TTORA Forum banner

1 - 20 of 205 Posts

·
Registered
Joined
·
44 Posts
The 4Wheel ECU is above/behind glove box. I see a small gray wire but am looking for someone that has done the job on the 2005. Will probably try to figure it out with an ohm-meter or locate/buy a schematic. Someone out there surely must have figured out this mod. Any info appreciated.
 

·
Registered
Joined
·
196 Posts
bill4x4 said:
The 4Wheel ECU is above/behind glove box. I see a small gray wire but am looking for someone that has done the job on the 2005. Will probably try to figure it out with an ohm-meter or locate/buy a schematic. Someone out there surely must have figured out this mod. Any info appreciated.
I have looked into this a bit. The ECU and 4WD computers do not appear to "talk" to each other the same way they did before (which was the grey wire). I have not been able to determine how to work out this mod in the '05, but I have not given up yet.
As for some schematics, here is from a previous post of mine:
Yes on the wiring diagrams. Go to http://www.nowwgasa.net/ and click on the "Vehicle Buildups" link then go to the '05 X Runner "full info..." link. They have the wiring diagrams there in a set of zipped .pdf files! I don't know if it is ligit, so make your own call.
 

·
Registered
Joined
·
27 Posts
I have narrowed it down, just dont have the time yet to figure it out.

If you open the zip files and check out the circuits file folder, open abs_trac_vsc... and scroll to page 3. This shows where the wiring goes to the transfer indicator switch (I believe how the vehicle determines if it is in 4lo)

Then if you look at the file called reardifferentiallock_2wd, scroll to page 1 and 2 for the wiring diagram of the rear diff lock and sensor. Also, scroll to page 3 for a description of how the system controls the diff lockout.

I think we are getting a lot closer.
 

·
Registered
Joined
·
44 Posts
Tacoma05LockerMod

Thanks for the great info and looks like I don't have to waste $100+ on schematics now. Am studying them, boy sure gets complicated fast. Notice that in the 'reardifferentiallock_2wd.pdf', 4Wheel ECU pin 7 is grounded, but in the 'multimode4wd_differentiallock.pdf' it is not shown. Wonder if this pin is overriding signals normally there on 4wd's to allow lockup on the 2wd ?
 

·
Registered
Joined
·
196 Posts
bill4x4 said:
Thanks for the great info and looks like I don't have to waste $100+ on schematics now. Am studying them, boy sure gets complicated fast. Notice that in the 'reardifferentiallock_2wd.pdf', 4Wheel ECU pin 7 is grounded, but in the 'multimode4wd_differentiallock.pdf' it is not shown. Wonder if this pin is overriding signals normally there on 4wd's to allow lockup on the 2wd ?
I have been looking at the overall schematic. On 19-1 they show the 2H-4H-4L switch connecting to diodes and two wires to the 4WD control ECU. The signals work thus: Pin-8 (GR), ground = 2H; Pin-8 and Pin-15 (L), ground = 4H; Pin-15, ground = 4L. I assume that those two pins have an internal pull-up to logic-high and the combination of ground on the pins tells the 4WD computer what mode you are in.
The four lines used to lock and unlock the differential all come directly from the 4WD computer.
I am trying to figure out the effects of T13 (transfer indicator switch) on the system.
If we bang enough heads against the desk, maybe we can figure this thing out. I am also trying to figure if I modify this thing to allow me to UNLOCK the 4L at any speed. Boy do I miss the manual transfer case!
 

·
Registered
Joined
·
44 Posts
I'm thinking they may have done some of this to prevent us from doing a simple mod to lock in 4 Hi. Looks like it's been made to where all the inputs will have to be faked into thinking it's truely in 4 Lo which results in the main computer adjusting shift points etc... just like the blue wire mod. Still wondering what the grounded pin 7 which appears on the 2 Wheel rear diff lock schematic does and that the key may be understanding the difference between the 2 wheel and 4 wheel ECU wiring. Let me know of any more info as it looks like you are making good progress, but my gut feel is that we may be into simply wiring a manual switch setup that provides inputs to D10 Diff Lock shift actuator assembly. Hmmm ?
 

·
Registered
Joined
·
196 Posts
Here is how to do it (kinda)

bill4x4 said:
I'm thinking they may have done some of this to prevent us from doing a simple mod to lock in 4 Hi. Looks like it's been made to where all the inputs will have to be faked into thinking it's truely in 4 Lo which results in the main computer adjusting shift points etc... just like the blue wire mod. Still wondering what the grounded pin 7 which appears on the 2 Wheel rear diff lock schematic does and that the key may be understanding the difference between the 2 wheel and 4 wheel ECU wiring. Let me know of any more info as it looks like you are making good progress, but my gut feel is that we may be into simply wiring a manual switch setup that provides inputs to D10 Diff Lock shift actuator assembly. Hmmm ?
I worked through the schematics a bit more last night and I can conclude the following: the simple "grey wire" mod is no more; the 2WD and 4WD models likely have different "4WD" ECUs; to make the locker work in any other mode, we will have to come up with a modified (possibly plug-in) addapter to rewire the harness between the locker and the 4WD ECU.
My thought is that the 4WD ECU will have to be bypassed with a custom setup. This may not be too hard.
Working from the 2wd locker description, this is how I think the 4WD locker works (you will need to reference the schematic to follow this):
- Switch the RR Diff Lock on (with SPD in correct logic state, and 2-4 and LO in correct logic state, and maybe even the MTN or N in the correct state), causes current to flow from 4WD fuse to IG (pin 5), out M1 (pin 2), through the Diff Lock Shift Actuator Assembly (DLSAA) motor, into M2 (pin 1), out RLY1 (pin13), through the DLSAA limit switch, to GROUND.
- Eventually the diff locks and the DLSAA limit switch will remove the ground connection from the motor (power connection is still there?).
- Switch the RR Diff Lock off, causes current to flow from 4WD fuse to IG, out M2, throught the DLSAA motor, into M1, out RLY2, through the DLSAA limit switch to GROUND.
- Again, the diff lock eventually disengages and the DLSAA limit switch will remove the ground connection from the motor.
- When the diff lock is engaged, the Transfer Indicator SW is closed. This will ground the Rear Diff Lock LED (turn it on). While the diff lock is waiting to engage, the RLP (pin 20) line on the 4WD ECU can pull the same line to ground in order to flash the LED (waiting to engage, it knows this based on the RLY1/RLY2 status?).

So the big question is: are the M1 or M2 lines hot all the time? If so, I can invision a custom setup that will route the power to the DLSAA motor with the flip of the diff lock switch. Remove the connection to R from the diff lock switch and the 4WD ECU just thinks that you never like to engage the locker. Remove the connection to the RLP and you even get the indicator LED to work! Route the hot output line (M2?) to a relay (DPDT) that works with the diff lock switch and pushes the power to the proper side of the motor and have the ground from the DLSAA limit switch work with the same relay and wha-la, a locker that works whenever you want it to. The best part is that the ECU doesn't know about any of the changes and never will see the actuation of the locker.
To get this to work, I need to check out the state of the lines running between the locker and the 4WD ECU when it is not locked, when it is trying to lock, when it is locked, etc. That way I can be sure that my mod will properly route all of the signals and not interfere with the rest of the 4WD ECU operation.
How is that for a full post? ;)
 

·
Registered
Joined
·
44 Posts
This sounds good - you can become rich and market the thing. One of the reasons I bought the truck was after I found out the locker could be moded to lock in 4-Hi (assuming the gray wire mod would work). Always wished it just had a stout limitied slip diff. option, not the fake setup they have now on the Sport versions using antilock coupled with computer. Keep us posted.
 

·
Registered
Joined
·
196 Posts
No update yet. Sorry. Life keeps encroaching on hobbies.
 

·
Registered
Joined
·
297 Posts
bill4x4 said:
This sounds good - you can become rich and market the thing. One of the reasons I bought the truck was after I found out the locker could be moded to lock in 4-Hi (assuming the gray wire mod would work). Always wished it just had a stout limitied slip diff. option, not the fake setup they have now on the Sport versions using antilock coupled with computer. Keep us posted.
So let me get this straight. There isnt actually a limited slip in the diff.. its some anti lock computer thing? Lol....sigh...
 

·
Master "Yota"
Joined
·
431 Posts
scottnmos said:
So let me get this straight. There isnt actually a limited slip in the diff.. its some anti lock computer thing? Lol....sigh...
No you can get a real limited slip. The TRD sport models have a real limited slip, the offroad models don't they have a locker, and all other models have an open diff. All the models can be ordered as an option with the VCS package. For the non sport models like the TRD offroad it uses brake manipulation to simulate a LSD. The package also includes down hill assist, hil start assist, and VSC.
 

·
Premium Member
Joined
·
12,934 Posts
I looked at the schematic for you guys. It looks just like the same actuator used in earlier years. Even the pin numbers are the same. As such this mod should work just as well for the 2005 as other years. It's in the Tech/FAQ section here too.

http://www.norcalttora.com/~dick/Writeup%20Stuff/toyota_elock_control.pdf

Edit,
I forgot to add this link for a switch and whatnot all done up if you want to go that way with it. Personally I don't like the looks of this one, I used an illuminated rocker for mine but some folks find that buying something already put together to some extent a lot easier. If you look around you should be able to find the right kind of switch that would fit the hole that the factory switch sets in. If you used relays, you could even use the factory switch and just unplug that troublesome locker ECU thing.

http://www.12voltguy.com/catalog.0.html2.0.html
 

·
Registered
Joined
·
27 Posts
Well... thats an option I've never seen - I may get desperate.

I just liked the grey wire mod since it was already wired and it had the speed/load sensor built in, you just had to bypass the 4-lo signal coming from the t-case.
 

·
Premium Member
Joined
·
12,934 Posts
I think that speed input was about half the problem people had with the elocker. This way you can lock it up when you want to.
 

·
Registered
Joined
·
196 Posts
Dick, nice write-up. I was not aware that anyone had worked out a circuit that completely bypasses the 4WD computer (kinda like I described earlier). I intend to do this, just so I have full control of my locker--rather than rigging the computer into thinking it was in control. Your method, a good DPDT relay, use of the original switch and maybe the original indicator looks like my ticket.
 

·
Registered
Joined
·
196 Posts
tbrown said:
...The package also includes down hill assist, hil start assist, and VSC.
Only on the automatic. Us stick guys have to figure out the hill stuff on our own. ;)
 
1 - 20 of 205 Posts
Top