I turn the key and all I hear is loud repetitive clicking. The headlights are slow to come up and the dash lights are dim. Time for a new battery, or could it be another problem? Thanks.

 

Battery or poor connection to it.

 

What can bad ground wires cause?

 

If you are referring to the ground wire off the battery, it is no less important. Both cables must be well connected to form a complete circuit. Any other grounds must be in good shape if your car is going to operate like it should.

 

Battery! Just had the same problem. It would read full voltage under no strain, but under load, it would just shut off all electronics in my car. If i opened the door, there was a clicking noise from what sounded to be under the passenger side dash, and the alarm light on the dash would be blinking very fast. I thought it was a bad relay or ground, so i made the mistake of taking it to the dealership. They wanted 113 bucks for a delco battery so i told them to shove it and got an optima red top for 110. Sounds like a much better deal to me.