B1155

Circuit Description
When the ignition switch is first turned to RUN, the Instrument Panel Cluster (IPC) sends 2 messages over the serial data line class 2 containing identification information. The first message contains serial data keying information. The second message contains a partial Vehicle Identification Number (VIN). The Inflatable Restraint Sensing and Diagnostic Module (SDM) receives these messages and compares them to information stored in memory. For more detailed information about the data lines, refer to Data Link Connector.

Conditions for Setting the DTC
If either or both of the messages do not match information stored in the SDM, DTC B1155 will set, along with DTC B1159 and/or DTC B1160 depending on the message that does not match. It the SDM does not receive the serial data keying message from the IPC, DTC B1159 will set without DTC B1155. If the SDM does not receive a partial VIN message from the IPC, DTC B1160 will set without DTC B1155. The POWER-ON test checks for these DTCs. The IPC sends these messages only at POWER-ON.

Action Taken When the DTC Sets
The SDM commands the IPC to turn ON the AIR BAG warning lamp and sets one or more diagnostic trouble codes.

Conditions for Clearing DTC B1155
The DTC will clear when one of the following conditions is met:
^ Current DTC
The ignition switch is turned OFF.
^ History DTC
- You issue a scan tool CLEAR CODES command.
- 250 malfunction free ignition cycles occur.

Conditions for Clearing DTC B1159 and B1160
^ Current DTC
The SDM receives the correct message over the serial data line class 2. The IPC send this message only at IPC POWER-ON.
^ History DTC:
- You issue a scan tool CLEAR CODES command.
- Once 250 malfunction free ignition cycles have occurred.

Diagnostic Aids
DTC B1155 sets only when the wrong message is sent by the IPC. State Of Health (SOH) DTCs may set in addition to DTC B1155, DTC B1159 and DTC B1160. SOH DTCs will likely clear when the malfunction causing DTC B1155, DTC B1159 and DTC B1160 to set is repaired. Refer to Diagnostic Aids for that specific SOH DTC.

Test Description
The numbers below refer to the step numbers on the diagnostic table:
2. If DTC B1155 is set, the SDM is receiving the messages from the IPC, however one of the messages is incorrect according to the SDM in the vehicle.
7. If DTC B1155 and B1159 are set, then the SDM is receiving the wrong serial data keying message from the IPC.
9. If DTC B1160 and B1159 are set without DTC B1155, then the SDM did not receive either message from the IPC.