U1162 Loss of Rear Door Module Serial Data

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

SCHEMATIC
Refer to Door Control Module Schematics Rear Door Module and Door Lock/Indicator Schematics Left Front Power Door Components schematics.

CIRCUIT DESCRIPTION
The simple bus provides a means for information exchange among the vehicle door modules. Door module information on inputs and commanded outputs are converted to serial bus interface data for exchange among the door modules. The DDM can also take information from modules connected to the class 2 serial data circuit and relay the command to the simple bus interface. The vehicle power mode message (ignition switch position) from the DIM is an example. The DDM periodically addresses each module on the simple bus interface. When a module does not respond to the DDM, the DTC for that module is set.

CONDITIONS FOR RUNNING THE DTC
^ Diagnostic trouble codes B1982 and B1983 do not have a current status.
^ The driver door module has power.
^ The driver door module has received an input or a class 2 "wake-up" message.

CONDITIONS FOR SETTING THE DTC
A response message from the rear door module is not received by the DDM after 2 requests.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC will clear when a response message from the failed door module is detected or at the end of the current ignition cycle.
^ A history DTC will clear upon receipt of a scan tool Clear DTCs command.

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
1. Diagnostic trouble codes U1161, U1162 and U1170 set simultaneously indicate a total malfunction of the simple bus serial data circuit.
2. When DTCs U1161 and U1162 set simultaneously but U1170 does not set, the malfunction is likely to be caused by an open in the simple bus serial data circuit between the DDM and the rear fuse block.
3. The open in the simple bus serial data circuit is between the DDM and the rear fuse block.
5. Loss of communications with individual modules on the simple bus serial data circuit is due to an unpowered module, an open in the simple bus serial data circuit, or a module malfunction.
9. The simple bus serial data circuit is shorted to voltage or ground. The condition may be due to the wiring or due to a malfunction in one of the modules. When testing the wiring for a short, make sure there is not a module connected to the wire being tested.
11. Operating the window and locks from the scan tool via the class 2 serial data circuit isolates the cause of the malfunction to the simple bus serial data circuit.
12. The DDM has the capability of controlling the driver door functions. The malfunction must be due to the DDSA.
13. The following steps isolate the door module which is preventing simple bus communications.