As Dick Foster over at TTORA described, if the Diff lock was completely disconected from the computer and wired up as shown, you would be using the limit switch as the ground shut off switch when activating/deactivating the e-lock. You can manually activate the actuator this way, and it will disengage the motor automatically.
The problem is that the computer still tries to read the sensor/switches to verify it's off (in other modes). Not really a problem on '04 and earlier because they have a seperate computer for the 4WD and the Diff lock. 2005+ are combined into one. This problem becomes obvious when you disconnect the switches, actuator, etc and the 4WD indicator lights go haywire (as a few other 05+ Tacoma owners have encountered).
Solution: Wire the 4WD computer wires you will cut in their default "diff lock "off" position. You must complete any circuits the computer reads to verify the status of the diff lock as "OFF". Then you can Use the actuator independently (manually) of the computer.
********
I'm sure you all know this will also not disable ABS, VSC, etc if you bypass the computer and activate the diff lock manually. Also no "safety" features to keep you from accidentally switching it on at unsafe speeds.
Already mentioned my idea with the second computer...
********
Thanks to Dick Foster from TTORA and you for posting the link. You can defeat the ABS and VSC by removing power from the ABS 1 and ABS 2 fuses either via a switch, or just pulling the fuses when out playing.
Thanks to Dick Foster from TTORA and you for posting the link. You can defeat the ABS and VSC by removing power from the ABS 1 and ABS 2 fuses either via a switch, or just pulling the fuses when out playing.
Your welcome!
I just found and posted the info...
I guess I should mention this diagram was not specifically designed for an 05+ Tacoma. It was originally designed for adding an aftermarket locker (with similar actuator system as the Taco) or for 04 & earlier owners that wanted a manual locker switch. The actuator system on 04 & 05+ Tacos is VERY similar. It's the computer system that is different, so it should work (with a few wire modifications to the computer).
I won't get to try it for a few months until I get my truck! Let me know if it works out.
Back at it again... So by removing power to the ABS 1 and ABS 2 fuses we can disable ABS and VSC, but all the idiot lights come on and after about thirty seconds the VSC beeper starts wailing. Yeah I know, just remove the beeper from the circuit board and shut up about it right? That's an ok solution for short term playing in the mud, but it still leaves the rear locker problem. That was solved already by Dick from TTORA, and while I am positive it would work, I don't really like the solution. Again, I would like to have a single switch that disables VSC, ABS, and allows the locker to engage. I tried to trick the computer by grounding out pin 17 connector F-13 wich according to the schematics should have a yellow wire with a black stripe connected to it, but strangely doesn't. So how does the 4wd ecu know that 4LO is engaged? Argggh.
I'm with you tacosupreme, I wish it were more simple. I've looked over the wiring diagrams too and haven't figured a better solution. Hopefully someone will come up with an easier way soon.
I tried to send the 4LO signal straight from the T-case today, and it still didn't work. The switch has to be in 4LO, then when the T-case sends the signal back to the 4WD ECU wich in turn relays it to the main ECU disabling abs and vsc. I guess I will have to find a DPDT switch somewhere and just go with Dick's idea for the locker and switch the abs and vsc off on a seperate switch.
See guys.... here's the problem. The computer reads the current t-case position (2HI,4HI,4LO) from the transfer switch and the limit switch (combo of both). It uses these as an indication of what position the t-case is in while shifting to/from 2HI,4HI,4LO. Not only does this limit the ability to enage the e-lock, The 4WD requires this for proper shifting, so you CANNOT gound something out to get the e-locker to engage. If you try, the 4WD will not work correctly and as a result won't enage the e-locker either. It's been tried and tried, and ALL failed!
I'll elaborate a little more... the e-lock light (in the dash) is a manually engaged light that comes on when the e-lock engages and grounds out the switch. However the 4LO indicator light comes THROUGH the computer after it recieves a signal from the 4LO transfer inticator switch. It uses it to sense it is in 4LO, for the e-lock as well as for the lights, but is used in conjunction with the limit switch to know what mode it is shifting from (and is a way to check for errors or shifting problems as well). Understand why it won't work now?
YOU MUST either bypass the computer altogether to enage the elock manually, or you must add a second computer from a pre-runner to control the e-locker (with the OEM swtch) independently of the 4WD computer (2HI,4HI,4LO). This way uses the same switch and still disables ABS, VSC, etc.
The thing with '04 and earlier models is it has a SEPARATE control untit for the locker. You do not ground the actual 4WD conuter signal, you are grounding the signal that goes to the E-locker control unti which allows it to engage. We do not have the luxury of that second computer which is why a simple grounded wire WILL NOT WORK!
So basically, either way, there is no "quick and easy" fix. You will have to do some serious rewiring to get it to work!! Either by adding a second computer or by completely rewiring up a new switch AND a second to disable ABS, VSC etc. (If you want that)
I have provided the schematic for the switch. I have not found anyone willing to try my idea and spend the $300(+/-) for the computer to wire the second one; so I won't bother with a schematic until someone wants to consider it. However, if somebody wants to buy me the truck I'll do it myself!
The thought just occurred to me, that the actuator system on the '05 and pre-'05 Tacomas is similar. (computer systems are different though) You might be able to use the e-locker control unit (instead of a new prerunner 4WD ECU) from an '04 to control the locker on an '05. Would probably be cheaper than a new '05 4WD computer.
I'd have to look at the scematics more closely, but there is no guarantee that the control unit will communicate with the ECU and skid control unit the same way as an '05 model. May be easier than a complete rewire job though. I'll have to look into it.
Looking at the '04 & '05 schematics for the last few hours, I've come to the conclusion that you CAN use the Differential lock ECU (separate unit from the 4WD ECU) from an '04 & earlier Tacomas on an '05 to enable the Differential lock. It would be slightly simpler than adding a second '05 prerunner computer, but seeing the diff-lock ECU from an '04 is an older unit and probably more available, you can probably get it cheaper, and it will work essentially the same way as a prerunner computer. If you can find one at a junkyard or something with part of the wire harness attached, I can walk you through it (this is the same computer under the driverside kick panel, used for the 04 & earlier "grey wire mod".).
On a side note, I also noticed something else I didn't notice before regarding the '05 ABS/VSC TRAC...
There are actually 3 wires coming from the skid control unit to the 4WD system. I previously only noticed 2. One goes to the ADD actuator, one to the Transfer indicator for 4LO, and the 3rd (which I just noticed) goes to the Transfer indicator switch for the diff-lock. Don't get too excited... this doesn't mean you ground it and the e-lock will work. This DOES mean that the skid control has 2 inputs to disable VSC TRAC & ABS. ABS apparently still works in 4WD (incl trac control), but the VSC (engine control) does not. When the diff lock is engaged it also disables ABS in addition to VSC, which means a separate control unit JUST for the diff lock (just like on the '04s) will still disable the VSC, ABS, etc without doing extra tinkering with the 4WD computer. Means you can also add in an extra switch that will ground the wire going to the "diff-lock indicator switch" to disable VSC & ABS without removing fuses. (nice to know)
VSC=Vehicle stability control, or the doohickey that applies braking force to the wheel that is slipping. Tonight I tore the dash apart and removed the VSC buzzer, and just the ABS 1 fuse, wich still disabled abs and vsc. I took a drive to the north forty on base and wrung her out on a nice tight concrete course, and I lost all brakes. Not normal brake fade as is to be expected, I mean stand on 'em like they owed you money and nothing, zip. I could smell toasted brake pads (or maybe clutch). I popped the fuse back in and they worked fine even after a few more laps around my homemade track. The moral of the story, DO NOT DISABLE ABS!!!!!! It scared the crap out of me, and I am glad I was quick to grab the E-brake or I would be buying a new winch bumper sooner than I had wanted. Good work on the mod, but I am kind of skeptical. I just wish we had circuit board 'prints to really analyze the complete circuit. I know it seems like I am a dumba$$, but I repair the computers that guide missiles to their targets, thermal night visions sights, and laser rangefinders for a living and I know my way around schematics, there is just a lot of info missing.
VSC=Vehicle stability control, or the doohickey that applies braking force to the wheel that is slipping. Tonight I tore the dash apart and removed the VSC buzzer, and just the ABS 1 fuse, wich still disabled abs and vsc. I took a drive to the north forty on base and wrung her out on a nice tight concrete course, and I lost all brakes. Not normal brake fade as is to be expected, I mean stand on 'em like they owed you money and nothing, zip. I could smell toasted brake pads (or maybe clutch). I popped the fuse back in and they worked fine even after a few more laps around my homemade track. The moral of the story, DO NOT DISABLE ABS!!!!!! It scared the crap out of me, and I am glad I was quick to grab the E-brake or I would be buying a new winch bumper sooner than I had wanted. Good work on the mod, but I am kind of skeptical. I just wish we had circuit board 'prints to really analyze the complete circuit. I know it seems like I am a dumba$$, but I repair the computers that guide missiles to their targets, thermal night visions sights, and laser rangefinders for a living and I know my way around schematics, there is just a lot of info missing.
I agree there is allot of missing info... the thought had also occured to me to analyze the circuit. I'm sure the ground (L4 indicator switch) could somehow be bypassed on the circuit board, but that would be way more complicated for your typical DIY'er.
In responce to disabling ABS... I am not referring to removing a fuse and diabling the entire system. That disables the safety features and I agree that is dangerous. (remove power from the assisted brakes and they don't work). However, the diff-lock has a built in feature that disables ABS & VSC when it is engaged, but still leaves the computer in control of the system (brakes still work). This occurs when the Diff-Lock indicator switch is "on" and grounds the wire. If you disable the ABS using the same method the computer does with the diff-lock engaged (grounding a wire) you should be fine since there is still power to the braking system (and only the anti-lock portion is disabled).
Might be a reason the diff-lock AND Auto-LSD is only to be used to keep a wheel from slipping, at LOW SPEEDS, and then dis-engaged after you get "un-stuck." (according to owners manual) Guess that would negate any reasons for wanting/needing to perform a "grey wire mod" on '05+ Tacomas anyway, now wouldn't it?
Off-road applications are much different than your tight concrete course, which is why it's only supposed to be used in L4! Enabling it in 2H & 4H would assume a responsible person would only use it (therfore disabling VSC/ABS) for off-road conditions within the drivers ability to control the vehicle.
*Note to wannabe DIY'ers... know what your are doing FIRST. Screw with the wrong wires and you F'd!*
Back to the drawing board...
A)how does the ECU know 4LO is engaged, specifically what pins on what connectors get what voltage
B)how can we send false signals to those pins without disrupting normal operation
A+B=2HI Muddin'
Re: Locker mod?
no problem!
Linear Mode
