Having a hard time starting - my LS1 was cutting off when I disconnected the battery at idle. Alternator right? I replaced it. Very careful with harness wiring, ground wire etc. After idling awhile it still wouldn't start right up - might have killed the battery after waiting so long, will have to have it checked. When idling it reads 13-14 volts. I drove it around the block and noticed the speedometer was pinged all the way to the right - not working. WTH? I didn't get near the transmission.