Control Module Power Supply: Diagnosis

WARNING: This page is about a different car, the 2007 Saab 9-5 and 2006 Saab 9-5. However, it is still accessible from the selected car via links, so may be relevant.

If no current from either the +30 or +15 circuits is present, the engine will not start and the system cannot be contacted with the diagnostic tool.

Fig 1: Control Module Power Supply Circuit Diagram
Courtesy of SAAB-SCANIA OF AMERICA, INC.

If no current is supplied to the control module from the main relay, diagnostic trouble code P1640 will be generated, the throttle will close and the engine will stop.