B0077

Schematic:

CIRCUIT DESCRIPTION
When you first turn the ignition switch to the RUN position, the inflatable restraint Sensing and Diagnostic Module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM provides input power to the Side Impact Sensor (SIS). When input power is first detected, the SIS responds by performing internal diagnostics. The SIS then sends an ID message to the SDM. The SDM will consider this to be a valid ID if the response time is less than 5 seconds after the SIS is powered up.The SIS will continually communicate a status message to the SDM. The SDM is capable of resetting the SIS by removing and applying power to it.

CONDITIONS FOR RUNNING THE DTC
^ Ignition 1 voltage is within the normal operating voltage range.
^ LF SIS loop is not shorted to voltage.
^ LF SIS loop is not shorted to ground.

CONDITIONS FOR SETTING THE DTC
^ A valid ID message is not received within 5 seconds of the LF SIS being powered up.
^ Status message is not received.
^ The SDM has failed twice to reset the LF SIS.

ACTION TAKEN WHEN THE DTC SETS
^ The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.
^ The SDM attempts to reset the LF SIS.

CONDITIONS FOR CLEARING THE DTC
^ The SDM has detected correct operation.
^ The SDM receives an OK message from the LF SIS.
^ You issue a scan tool CLEAR CODES command.
^ A history DTC will clear once 255 malfunction free ignition cycles have occurred.

When the SDM detects that no DTCs are present, the SDM commands the AIR BAG warning lamp OFF.

DIAGNOSTIC AIDS
The following can cause an intermittent condition:
^ A short between the LF inflatable restraint side impact sensor (SIS) driver senor high and driver sensor low circuits.
^ High or low resistance in the LF inflatable restraint side impact sensor (SIS) driver sensor high and driver sensor low circuits.
^ Inspect the LF inflatable restraint side impact sensor (SIS) driver sensor high and driver sensor low circuits carefully for cutting and/or chafing.
^ Refer to Testing for Intermittent and Poor Connections in Diagrams

TEST DESCRIPTION

Test Step 1 - Step 5:

Test Step 6 - Step 16:

Test Step 17 - Step 24:

The numbers below refer to the step numbers on the diagnostic table:
2. This step inspects the inflatable restraint side impact sensor (SIS) wiring harness connector.
4. This step inspects the inflatable restraint side impact sensor (SIS) connector terminals.
5. This step inspects the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector.
8. Tests for an open or high resistance in the inflatable restraint side impact sensor (SIS) driver sensor low circuit.
10. Tests for an open or high resistance in the inflatable restraint side impact sensor (SIS) driver sensor high circuit.
12. Tests for a short between the inflatable restraint side impact sensor (SIS) driver sensor high and driver sensor low circuits.
14. Tests for a short to ground in the inflatable restraint side impact sensor (SIS) driver sensor high circuit.
16. Tests for a short to ground in the inflatable restraint side impact sensor (SIS) driver sensor low circuit.
18. Tests for a short to voltage in the inflatable restraint side impact sensor (SIS) driver sensor high circuit.
20. Tests for a short to voltage in the inflatable restraint side impact sensor (SIS) driver sensor low circuit.