U1161

DTC U1161 Loss of PASS Door Module SBI:

DTC U1161 Loss of PASS Door Module SBI (Part 1 of 2):

DTC U1161 Loss of PASS Door Module SBI (Part 2 of 2):

CIRCUIT DESCRIPTION
The SBI data line is used to communicate information between the door modules. Each module connected to the SBI is assigned its own recognition code (address). This code is used to identify which modules are communicating. Modules communicate with each other by periodically sending State of Health (SOH) messages. When the ignition switch is in RUN, each module communicating on the SBI sends a State of Health (SOH) message every 2 seconds to ensure that the system is operating properly. When the RFDM stops communicating on the SBI, for example if the RFDM loses power or ground, the SOH message it normally sends on the SBI every 2 seconds disappears. The LFDM which expects to receive that SOH message, detects its absence and sets DTC U1161 current.

CONDITIONS FOR SETTING THE DTC
^ The LFDM does not receive a State of Health (SOH) message back from the RFDM.
^ This DTC only sets if DTC B1982, B1983, U1300 or U1301 is not current in module memory.

ACTION TAKEN WHEN THE DTC SETS
^ DTC U1161 is stored in module memory.
^ The LFDM uses the default values for the initialization data.
^ This DTC does not cause a driver warning message to appear.

CONDITIONS FOR CLEARING THE DTC
^ This DTC clears (status changes from current to history) under any of the following conditions:
- The LFDM detects a State of Health Message from the LFDM.
- On each ignition cycle.
^ A history DTC clears after 50 consecutive ignition cycles if the conditions for seeing the DTC are no longer present.
^ Current and history DTCs may be cleared using a scan tool or using the On-Board System Diagnostic feature.

DIAGNOSTIC AIDS
^ .DTC module U1161 does not normally represent a failure within the module.
^ If the DTC is a history DTC, the problem may be intermittent.
^ A grounded CKT 2076 will set following DTCs U1161, U1162, U1163, and U1170.
^ An open or a high resistance wire between the LFDM and S303 will set DTCs U1161, U1162, U1163.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:
2. This step inspects for other related DTC that are set.
7. This step inspects for related DTCs that are set.
9. This step inspects the PASS MDL fuse.
11. This steps tests for baffler voltage in CKT 740 at the RFDM.
13. This steps tests for ground in CKT 451 at the RFDM.
15. This steps tests for continuity of the simple bus interface from the RFDM to the LFDM in CKT 2076.