* Faulty ignition switch: This is a common culprit.
* Problem with the wiring harness: A short, broken wire, or corroded connection in the ignition system wiring.
* Passlock system malfunction: This is the anti-theft system. A failed Passlock module or a problem with the transponder key could cause this code.
* Issues with the vehicle speed sensor (VSS): While less common for a Code 15, a malfunctioning VSS can sometimes contribute to this code, especially if related to the theft-deterrent system's circuits.
You'll need to troubleshoot further to pinpoint the exact cause. A mechanic with a diagnostic scanner can be very helpful in this process, as it's difficult to reliably diagnose without the proper tools. Simply checking fuses and visually inspecting wiring is a good starting point, but a professional diagnosis is often required to fully resolve a code 15 issue.
