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.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 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.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 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.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 ?
So let me get this straight. There isnt actually a limited slip in the diff.. its some anti lock computer thing? Lol....sigh...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.
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.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...