CB Shops

I have a 1993 lumina with 3.1 that has a no start problem?

Grounding A/B at DLC causes engine fan to come on, test MIL status with tech 1 and it failed telling me there’s a problem in the diagnostic circuit. Problem started with a shorted battery which I tried to trickle charge when I noticed it wasn’t drawing amps and started causing door locks to lock and make various electrical chatter. Replaced batt. no power at fuel pump relay switched circuit from ecm. DTC 12 will not flash through tech 1 or jumping terminal A/B. cranks but no fire. all fuses are good. is it possible i fried the ecm when i tried to charge the battery without knowing it was shorted out? Can not pull codes with tech 1 or jumper method. I’m a class 8 tech so this tech 1 is unfamiliar to me but i can follow someone’s instructions and have been in the industry for 15 years so i understand any technical info that comes my way.

these cars have a problem with the wiring harness shorting out where it runs down behind the water pump assembly.very common electrical problem created by heat from the water pump try to look behind it and check the plastic sleeve over the wiring for burnt spots.the first time my shop figured out this problem we had already started replacing the harness

Hanford Zumba Relay for Life- Mil Horas