Circuit Description
When the ignition switch is first turned to RUN, the SIR Fuse applies battery voltage to the inflatable restraint sensing and diagnostic module (SDM) at the ignition positive voltage input, terminal 3. The battery voltage is applied to the instrument cluster. The instrument cluster responds by flashing the AIR BAG warning lamp 7 times. The SDM performs tests on the SIR system while the instrument cluster is flashing the warning lamp. If the SDM detects no malfunctions, the SDM commands the instrument in order to turn the warning lamp OFF. If the SDM detects a malfunction, the SDM commands the instrument cluster in order to turn the warning lamp ON. The SDM commands the instrument cluster over the serial data line Class 2.
Diagnostic Aids
If the instrument cluster receives no message from the SDM the instrument cluster will perform the following steps when the ignition is turned to RUN:
| • | Flash the AIR BAG warning lamp 7 times. |
| • | Turn the warning lamp ON. |
| • | Set the DTC U1255 (General Loss of Class 2 Serial Data). |
| • | The instrument cluster will set DTC U1088 if the following occur: |
| - | The ignition is in the RUN position. |
| - | The instrument cluster loses communication with the SDM. |
When measurements are requested in this table, use the J 39200 DMM with the correct terminal adapter from the J 35616 Connector Test Adapter Kit. When an inspection for proper connection is requested, refer to Testing for Electrical Intermittents in Wiring Systems. When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit and refer to Wiring Repairs in Wiring Systems.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
DEFINITION: AIR BAG Warning Indicator flashes seven times, stays on, with no DTCs set. | ||||
1 | Was the SIR Diagnostic System Check performed? | -- | ||
2 |
Will scan tool command the AIR BAG Warning Indicator ON then OFF? | -- | ||
3 | Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Have the repairs been completed? | -- | -- | |
4 | Suspect the instrument panel cluster (IPC). Refer to Instrument Cluster System Check in Instrument Panel, Gauges, and Console. Have the repairs been completed? | -- | -- | |
