My brother has a 2000 Chevrolet Astro van. He has been chasing some ignition system problems. He has replaced the cap, rotor, and the plugs and wires on the driver's side. I don't know why he did not do the plugs and wires on the passenger side. Yesterday the van ran fine, after he found the coil wire was loose. Today though the van will not start. He plugged a spark plug into the coil wire and he gets a spark. He does not get spark after the cap. Any ideas? Thanks.