no crank no start, suspected bad ecm


New member
bought an 08 G5 (2.2L auto) for $200 with electrical issues. when i first got into it, it would not start when key was turned. by manipulating the engine wiring harness or the one that goes from firewall to fuse box, i was able to get it started only after i heard the TAC priming. every time i would hit a bump or move too much in the car, it would shut off and would need to manipulate wires to get it to start again. previous owner stated that it was a intermittent problem and that’s why they parked it. they said they replaced fuse box, and I even took it apart to clean, found one broken connection to positive cable but soldered back together for good connection. cleaned and inspected all grounds inside the vehicle, none loose or corroded but cleaned and installed them tight anyways. G103 and G105 were okay, corroded but after cleaning and reinstalling i still had the same problem. car will not start, has good communication to ECM keeps throwing code P1682 (common from what i’ve read) driver 5 line 2. 6V power at ignition switch when plugged in and on crank position so i know that’s good. i’m not sure how the ignition system works in these cars but i suspect either the ecm is bad (intermittently starting and stalling) but when it was finally running after manipulating wires before, it would run just fine. no misfires or anything. half of interior things work. the HVAC doesn’t move blend door actuator when selector is moved, and it taps loudly when key is in ignition. A/C button doesn’t seem to work, no key in ignition alarm, no turn signal clicks, and no sound from both front speakers. airbag light is on and “POWER STEERING” is displayed on message center along with “SVC AIRBAG”. steering wheel controls work, but cannot cycle through things past the odometer and oil life reset. fuel pump doesn’t run when key is in run position, the engine cranks and fuel pump runs when the relays are jumped from 30 and 87. but does not start for some reason. theft light comes on but doesn’t blink and doesn’t stay on, goes off after a few seconds as it should. i’m very confused, any help would be appreciated to point me in the right direction. thank you