Cadillac XLR Forum Discussion, Intermittent no start 2005 XLR in Past Cadillac Vehicle Discussion; All the others tuff seems to work normally, it just won't start with the button sometimes. It is happening more ...
Koop, it could be a lot of things, but first you have to isolate it to an ignition, interlock (transmission/brake), or Easy Key sub-system problem.
It could be as simple as a bad ignition switch. It could be an intermittent switch that acknowledges when the brake is depressed during the ignition sequence. There are too many troubleshooting paths to try to write up a viable solution without more symptoms presented. Intermittent faults are some of the most difficult to troubleshoot.
I've read about this problem only once and it was isolated to a faulty ignition switch. They're relatively cheap and easy to replace. You can try re-seating the connector and/or cleaning the connector contacts. Also, you can remove the switch and cycle it a bunch of times with an ohmmeter attached to see how reliably it functions.