No, the ignition switch wires cannot be used to monitor if the engine is running.
The few items that you can use are :
1. Charge indicator circuit. If alternator fails, this would not work.
2. Oil pressure circuit If pressure switch is faulty, it would not work.
3. Engine rpm which for diesels needs special adapters if vehicle is not equipped. This would be the best system to use.
4. Engine vacumn. You can attach a vacumn switch that works when engine is running and this can be used to connect whatever warning indicators.
Monday, January 19th, 2009 AT 6:30 AM