Ignition Interlock

Can a weakened battery cause the ignition interlock switch to malfunction? Just lately the car won’t crank unless I jiggle the shift lever a couple of times, then turn the key to start a couple of times. 2004 Pontiac Grand Am.

More likely a worn or mis-adjusted interlock switch than a weak battery. However, if you know the battery is weak why not get a new battery?

weak battery? have you cleaned the posts and lugs and checked the ground strap to body connection for rust? Is your charging system giving full charge to your battery? Is the fluid level in your battery up to the mark? How old is the vehicle and do you have a lot of keys on the key fob?

It sounds more like there’s a problem with the park/neutral safety switch. The next time you go to start the engine, turn the igntion switch to the run position so the dash lights come on, step on the brake pedal and shift the transmission into neutral, and then try starting the engine. If the engine starts the park/neutral safety switch is defective.