I have a 1998 WS6 Pontiac Trans Am. it's all of a sudden throwing a 343 code, I have changed cam timing sensor, let me clarify this I have changed every sensor on the motor check continuity on all the wires and still throwing a 343 code high voltage. I now have changed the ECM and still doing the same thing 343 code I'm lost. Thanks Jim

 

what voltage does your alt put out at idle? can you observe logged PCM voltage? are those two things close to matching?

 

I will check those two things thanks.