Circuit Description
The dual stage inflatable restraint steering wheel module deployment loop consists of the dual stage inflatable restraint steering wheel module, the inflatable restraint steering wheel module coil, and the steering wheel module high and low circuits for both stages 1 and 2. Two shorting bars used within the steering wheel module coil connector short together both the steering wheel module stage 1 high and low circuits, and the steering wheel module stage 2 high and low circuits when the connector is disconnected. This helps to prevent unwanted deployment of the inflator module during servicing. During a frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) allows current to flow through the deployment loop in order to deploy the steering wheel module. When the ignition is turned ON, the SDM performs continuous diagnostic tests on the deployment loops to check for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a diagnostic trouble code (DTC) will be stored in memory.