Chart E - SDM Cannot Communicate Through Serial Data Circuit

Wiring Diagram:

CIRCUIT DESCRIPTION:
- When the SDM recognizes "Ignition 1" voltage, applied to terminal "B9", is greater than a specified value, the "AIR BAG" warning lamp is flashed seven times to verify operation and serial data communication is enabled. At this time the SDM performs "Turn-ON" tests followed by "Current Source Diagnostics" and "Continuous Monitoring" tests. When a malfunction is detected the SDM sets a current diagnostic trouble code and illuminates the "AIR BAG" warning lamp. The SDM will clear current diagnostic trouble codes and move them to a history file when the malfunction is no longer detected and/or the ignition switch is cycled, except for DTCs 51, 52 and 71. DTC 51 can only be cleared using a scan tool "Clear Codes" command. DTCs 52 and 71 may not clear after a "Clear Codes" command is issued.

Diagnostic Chart - Part 1:

Part 2:

TEST DESCRIPTION: Number(s) below refer to circled number(s) on the diagnostic chart.
1. An improper connection to the data link connector will prevent communications from being established.
2. This test checks for an open in the "Serial Data" circuit.
3. This test checks whether an abnormality is in SDM or in any other part. Once the integrity of the "Serial Data" circuit including proper connections has been confirmed and ECM can communicate, the SDM must be malfunctioning.
4. This test check for a short to ground in the "Serial Data" circuit.
5. This test checks for a short to B+ or other power circuit in the "Serial Data" circuit.
6. This test checks whether the malfunction is caused by a short in ECM or in ABS control module (if equipped). With ECM and ABS control module disconnected from "Serial Data" circuit, if SDM and the scan tool can communicate, ECM or ABS control module may be malfunctioning. Once the integrity of the "Serial Data" circuit including proper connections has been confirmed and SDM cannot communicate, the SDM must be malfunctioning.