Wiring for the bench... Wiring for the bench...
I mounted the harness to an old board so I could move the thing easily. Making the proper connections was the next issue.
My harness is from a 1988 88 Olds ('783), so I know I've got differences from a real 1227747 truck harness. Known differences are marked by "*". Refer to the manual for YOUR harness. This table is primarily for my purposes.
| Pin | Wire Color | Destination | Optional |
| A1 | drk grn/wht | Fuel pump relay | |
| A2 | grn/blk* | Air Port | yes |
| A3 | grn/yel | Canister Purge | yes |
| A4 | gray | EGR | yes |
| A5 | brn/wht | SES Light | |
| A6 | pnk/blk | Ign power | |
| A7 | tan/blk | MT/Shift, or TCC | yes |
| A8 | orgn | Serial Data | |
| A9 | wht/blk | Diagnostic Test | |
| A10 | brn (becomes brn/white INSIDE THE CAR) | VSS | |
| A11 | black* | MAP Grnd | |
| A12 | blk/wht | ECM Grnd | |
| B1 | orgn | Battery | |
| B2 | tan/wht (was open for '7783) | Fuel pump input | |
| B3 | blk/red | Dist ref low | |
| B4 | Wht* | not used on '7747 | yes |
| B5 | ppl/wht | Distr ref pulse | |
| B6 | (was yellow) | not used on '7747 | yes |
| B7 | yellow/blk* | EST Retard (module on firewall) | |
| B8 | grn | A/C Signal | yes |
| B9 | (blank) | not used on '7747 | yes |
| B10 | org/blk | P/N Switch | |
| C1 | (blank) | not used on '7747 | yes |
| C2 | (blank) | not used on '7747 | yes |
| C3 | grn/blk | IAC | |
| C4 | grn/wht | IAC | |
| C5 | blu/wht | IAC | |
| C6 | blu/blk | IAC | |
| C7 | drk grn* | not used on '7747 | yes |
| C8 | lght blu* | 4th gear switch | yes |
| C9 | lt yel* | Crank (?) to interior | yes? |
| C10 | yel | Coolant temp | |
| C11 | beige* | Map | |
| C12 | blk/yel | Injector (not used on the '7747) | yes |
| C13 | Drk Blu | TPS | |
| C14 | gry | 5v ref (sensors) | |
| C15 | blk/grn | Injector (not used in '747) | yes |
| C16 | orng | battery | |
| D1 | blk/wht | ground | |
| D2 | grn* | ground? | |
| D3 | not used on '7747 | yes | |
| D4 | wht* (moved by me) | Spark timing out | |
| D5 | tan/blk | Ign module bypass | |
| D6 | tan | O2 ref low (ie gnd) | |
| D7 | ppl | O2 sensor high | |
| D8 | ppl/wht | ?? | yes |
| D9 | blk/wht | ?? | yes |
| D10 | lt ppl | ?? | yes |
| D11 | blk/pnk | AC Relay and a sensor--not used on '7747 | yes |
| D12 | blk | Injector (not used on '7747) | yes |
| D14 | blk/gry | Injector | |
| D15 | blk/ppl | Injector | |
| D16 | blk/red | Injector | yes |
As it turns out, the '7747 uses only 2 injector drivers and a couple of the pins are tied together internally. Those pins are C15+D14 and D15+D16.
BTW-- the '7783 used the following
| Pin | Injector for Cyl |
| C12 | 5 |
| C15 | 2 |
| D12 | 6 |
| D14 | 1 |
| D15 | 3 |
| D16 | 4 |