Disconnecting the A.D.D on 2016 Hilux sr5

Disconnecting the A.D.D on 2016 Hilux sr5

Postby septhilux on Sun, 25 Feb 2018 10:41 +0000

Hey Guys,
Has anyone worked out how to disconnect the A.D.D so i can select 4wd Low without the front diff connecting, for up hill reversing of trailers etc.
I found the mod for the previous model, is it the same for the current model?
Thank you.
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby Pizza on Mon, 26 Feb 2018 4:12 +0000

I asked the same thing and was told to have look behind glove box meant to be the same?
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby Surfseeker on Sat, 28 Apr 2018 10:52 +0000

So, has anyone actually done this mod on a Gen 8 that can confirm it is the same and does work on the new model?
I pick up a new SR5 next week and despite my wife already being cross at me for buying lots of trick gear for a vehicle that I don't even have yet, I can honestly say that this will be one of the first things I do....If it works...
I did this mod on my last Hilux, as I'm sure many of us did, and for me, this, and the rear seat mod (For a total cost of about $20) were two of the most useful mods I did to it.
I'm sure somebody must have attempted it by now?

The rear seat mod seems to be a no go, so Ill have to find somewhere else to store the maxtracks and other recovery gear that I had stashed back there in my previous truck :(
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby adamkberger on Sun, 29 Apr 2018 3:57 +0000

Here's the electrical schematic for the ADD. You could easily interlock one of the cables going to the motor to stop it from engaging. The trick is fooling the 4wd ECU into thinking you're in 4wd. Without acknowledgment from the ADD that you're in 4wd, the 4wd ECU won't allow the transfer case to engage low range. Looking at the diagram, there seems to be two sets of contacts, both connected to ground. The ADD cable goes to the 4wd ECU (not pictured) and the brake controller (not pictured) and could be responsible for signalling the 4wd ECU that your'e in 4wd and changing or disabling the ABS. You could simply ground pin 3 and you're good to go. I can't work out what DL1 and DL2 are doing. I'm thinking that it could be signaling the 4wd ECU which position the sliding collar inside the diff is in. If i'm correct, one of these cables will need to be grounded otherwise the 4wd ECU might freak out.
Image
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby numberplate on Sun, 29 Apr 2018 4:40 +0000

only way to find out is to use a multimeter on pins 3 . 5 and 6 when in low range , see what the switch conditions are. then replicate these conditions with a relay.

i have a feeling that pins 5 and 6 are responsible for changing the dash lights to locked , unlocked etc
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby Surfseeker on Sun, 29 Apr 2018 6:58 +0000

Thanks guys.
Not sure if you are aware but there was a very simple way of doing this on the Gen 7.
See below:

1, Remove the glove box and locate the 4WD ECU, located on the LHS of the glovebox and mounted on the side of a supporting metal structure of RHD vehicles. It has a green plug going into it.
2, To test you have the correct ECU disconnect the plug and then engage 4WD, with the ignition on no 4WD light should be on.
3, On the green plug there are six (6) wires coming out of it. Locate the black wire, check my shed profile and have a look at the photo of the plug and the wire in question.
4, Cut the black wire, solder two lengths of wire (a few feet long, or long enough to reach your desired switch position), one to each cut end then connect the lengths of wire to a switch to complete the circuit.
5, Fit the switch in your desired position. Replace the glovebox.
6, Hey presto you now have a manually disconnectable front differential.

Many of us (Me included) did this with great success.
I guess I was just tying to find out whether this had changed on the Gen 8. or whether it still works in exaclty the same way.

As I mentioned, I thought the mod was very worthwhile (especially as it only takes about half an hour and only costs you a switch and some cable). I'm a bit bemused that nobody that has upgraded to the new model seems to have attempted it.
Come on guys, one of you must have looked at doing this?
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby hayst on Thu, 10 May 2018 6:43 +0000

How did you get on with the mod, it is extremely useful to be able to drop in to low two wheel drive.
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby adamkberger on Fri, 11 May 2018 2:54 +0000

As mentioned earlier, the transfer case on the Gen 8 is controlled by the 4wd ECU and cannot be overridden. Gen 7's have a manual lever to select low range. Completely different vehicles.
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby Surfseeker on Sat, 12 May 2018 10:48 +0000

Yep, Adam has said it perfectly. This mod was possible on the Gen 7 due to there being a combination of a manually selected transfer case and the (separate) electrical ADD. This made it pretty simple to manually select low range but then simply interrupt the signal to engage the ADD.
This is going to be a far more tricky proposition with a system that is now fully comtrolled by the 4WD ECU.
There are many far smarter folk than me out there, but I can say that from my level of expertise (Not very bright but can lift heavy things!)...this mod is not going to happen anytime soon.
This actually echos the rest of my journey updating froma Gen. 7 to a Gen. 8
Gen. 7 (even by the standards of the day) was a fairly straightforwrd vehicle. Just about anything you did to it made it better and most mods were relatively easy (Even for a hack like me) to do.
Gen 8 is a whole different best. It is just so much better developed. So the modifactions seem to be less necessary but also a fair bit harder. Some, like this and the rear seat mod for example, may not be achievable...at least without being an abbsolute mission.
That being said. I absolutely loved my Gen. 7 and had it set up exactly as I wanted it.
But would I go back?
Nope.
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby Batman on Wed, 16 May 2018 6:15 +0000

Don't complicate things too much the 4x4 ECU must get a signal from the switch to do two things, firstly engage H4 or L4 and secondly to engage the ADD. Find the wire that powers the ADD, switch it and problem solved. Start by looking at the same wire out of the 4X4 ECU.
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby numberplate on Thu, 17 May 2018 6:52 +0000

These internal switches would also act as a limit switch so the motor's movements need to be taken into account. if you overdrive it you may bugger the plastic gears inside.
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby adamkberger on Thu, 17 May 2018 2:43 +0000

I never thought of limit switches. DL1 and DL2 could be limit switches to stop the motor from over running. If that's the case, all that's needed is a DPDT switch. I'll knock up a drawing when I get a chance.
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby numberplate on Thu, 17 May 2018 6:42 +0000

I cant confirm my theory Adam , i just looked at some internal images of these fitted to Tacomas and they look like a limit switch , attached to the pushrod ends.
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby clyde on Fri, 07 Sep 2018 1:58 +0000

Reading all the above points, and looking at the schematics, this is my summary on it. The ECU will operate the diff motor when 4wd is selected. As for the DL1 & DL2 switches, I'd guess that they would be limit switches to stop the driving of the diff motor when its at the limit.
Now the ECU is looking for confirmation of the ADD. I'm going to assume that this is through the 'ADD' input on the ECU (the white wire leaving from ADD on the schematic above). This wire does also feed to the ABS. But it is interesting to note that on models without the ADD fitted, the ADD input on the ECU appears to be not used, and the ABS is switched from an earthed switch from the transfer assembly. This switch is also providing a signal to the '4WD' input of the ECU.
So when I get the chance, here's the test I'd like to try:
1. disconnect the diff motor wires.
2. try 4WD; I'm guessing that the ECU will not be happy as it will see the 4WD input but not the ADD input, and signal a fault.
3. test again in 4WD but earth out the ADD (and ABS) input and see if the ECU now thinks that the vehicle is in 4WD.
4. If all is happy at this stage then try low range.

If this test works and there's no indication of faults due to lack of signals from the diff limit switches, then it would be a matter of a switch to operate a few relays to achieve the same thing. Hopefully include a bit more trickery to leave the standard rotary switch alone and just have a 2WD Low switch that only operates in neutral or brake on...
Watch this space!!!
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby numberplate on Fri, 07 Sep 2018 2:37 +0000

keep us posted thanks , i have not got around to doing anything about this as yet
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby rusty66 on Mon, 24 Sep 2018 12:51 +0000

Hi, are there any news on this? Quite interested if it works.
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby clyde on Mon, 24 Sep 2018 11:05 +0000

Sill in the pipeline. I've just picked up a new camper trailer so working hard to be ready for start of October week. Hopefully I'll be back in the shed after that!
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Re: Disconnecting the A.D.D on 2016 Hilux sr5

Postby nicebike on Tue, 25 Sep 2018 5:22 +0000

Batman wrote:Don't complicate things too much the 4x4 ECU must get a signal from the switch to do two things, firstly engage H4 or L4 and secondly to engage the ADD. Find the wire that powers the ADD, switch it and problem solved. Start by looking at the same wire out of the 4X4 ECU.


I think you blokes would be well advised to reread this post and actually try it, rather than creating all these complicated plots and theories :lol:
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