This posting will deal with ECM side of wiring harness. A simple TBI wiring diagram can be found here:
Regarding 3rd connector - I have couple of questions - please see my list below:
3rd Connector ECM Wire Function
A A9 white/black ALDL diagnostics enable
B A5 brown/white SES light (pulled to ground by ECM)
C Empty
D A7 tan/black TCC/shift indicator (not used with std transmission)
E To RH injector, red=12v keyed power?
YES, connect to 15 Amp ECM Fuse #1 via separate relay – more on this later
F A6 pink/black 12v ECM Fuse #1 Hot in RUN/START
G Empty
H C2 Brown To air diverter valve connector.
You can ditch it if you are not using AIR pump.
J C9 Purple/white crank input needed for anything? YES
K B10 orange/black Park/neutral... this is empty on ours, had no wires coming out. OK
L ????? Purple RH o2 sensor, prpl. Not hooked up.
Does go down into engine bay? Can you find the other end?
M A10 Brown VSS, brown. Did this go to the buffer under the dash?
(Yes, it went to DRAC module) But now tie to one of the two wires that will connected to after market VCC module, the other to ground
N ????? black/white Ground
P red-white Fuel pump relay, red/wht
(Which terminal of Fuel pump relay???)
R A8 Orange ALDL data
Also have a light blue/blk wire in the ALDL connector that I snipped out of the donor harness under the dash, couldn't see where that went. Guessing I can lose that. (YES)
And in this shot you can see the red mystery wire that comes in with the ECM connectors. One side goes to the power strip/block with a fuseable link.
In GM wiring practice solid red indicates direct connection to battery (10-12 AWG), solid orange indicates fused battery line and pink with various color stripes indicates fused ignition line.
Since you are putting into older vehicle I would install an auxiliary relay panel (see Painless Part# 70107 Fuse Block / 7 Circuits kit
http://www.painlessperformance.com/M...nstruction.pdf).
This panel would off load current that otherwise would have to travel through 50 year old ignition switch!
More to come... Just hang on tight.
//RF