Kingsnake2005

Hello,
I have an 86 Camaro that originally had the computerized Quadrajet. Since then, i have upgraded to an 89 TPI setup with a new custom PROM from tbichips.com. Ever since the swap the SES light will illuminate when there is no problem and go out when there is a problem. E.g. the SES light will be on and if i unplug the wire to set base timing the light goes out, or if i unplug the MAF the light goes out. The light work fine for flashing codes and goes through the normal on off on cycle with key on. If i put the ECM in diagnostic mode- I can watch the engine enter closed loop and monitor rich and lean conditions no problem. But, in normal mode, the light is on- car running fine in closed loop. I was thinking about putting in a relay on the SES wire from the ECM to invert the light when the car is running- so when the ECM provides the ground, the relay would cut the light off, and when the ECM opens the circuit, the relay could turn the light on. I thought i could also wire in a bypass toggle switch and put it on the passenger bolster so i can bypass the relay to read codes etc. What do you guys think?

Apeiron

Code 12 is no reference pulses from the distributor.

Kingsnake2005

Huh, i thought 12 was the "no problem" code. I converted the harness to a large cap HEI dizzy. could this be my problem? Which wire should i be looking at? I soldered the splices.

deadbird

Could be, IIRC, '85 was the only year for the coil in cap distributors for FI (7pin ignition control module).
Code 12 (normal) flashes because while you are running codes, the engine isn't running so, as Aperion stated, no pulses from the distributor, code 12.

Kingsnake2005

Ah, ok. So if the ecm doesn't see the refrence pulses it sets a code 12. So how do you explain the light being off when it should be on? and on when it should be off?