The first thing was to graft the Legacy TCU onto the GL-10 harness. It's quite straightforward - I basically matched up the wires using the wiring diagrams. There are a few differences, like the "1 hold" switch, but these things aren't needed once the paddle shift is in place. The Legacy also uses a atmospheric sensor input which I left disconnected. The tach input to the Legacy TCU is 0-5V where as the GL-10 TCU is right off the coil. I initially hooked it straight up and it worked, however I wasn't really happy with it so I used a zener diode and a resistor to clip the signal.
Apparantly the Legacy 4EAT has a stronger high clutch, as initially the 2-3 shift was pretty slow. The transfer clutch has changed as well. To resolve the 2-3 shift problem, I modified the maps in the TCU ROM to make the 2-3 shift faster. This solved that problem.
Initially I modified the maps for the transfer clutch; this made the AWD work again, but it wasn't so great. Sure, it worked as well as it did with the GL-10 TCU but there was a lot of room for improvement. There was a delay in engagement, and it sometimes spun the front tires on takeoff. I decided to upgrade the Duty C solenoid/valve body in my 4EAT to a Legacy unit, along with the orifice plate right behind the Duty C valve body. There were obvious differences in these parts, it seems like it is designed to flow much more fluid volume to the transfer clutch unit. I also replaced the friction discs while I was in there. It's a tad grabby now, but it works much better; I'm back to using the original Legacy TCU transfer clutch maps in place. I'm sure the clutch plates just need to break in a bit, as the cluch was pretty tight when I put it back together.
The TCU was modified by soldering a socket onto the circuit board. I was going to use a different Legacy TCU but it had no holes to solder the socket! I'm not sure what year that TCU was. After the socket is in place, there is a 0-ohm resistor on the bottom of the board that needs to be moved to enable the new socket. The ROM chip I am using is a SST27SF512; this EEPROM is easily reprogrammed without a UV eraser.
The paddles are just bent metal rods that I tack welded to some switches. They work pretty good. I made a small metal frame that attached to the steering column; the switches screw down into that. The paddles use the "manual" and "power" button inputs to the TCU. The paddle code will protect against overrev on downshift, upshift at redline, and downshift to 1st when stopped.
My most recent modification is a DCCD knob. It's a six position rotary switch with FWD, 75%, 100%, 150%, 200%, 4WD settings. It still allows the TCU to calculate the transfer clutch value but it then it modifies it depending on the knob setting; 100% would be stock, 200% would be twice as aggressive as stock, etc. The DCCD knob switch has some 1N4001 diodes wired in series between each pole. The FWD switch pole is attached to ground and the common is attached to the atmospheric sensor input. FWD=0V, 75%=0.5V, 100%=1V, 150%=1.5V, 200%=2V, 4WD=2.5V. If the switch is disconnected the code defaults to 100%.
Edited by presslab, 13 December 2008 - 12:27 AM.