Lock, Stock, and 2Wheel Low (3rd Gen DIY Mod)

That is all this mod does, is disable the ADD. However on this truck the
ADD has an electrical motor and 3 position sensors. So to disable it and fool the computer requires a 4pole relay.

The motor has to be replaced electrically by a resistor, because the ECU is checking the resistance. The 3 position sensors on the ADD need their position faked. So 4 pole relay driven by a spst switch in the dash.

It really is pretty simple...

 

Ok, cool. What would happen if you didn't try to fool the computer but simply had a switch to disable the vacuum switch relay. What would the ECU do if it's checks failed? Limp mode? Warning light? Can't get into low range?

 

All this data is based on my 2017 4x4 TRD OR. The failsafe charts indicate similar on all, but no guarantee.

If you just cut DM1 or DM2 with a switch, when you start the truck, or change any 4x4 setting on the selection dial, the truck will notice the resistance is wrong on DM1-DM2 and will store a code, display a dash error, and lock out ALL 4x4 mode changes. (computer will assume that wiring has been cut, and failsafes)

If you disconnect DM1 or DM2 from the motor, and short it with a power resistor, then the ECU will see the correct resistance. Therefore, the ECU will not notice an issue on startup or initially on 4x4 mode changes. However after approximately 2 seconds after the driver requests a change from 2hi to 4hi, the computer will realize that the position feedback wipers have not properly changed positions. Computer will display dash error, and lock out all 4x4 mode changes. (computer will assume that the front ADD has jammed and won't move, so it will failsafe).

So, in short, if you do as you ask, the computer will prevent any further 4x4 mode changes until you power cycle after the fixing the 'wiring issue' .

That answer your questions?

 

Note, forgot to mention, the third gen doesn't have a vacuum switch relay. I think 1st gen did.
No vacuum used at all.

 

OK, so unless we fool the (dad-blamed) computer into thinking the ADD is functional, the system will abort 4x4 requests and we'll never actually get into low range. I really wish Toyota SW engineers would implement a 2-low option. It would be an absolute piece of cake. Sigh.

 

Based on my experiments, yes, absolutely.

 

@BigWhiteTRD, you mention a 2nd gen mod like this? Do you have a link, I can't find it? Thx in advance if you do

 

End of this thread, talk goes from DIY, to automated.
https://www.tacomaworld.com/threads/2wd-lo-mod.195424/

And
Buried on this thread.
I am using phone now, so that makes it harder...

https://www.tacomaworld.com/threads/heated-mirrors-kit-interest-update-thread-pic-heavy.377840/

 

Awesome. Thank you for your efforts

 

I’ve read through the thread, has anyone successfully done this on a Manual Trans?

 

There have been no reports of anybody else trying this mod, manual or auto. (But as you indicate, my test truck was auto). Schematics are identical except tiny difference in start clutch cancel switch, per my memory.

In case anybody is planning on trying this DIY soon, we might have located connectors to make this a plug and play mod. (Still be a DIY mod, but now much easier to undo the mod, etc). Haven't written anything up yet, as I am trying to get the effort together to test out the 2lo + lock anytime mod, but if somebody is ready RIGHT NOW to try plug and play 2lo DIY, let me know.

 

Someone in another thread said that they did it, but never posted here.

Oh man! Life has been a bit busy. I was talking about the connector issue with @Hoangde . He gave me a source for the 40pin. I am sorry that I didn't pass it along.

 

Yes there is a significant difference in the two. The second gen 8” e locker used an external motor to move a shift fork in the housing. Motor ran till shift fork was in the locked position then shut off. Same operation to unlock only reverse rotation in the motor.


The third gen e locker is a electro magnetic coil with I believe a pull in and a hold in winding or at least a voltage drop on the hold in. No shift for to move just slides the locking dogs in the housing. Image is a representation not the actual.

 

Yep
See all we learned so far about the new elocker, and its operation here
https://www.tacomaworld.com/threads/rear-diff-lock-anytime-mod-3rd-gen-development.537810/

 

God yes please, someone. I am so on board with this. I agree that it would be TOO easy for this to come from the factory. I even talked to my cousin who is a mechanical engineer at PennState that works a lot with vehicles. I will be picking his brain a little more this weekend and may take this with me to see what he thinks.

 

To reiterate to people, connectors to make this a DIY plug and play mod, rather than cutting the harness are believed to be located. I haven't tested the connectors yet, so i dont want to say for sure yet, but they look right. More data in the anytime lock thread...
https://www.tacomaworld.com/threads...d-gen-development.537810/page-8#post-18589486

I am working on making a combined 2whl low and anytime rear lock mod, as they are in the same connectors. But getting motivated is hard.... but anybody who wants to do 2whl low as a plug and play DIY, it is probably now possible and not too hard...

 

Would love this ... 1 lane driveway on a slope uphill to the back ... backing trailers in is frustrating in 2wd - I have thrown it in 4LO when pushing heavy trailer in.

And yes - too bind-eee

 

I finally installed the @mesojdm LSP7 this week. I've only had it since May!

So, I am about to order some switches for it. If you do make a PnP 2Lo device, will it work like the 2nd Gen one where you pause between 2Hi and 4Hi to let it start the logic or would we still need a button like your current design?

Also, I know you are basing this on your OR in combo with the locker mod. Will a single PnP option work for us suckers that don't have an OR or Pro? Or, do we get a PnP locker with it?? Ha!

Thanks!

 

Separate switch, no elegance of the 2nd gen solution. Just too hard to do electromechanically, and (although I played with them) I am not good enough to do a raspberry pi or similar microprocessor solution.

Dont know on the combined module for sure. A combined module could be used on a sport/sr, and just omit the lock anytime switch. Alternatively, the circuitry for the locker could also be omitted for cost savings...

Sitting at work with broke AC makes it hard to feel too positive about the whole idea frankly...

 

Thanks! I don't mind either way. I just wanted to get all the buttons at once (2Lo, garage opener, front light bar in the future, and rear aux).

I would try a hammer. What's the worst that could happen?

No rush on the mod. Maybe the cooler weather in January and February (and all the tourists) will help?