, low range, diff locked:

Blue connector (pass side) 11.74 V
Blue connector (driv side) 11.75 V
Grey connector (driv side) 11.76 V

With the key at ON position, high range, diff locked:

Blue connector (pass side) 11.76 V
Blue connector (driv side) 11.77 V
Grey connector (driv side) 11.76 V

So all the connections are getting 12 volts, which is strange if they are NO or NC contacts.

I tried my light tester again on every single pin, and earthed off the chassis, the body and the transfer case, and couldn't see current flow at any stage of my test.

I also tried to measure the resistance of the sender unit, which was pretty hard to do, as the connector is mounted on the side of the transfer case, and you can't position the multimeter probes very easily, but my wife said she saw between 3 and 9 ohms flashing up when I managed to finally hold them still against the pins.

Considering that I do see a finite resistance on the sender unit, my guess then is that the dash light must be dead, as the 20 A cabin fuse is fine.

If it really is an LED, I agree with you it should have a long lifetime, however, I have read in the threads here that some folks have never had the diff lock light work right from purchase of new vehicles, and I've had my fair share of diodes die on me, mostly cheapies from SuperCheap though !

If this diff lock light problem is really not a broken LED, and the sender unit seems fine (finite resistance), and we get 12 V everywhere, is it possible then there is a general fault in the ECU chip ???

I'd still like to pull the dash apart, and pull out the LED (or bulb or whatever it is), and just test it across the battery.

Any help on pulling the dash apart would be greatly appreciated !

Any ideas on where to go from here ???

Thanks again !

[MickL Addicted PP Member Find all posts View Profile Close MickL]

Re: Centre Diff Lock Dash Light

The "sender unit" is a simple switch, it's the part that has the N/O or N/C contacts either between the pins or to earth... I'd confirm it's operation before you start pulling the dash apart.

You can also bridge the loom connector pins to isolate the switch out of the circuit and prove if it's working or not.

Sorry I'm at work and don't have my wiring diagrams here to follow the circuit through.

Mick

[Whitey Shockie Maker of the Month Award Find all posts View Profile Close Whitey]

Re: Centre Diff Lock Dash Light

Thanks Mick,

Good advice, I bridged the loom connector on the driver side, and the diff lock light came on - is it meant to be orange ?

I also bridged the blue connector on the passenger side, but nothing happened, so I'm guessing the blue and grey connectors on the passenger side go to switches for something other than the diff lock ??

So either the switch itself, or the connector is dodgy.

Any advice on testing the switch ?

Thanks again !

[MickL Addicted PP Member Find all posts View Profile Close MickL]

Re: Centre Diff Lock Dash Light

Good work,

Yes the light is orange (On my 05 GXL as well)

You can remove the switch and bench test it. (It screws into the box) Give it a good clean with some contact cleaner/light electrical lube and see if it comes good. Other than that you may need to replace it.

BTW: It's above the level of the oil so you won't have to drain the box :wink:

Mick

[Whitey Shockie Maker of the Month Award Find all posts View Profile Close Whitey]

Re: Centre Diff Lock Dash Light

G'day again Mick,

I'll pull out the switch and give it a clean up, hopefully this weekend !

Just wanted to double check that the blue and grey connectors on the passenger side are not part of the diff lock light circuit, just to make sure I don't need to pull out all three ??? If they aren't part of the circuit, do you know what they are for ? ...I gotta get myself a Prado electrical handbook !!

Thanks again mate !

[MickL Addicted PP Member Find all posts View Profile Close MickL]

Re: Centre Diff Lock Dash Light

Just wanted to double check that the blue and grey connectors on the passenger side are not part of the diff lock light circuit

As far as I know one is a signal to the Auto trans ecu and the othe the engine ecu.
The one you have tested is for the light on the dash only.

The center diff lock is purely a mechanical device (on gx/gxl without traction control) the switch is for the light only, it has no other electrical parts. to make it work.

When I have time I'll trace threw the diagrams an identify exactly what each of the other two switches do and which is which.

Mick

[MickL Addicted PP Member Find all posts View Profile Close MickL]

Re: Centre Diff Lock Dash Light

A bit of further reasearch:


Connector D1 (Blue Connector, white wire + white wire with black trace) Diff lock postion (for light on dash)

Connector D2 (Blue connector, green wire with white trace + white wire with black trace) Low/high range postion (for VSC/ABS/Traction control ECUs)

Connector D3 (Gray connector, green wire + white wire withblack trace) Transfer neutral position (for engine ECU and auto trans ECU)

Wiring diagram dated 8-2006. V6 petrol/auto trans so wire colors may change for other models....

And just to confirm.... lights in instrument cluster are LED's


Mick

[Whitey Shockie Maker of the Month Award Find all posts View Profile Close Whitey]

Re: Centre Diff Lock Dash Light

Awesome work Mick !

Was wondering where do you get hold of the wiring diagrams ??

I'm gonna rip out the switch this weekend, hopefully the contacts are just stuck, as the bloke I bought the truck off had never used it for 4wd'ing. Do you reckon the switch could just be covered in dried oil, or is the switch sealed inside the case ??

...also for anyone else interested, I discovered at the wreckers that the 90 series have the same blue and grey connectors, so I cut off a blue connector and shorted the wires to make myself a nice bridge. Maybe the 90's even have the same switch in the transfer case ??

Thanks again !

[MickL Addicted PP Member Find all posts View Profile Close MickL]

Re: Centre Diff Lock Dash Light

Your on your own from here... I've never had the switch out to see how it works.

The switch is a common part across various Toyota models with this model transfer case... Surf, Hilux, Prado 90 and 120 etc...

I got my wiring diagrams from my local Toyota dealership spares dept.


Mick

[LenGXV6 Member Find all posts View Profile Close LenGXV6]

Re: Centre Diff Lock Dash Light

I found a site some time ago about the American Lexus 470(I think - same model as our Prado), This guy had pulled apart one of the sensors and had some really neat diagrams on how they work. If I can find it again, I will post the link

EDIT: Maybe I should learn to look harder before posting, found it 30 seconds later..............

http://www.monkeeworks.com/articles/...itch/index.php

Hope this helps everyone. :lol:

[Whitey Shockie Maker of the Month Award Find all posts View Profile Close Whitey]

Re: Centre Diff Lock Dash Light

G'day Len,

Nice detailed link ! ...just a small note for everyone, I think the LX470 is the Lexus version of our 100 series landcruiser, and the GX470 is the Lexus model of our Prados (at least thats what google images are telling me !).

I had a look under my neighbours 100 series, and yep, the link picture looks exactly the same, with that grey molded switch on the back of the transfer case.

...but on our Prados, its a different setup, the diff lock switch housing is circular in shape, and is on our driver side, right at the top of the case, almost at the back. You can recognise it by the two wires which run further up to blue connectors, which are the connectors that are causing all the trouble.

Believe it or not, my switch started working, after I had scratched up the connectors with my multimeter pins, while I was trying to measure the resistance. ...after I just got myself a long ring spanner to pull the switch out !

I've since sandpapered the terminals and sprayed both connectors with contact cleaner, and my diff lock light is now workin !

Thanks again everyone for your helpful links and ideas !