Rear Diff Lock Anytime Mod 3rd Gen DEVELOPMENT

Yes
Disconnect diff lock coil throws code.

Disconnect lock feedback sensor doesnt generally throw a code, as it NO unlocked, and grounded when locked.

 

The 12 volts applied is only at 70% or 50% duty cycle. So 70% of 12v to engage, (8.4V), then 50% of 12V to maintain engage, (6V). if I read the post correctly

 

that looks like an easier solution than I had envisioned. I was seeing a voltage regulator and some feedback logic set-up on a little PCB

 

I usually overlook resistors as an option as I tend envision the traditional voltage divider network which is "inefficient", and the load affects the applied voltage.

 

That is my understanding yes.

The 70ish percent duty cycle seems to be a %set in the ecu logic.

The 50% duty cycle seems to be a current target so, so the duty cycle hunts a little to maintain the specified current.

Note, I dont know of any reason resistors wont work. I dont encourage ever putting 12v on the thing (dont know how it will like that). I dont know if they reduced current in the locked condition to minimize diff heat, or lock coil life, etc.

Resistors will definitely need to be power type. 100 watt power resistors are cheap and would probably be fine. But need to dissipate the 20 or 30 watts of likely constant heat without melting or overheating anything. Nice heatsink, or bolt it to the firewall maybe, or something else is probably recommended.

 

Found no elegant way yet. If you come up with something better, please post it up.

Best I found is if you wire a relay to cut the 12v input power to pin 46 of the skid control ecu, then ABS, VSC, and 4Wd mode changes are unavailable. They seem to come back as soon as you reapply power (per my memory). I doubt you will be able to kill trac or abs without also killing 4wd mode changes (at least temporarily)

 

Heat dissipation was a major concern in my initial thoughts. That and the load in parallel with the voltage divider resistor gets hairy. That's why I started thinking about a dedicated circuit with a voltage regulator and a current sensing resistor and differential amplifier, etc.... Thus leading to a circuit that is almost certainly overly complicated for the task at hand.
I may still pursue it as an academic exercise. But, as @Dragracer_Art eluded to, simpler is almost always better

 

I'll going to explore this from the micro controller option... I think at the end of the day, especially if we want to combine with 2 wheel low range, that will be the best way.

Something like this comes to mind....

https://www.amazon.com/SainSmart-Ad...+regulator&dpPl=1&dpID=51GF6ySFW0L&ref=plSrch

Voltage can be completely controlled. Amps is 2 with a peak of 3, do we know if that would work?

 

About 4 Amps (Toyota used to get it to lock, per my memory...)

 

Hi guys, I just found this thread, I've been wondering about a mod for this for a while. Great work doing all the research and putting the info together! It would be great to keep it simple and use relay logic to put this together but with the PWM that makes it much harder. In my eyes the existing PWM control gives need to a micro controller like an arduino. You pretty much need some sort of PWM controller anyway so why not use one with built in IO so you can spoof the outputs and ECU inputs. The drawback besides being complicated is I don't like to rely on software and cheap hobby boards for this kind of stuff though. If I end up grenading my diff out in the bush because of a arduino malfunction or software glitch that would be a major problem.

I know this is working in a different direction than the rest of the thread but I've got a little idea I would like to share. Perhaps take the locked ECU input and route it into the arduino, then you could provide yourself with feedback when you are in anytime mode. Not only would you get feedback but you would prevent the ECU from getting the feedback and throwing a code. You could use something like a DPDT switch to enable the mod that would switch the signal and control back to original wiring straight to the ECU. Then you would have to wire a second switch as a dry contact input to the arduino that would enable the actual locking action. With this option you could wire up a diff lock override light or take other ECU IO and play with them.

So to recap you have:
1) Mod Enable switch - this re routes all the ECU wiring into an arduino
2) Diff lock enable switch - this would start the PWM cycle for locking the diff


I might give this one a shot but before I do, I would like to hear some feedback. Maybe point out some flaws in my half baked plan before I waste a bunch of time on it. I'll draw a little wiring detail and figure out the exact details in a bit but for now I gotta get back to work.

Big thanks to the guys who started this mod out, very thankful for all the pinouts and great information here. I wouldn't be able to come up with ideas if it wasn't for you guys doing the legwork and finding all the info out.

 

This sounds much like the approach I have been working on with the exception of the Arduino. Although I use microprocessors and PLC's every day, I tend to shy away from them when I am working on outside projects I tend to shy away from anything that requires code. True digital logic when possible.
My approach uses a Carling DPST, {Off, On,(On)}, some typical passive components, a handful of P channel MOSFETS for switching activities, a couple of 555 timers, a NAND logic chip and a frequency to voltage converter. For the converter, I am looking at LM2907, but I'm not 100% sure at this point. Maybe an opto-isolator. I'm still investigating other options. such as current to voltage and use a coil to indirectly read the current to the diff.
I have the flow chart and block diagram all worked out I just need to sit down and work up the actual schematic. Then, work on an efficient PCB layout which will probably still be pretty tough since I am only using "easy EDA".

I haven't published any of my ideas on this forum yet. But I have everything right here, and if anybody is interested, I'd love to collaborate.

 

There have been others mentioned doing a microprocessor solution.
https://www.tacomaworld.com/threads...d-gen-development.537810/page-2#post-17338804
It really needs a microprocessor solution rather than electromechanical solution (And incorporate 2wheel lo also).

I would recommend designing it such that single power wire activates a multi pole relay and activates the anytime lock controller. Depower deactivates the relay and removes power to anytime lock controller.

 

I have to admit, I abandoned searching for solution that included 2lo when I found the thread about locking hubs for the 3rd gen.

 

Although not as elegant a solution, I convinced myself it would make circuit design for anytime rear diff lock so much easier.

 

I still think you guys are overthinking this.
if the only glitch that throws a code is an unplugged actuator... all thats needed is a resistor to spoof the ecm. You wouldnt need to be concerned about heat... because youre only using the resistor so the ecm sees a specific resistance and says "ok...the actuator coil is there, all is good"
The only other thing needed is a switched power supply to the actuator.
Traction control can be turned off manually in the overhead console.
Im probably (likely) oversimplifying it, but thats what I would try first if I ever find the time to mess with mine.

 

2 wheel lo is pretty simple electromechanical solution. But while in the 4wd harness it would be simple to incorporate it. (1 relay and a resistor)

https://www.tacomaworld.com/threads/lock-stock-and-2wheel-low-3rd-gen-diy-mod.536677/

 

Yeah, pretty straight forward.
But as is often the case, once you convince yourself of something, regardless of facts, it can be difficult to back track. Once I saw the benefits of the hub conversion it influenced my thinking going forward.
Also important to note, my circuit design approach is all based on having not actually been into that portion of the vehicle wiring harness yet. I'm just working against some descriptions and a few isolated schematics. So at this point, its all purely theoretical.

 

A resistor will complete the diagnostic circuit for an unplugged actuator. But, once the actuator is unplugged, a pulsed signal still has to be sourced somehow to engage the coil when you want the differential to lock.

 

I missed that post reading through the thread the first time, thanks for pointing that out I will follow up with that guy and see if he ever got anything going for it. I didn't see any posts here about success so I'm assuming the solution is still out there.

Now you recommend incorporating 2LO mod as well, is there a reason for that? It's not really something that has crossed my mind as something I need but if it's simple and I'm already messing about it probably wouldn't hurt to have more options. I haven't looked into it at all, I gotta do some more reading before I start messing around. It would be pretty cool to build a little control panel you could mount on the dash that housed all the mods. I know I'm getting a bit ahead of myself but then you could have a good spot to mount indicator lights too.

 

They probably use regular voltage for engagement and reduced voltage to possibly allow some slippage so it doesn't lock up solid like a spool. (hence the pancake design)
I'm willing to bet it will be fine with a steady 12v and will probably work better. (tighter lockup)
This can be via your own homemade harness, relay and toggle switch.
It appears to be a very robust 8-3/4" rear diff.

I will see what the weather looks like this weekend and will try fooling around with it if I can.

If you guys come up with a hi-tech wizz-bang solution, by all means, go for it. I'll certainly be on board... but until that happens, I'm trying to keep it simple.