EFI / Painless - Engine light constant

[Ourobos]

I have a friend with 74, EFI conversion with all painless wiring, A9L computer. No matter what, the engine light is on and he can't pull codes. Truck runs good for a while then will start running bad and missing. Anyone real familiar with the painless EFI swap and have any quick ideas to check. I haven't laid eyes on it, but I'm leaning on a short, improperly wired wire, or bad circuit or capacitor in ECU.

 

[904Bronco]

The ECU supplies a ground to the circuit to make the light come on... Check wiring...

But if you cannot pull codes... or go into test mode, Then I am thinking bad ECU based on what you said.