Diagnostic circuit for vehicle device control module

The present invention relates to vehicle control modules, and more particularly to a vehicle control module that controls deployment of squib-activated vehicle devices. A control module for a vehicle device control system contains a diagnostic circuit with one or more ASICs having a plurality of loops. The loops may contain either a squib, forming a squib loop, or a replacement resistor, forming a replacement resistor loop. A multiplexer connected to one loop of the ASIC diagnoses all of the replacement resistor loops. By using a multiplexer to detect replacement resistors, the invention eliminates the need to include an additional ASIC just to diagnose the replacement resistor loops.