This paper discusses the use of hierarchies of function in reasoning about automotive electrical systems. Such hierarchies enable more powerful reasoning for applications such as diagnosis, failure mode and effects analysis, sneak circuit analysis and design verification, while also structuring the domain and thus reducing the complexity at any one level. The context of this discussion is the existing AutoSteve system for performing these tasks. The AutoSteve system works with single level electrical schematics, one schematic for each subsystem in the car, and with a set of functional labels for each subsystem. The functional labels can be used to interpret what is happening in a qualitative simulation of the circuit.