Scan Tool Does Not Communicate With SDM

Circuit Description

The data link connector Data Link Connector (DLC) is the provision for communicating with the Inflatable Restraint Sensing and Diagnostic Module (SDM) and other Class 2 modules that are on the same data line. The DLC supplies B+ and ground to the scan tool. The scan tool is connected to the DLC in order to perform the following functions:

^ Read the data list

^ Read diagnostic trouble codes (DTCs)

^ Clear DTCs

Diagnostic Aids

The loss of serial data communication between the SDM and the instrument cluster will cause the AIR BAG warning lamp to come ON solid. Refer to A Diagnostic System Check. Diagnostic System Check

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

2. This step checks for proper operation of the scan tool.

3. This step checks to see if the scan tool can communicate with another module on the same Class 2 data line.

4. This step checks to see if the AIR BAG Fuse is blown.

6. This step determines if there is a short to ground in circuit 1139 or if there is a malfunctioning SDM.

9. This step checks to see if there an open or a high resistance in circuit 1139.

11. This step checks to see if there is an open or a high resistance in circuit 1128.