When the ignition switch is turned to ON, the sensing and diagnostic module(SDM) will perform turn-on test to diagnose critical malfunctions within SDM itself.

The inflatable restraint sensing and diagnostic module (SDM) stores the vehicles restraint ID from the vehicle identification number (VIN) and the last 4 digits of the SDMs part number. When the ignition is turned ON, the SDM compares this information to the information stored in the body control module (BCM) over the GMLAN communication circuit. If there is a mismatch between the information stored in the SDM and BCM, DTC B1001 will set and the SDM will disables all deployments.

This DTC is an indication that an incorrect SDM is installed in the vehicle, or that the SDM and/or the BCM was replaced without reprogramming the BCM with the new information.

The inflatable restraint sensing and diagnostic module (SDM) runs continuous diagnostic tests on the system. When the ignition is turned ON, the SDM will check to see if the correct components are installed for the vehicle configuration. If the SDM detects that there are too few or too many components on the system, DTC B1019 will set and the SDM disables all deployments. If the SDM has been replaced, make sure that the correct part number was installed for this vehicle.

This DTC is an indication that an incorrect SDM is installed in the vehicle.

The inflatable restraint sensing and diagnostic module (SDM) monitors the ignition 1 signal from the ignition switch. When the vehicle ignition switch is placed in the RUN or CRANK position the switch supplies voltage to the SDM ignition 1 input terminal. If an open, short to voltage, or short to ground in this SDM ignition 1 circuit is detected then DTC B1370 will set.

A history DTC maybe caused by an intermittent short or open in the ignition 1 circuit.

The GMLAN serial data circuits are controller area network (CAN) High and/or Low speed serial data buses used to communicate information between the control modules. Typical data transmission speeds must be high enough to ensure that a required real-time response is maintained.

The SDM continuosly checks the cut-off switch position and circuit defect by letting the rehular voltge flow through the cut-off switch circuit and verify the current.

The module setting the DTC has attempted to establish communications on the GMLAN circuits for more than 7 times.

Modules connected to the GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have programmed information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are also supervised and some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 milliseconds. Each message contains the identification number of the transmitter module. When a message that indicates the availability of the transmitter module is not received, the receiver module sets a DTC U01xx where xx is equal to the 2-digit identification number of the transmitter module.

A module with a GMLAN serial data circuit malfunction or which loses power during the current ignition cycle will have a Lost of Communication DTC set by other modules that depend on information from that failed module. The modules that can communicate will set a DTC indicating the module that cannot communicate.

Modules connected to the GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have programmed information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are also supervised and some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 milliseconds. Each message contains the identification number of the transmitter module. When a message that indicates the availability of the transmitter module is not received, the receiver module sets a DTC U01xx where xx is equal to the 2-digit identification number of the transmitter module.

A module with a GMLAN serial data circuit malfunction or which loses power during the current ignition cycle will have a Lost of Communication DTC set by other modules that depend on information from that failed module. The modules that can communicate will set a DTC indicating the module that cannot communicate.