You can keep your 03 TAC module and leave the TB alone. If this works out there will just be a little black box attached to the adapter harness.

 

I'll be waiting for this one!!! Put me in line FIRST!

 

Ahead of Holty, of course!!! LOL

 

Thats great.

Just out of curiosity: Are you using the reading from the 0-5v sensor on the TB, to feed both TAC inputs while altering one value enough to make it unique and keep it inline? OR Are you actually taking the 5-0v value from the second TB sensor and changing its value back into 0-5v range for the second TAC sensor?

 

I looked at circuits for both alternatives. The former option requires less components and I am not sure that there is a real advantage to either if you want to be able to retain your stock TAC module. Neither is 100% ideal. Unless you are willing to go into the TB and create split supply circuits, but that obviously defeats one of the primary goals(simplification of the 90mm swap).

 

Thats what I figured. Going with the second option would keep both sensors separate and somewhat keep GMs built in error checking system valid. That option would take quite a bit more work to accomplish though. I was working on the first option myself before the 02 TAC option was around. I made some progress at the time, but I didn't get it to work reliably. I'm glad you've made this much progress.

 

The second approach would require a couple of extra chips. Still not perfect due to the shared 5V reference circuit in the LS2 TB. The 03+ TAC modules are quite fussy though. Doesn't take much to trigger REP mode. Other checks like the expected airflow tables are also important. So it is wise to keep sane values in there.

 

Put it together on a custom mini circuit board and did a little more bench and road testing today. Had to do a little tweaking for slightly different specs on new components from different manufacturers. Working great so far. Nice smooth operation. Blade has full range, and no annoying high pitch whine from the TB.

An external supply is required(1 wire). I have been using the +5V ref to the A/C pressure sensor as it was close by[circuit 2700(grey)-Pin 45 on connector C1(blue) at the PCM]. Circuitry changes would be required to run this off a different 5V ref circuit or from 12V due to the different current/voltage values.

 

awesome man!! definatley interested in your results.

 

Nice.

With the sensitivity of the design referencing the additional +5 supply, have you been able to do any testing to see what conditions make that AC circuit vary its 5v reference? I mean, have you watched its value when driving with lights on, lights off, AC on, off, etc... I guess anything that might alter the voltage.