Rear Diff Lock Anytime Mod 3rd Gen DEVELOPMENT

Awesome work! I'll be happy to help with any testing. I'm no electrical genius but I'm willing to help out. I've been wanting to do this since I got the truck

 

Exciting! I'm looking forward to the end result here. I know myself and many others would be willing to pay a decent price for a finished product that is plug and play.

 

Following...

 

So do you think Toyota put any thought at all to purposefully making anytime lock difficult or is it purely a byproduct of trying to have every safety net possible for normal operation? If we still need someone to crawl around their truck reading PNs off of connectors I will do that. I am not an engineer but I do have a multimeter and can test voltages and whatnot on my '18 OR as well.

 

@Negra_Motaco

 

Sub'd. Loved this mod when i had my '99

 

I doubt it was setup to be intentionally hard. I think it is just the byproduct of changing designs and giving ECU full control. Once you make that decision, it is cheap to have the coders include a bunch of fail-safe checks, current and resistance monitoring, etc.

I dont know of any need now for crawling in truck. My best guess is:
Next step is I (or someone else) fabricate a circuit like I drew up previously in this thread (or something better that is suggested by someone), determine settings for PWM controller to simulate the ECU output, stick it in the truck, and try it.

I think I have all the parts now, but this isnt high priority for me. (I need to get some shit done I promised like a year ago at least). But I still fully 100% intend to keep pressing on and get it built up at some point if nobody else does it before I do

 

Word. I'm really just interested in being able to lock it in 4hi for snowy days. I haven't actually had the chance to try a-trac yet so maybe that will be enough.

 

If you're talking about locking the rear for street driving that's a horrible idea. You're risking sliding the rear during a turn and possibly losing control. You want some drivetrain slip on a slippery surface road.

 

I ordered connectors to build a piggy back circuit right at the pumpkin for this project. I thought it would’ve been easier to test and debug there rather than at the ecu. Let me know if you want the part numbers. I got busy on another personal project so I couldn’t begin this one.

 

Agreed -in light snow or at speed. I had an old jeep with lockers before the Tacoma. But where I live, during a good snow storm there is no "road" left. Last year we got a huge snow storm and driving home from work I saw more than 30 vehicles in ditches or stuck in snow drifts on the road. Helped a couple people out but it just got ridiculous. Maybe a-trac would have been enough to get through it. We shall see this year (especially with stock suspension and tires).

Either way hooligan things (off-road) are fun with a locked vehicle.

 

Did you get connectors for the lock coil and for the separate lock feedback connector?

From my tests, when you use an override to lock the coil, but leave the lock feedback connected to the ECU, the computer gets pissed off after a minute. (And locks out 4wd mode changes, requires engine power cycle to get mode changes back). I had the same thought you have originally and just splice into the two coil wires, so I did some simulations here
https://www.tacomaworld.com/threads...mod-3rd-gen-development.537810/#post-17337110

From tests on my truck, if you manually apply current to the lock coil and force it to lock without ECU command without disconnecting the feedback, ECU lockout happens in a minute or 2.

So that left it as cutting into both coul power and the feedback...(which is still doable as 2 separate connectors at the ECU or the diff) but I assume that is the same basic circuitry as I drew up in post 77. (Obviously if someone converts that poorly designed circuit into a better designed single circuit card or raspberry pi or something that would be much nicer)...

(Going to that step is 100% past my current expertise)

 

Sub'd

 

Correct! I got both. This was the cheapest place I found.

TS 2 type male connector side Capra Kit M090WP-TS/2P090WPK-TS-M
https://global.rakuten.com/en/store/auc-hi-1000/item/2p090wpk-ts-m/
Price 440(JPY) x 2(#) = 880(JPY) (Tax incl., Delivery Fee excl.)
----------------
2 p 090 type TS waterproof female Terminal side Capra Kit / 2P090WPK-TS-F
https://global.rakuten.com/en/store/auc-hi-1000/item/2p090wpk-ts-f/
Price 440(JPY) x 2(#) = 880(JPY) (Tax incl., Delivery Fee excl.)
----------------
090 (2) series 2 P female Terminal side Capra Kit-gray / 2P090WPK-YZ81207526-F
https://global.rakuten.com/en/store/auc-hi-1000/item/2p090wpk-yz81207526-f/
Price 550(JPY) x 2(#) = 1100(JPY) (Tax incl., Delivery Fee excl.)
----------------
2 P 090 (2) series male connector side Capra Kit-gray / 2P090WPK-YZ81207526-M
https://global.rakuten.com/en/store/auc-hi-1000/item/2p090wpk-yz81207526-m/
Price 550(JPY) x 2(#) = 1100(JPY) (Tax incl., Delivery Fee excl.)

 

Cool
I ended up with ecu ones at about $30 US with shipping, so that definitely looks a bit cheaper (fewer pins, so makes sense)

 

Applying 12v may work
I can guarantee that toyota did not apply 12v ever to that coil.
They apply reduced voltage to the coil, different for locked or unlocked. See early posts.

I dont know what 12v-14v will do to it..

 

Glad I found this thread, not sure how I missed it first time around as this has been on my list to sort out.
An all in one harness and switch or two with relays would be great, if this gets worked out.
Keep us posted and thank you all for your efforts!

 

Yeah, sorry to say haven't made progress in 2 months, just haven't gotten the time into it...

 

I'll give it some thought and see if I can contribute to the thread.
Looks like we know most of what does what for wiring and just need to configure something to test?

 

Yep.
I think time for some tests.
Alternative solutions are always a possible though, such as using resistors in lieu of pwm, skipping the two different powers (locked vs unlocked), and simplifying the circuit by removing the normal ecu locking method. (Makes it much simpler)