U1170

DTC U1170

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

CONDITIONS FOR RUNNING THE DTC
- Diagnostic trouble codes B1327, B1328, U1300, and U1301 do not have a current status.
- The driver door module has power.
- The driver door module has received an input, a power door serial data message or a class 2 wake-up message.

CONDITIONS FOR SETTING THE DTC
When a door module or the DDSA does not respond to the DDM within 2 seconds of the DDM request for a response, the DDM sets the appropriate DTC.

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 or after 50 OFF/ON ignition switch cycles without a repeat of a communications failure.

TEST DESCRIPTION

Steps 1 - 8:

Steps 9 - 13:

Steps 14 - 21:

The numbers below refer to the step numbers on the diagnostic table.
1. This step determines if there is a total malfunction of the power door serial data circuit, a condition which would set diagnostic trouble codes U1161, U1162, U1163, and U1170 simultaneously.
2. When DTCs U1161, U1162, and U1163 set simultaneously but U1170 does not set, the malfunction is likely to be caused by an open in the power door serial data circuit between the DDM and splice S302
3. Loss of communications with individual door modules may be due to an unpowered door module, a condition which would set, either DTC U1161, U1162, U1163, or U1170 individually.The driver door module (DDM) is powered by the DRVMDL 10 amp fuse and the front passenger door (PDM) is powered by the PASS MDL 10 amp fuse. The DDM, in addition, supplies power from the DRVMDL fuse to the driver door switch assembly (DDSA) via a separate battery positive voltage circuit. The rear door modules each have a separate battery positive voltage circuit, however, both circuits are powered by the RRDRMDL 10 amp fuse. If either one of the rear door modules battery positive voltage circuits is shorted to ground, the RRDRMDL fuse will open and cause DTCs U1162 and U1163 to be set simultaneously current.
6. Loss of communications with individual door modules may be due to an ungrounded door module. This step determines if the door module that is not communicating has lost ground. The ground circuit for the driver door switch assembly (DDSA) is supplied by the driver door module.
8. This step begins to determine where the power door serial data circuit short to voltage or ground is located. The shorted 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.
10. By operating the window and locks from the scan tool via the class 2 serial data circuit, this step proves that the DDM is capable of controlling the driver door functions and isolates the cause of the malfunction to the power door serial data circuit.
11. By operating the driver door window and lock from the driver door switch assembly (DDSA), this step determines if the DDSA is the cause of the malfunction.
12. This step, and the following steps, isolate the door module which is preventing power door serial data communications.