GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2003 🢒 LeSabre 🢒 Body and Accessories 🢒 Data Link Communications 🢒 DTC U1161-U1163 or U1170

Circuit Description

The power door serial data circuit provides a means for information exchange among 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. The Drivers 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 module on the power door serial data circuit. When a 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

A response from a door module on the power door serial data circuit is not received by the DDM within 2 seconds of the DDM request for a response from a door module or the driver door switch assembly (DDSA).

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

The numbers below refer to the step numbers on the diagnostic table.

  1. Diagnostic trouble codes U1161, U1162, U1163, and U1170 set simultaneously indicate a total malfunction of the power door serial data circuit.

    2.

  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.

  3. The open in the power door serial data circuit is between the DDM and splice S302.

    4.

  4. Loss of communications with individual modules may be due to an unpowered module. This includes the driver door switch assembly (DDSA), which is also a module.

    The rear door modules each have a separate battery positive voltage circuit (connectors C1), but they are both fed by the same 10 amp RRDRMDL fuse in the rear fuse block. A short to ground in either one of the rear door module battery positive voltage circuits (connectors C1) may open the fuse and cause DTCs U1162 and U1163 to be set simultaneously.

    5.

  5. Loss of communications with individual modules may be due to an ungrounded module. This includes the driver door switch assembly (DDSA), which is also a module.

    6.

  6. The power door 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.

    7.

  7. Operating the window and locks from the scan tool via the class 2 serial data circuit 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.

    8.

  8. The driver door switch assembly (DDSA) processes driver door window and lock switch signals to the DDM. Since the DDM was proven capable in step 10, the malfunction must be due to the DDSA.

    9.

  9. The following steps isolate the door module which is preventing power door serial data communications.

Step

Action

Yes

No

Schematic Reference: Door Control Module Schematics

Important: Where it is not otherwise specified in the step, the following procedure should be conducted with the ignition turned OFF to prevent an erroneous setting of DTC B0490.

1

Did you record DTCs U1161, U1162, U1163, and U1170 all with a current status?

Go to Step 8

Go to Step 2

2

Did you record DTCs U1161, U1162, and U1163 all with a current status but not U1170?

Go to Step 4

Go to Step 3

3

Did you record DTC U1161, DTC U1162, DTC U1163 or DTC U1170 by itself, or, DTCs U1162 and U1163 together with a current status?

Go to Step 5

Go to Testing for Electrical Intermittents in Wiring Systems

4

Test the power door serial data circuit for an open between the DDM and the circuit splice.

Did you find and correct the condition?

Go to Step 21

Go to Step 15

5

Important:: If the DTC set by itself is U1170, you would test the battery positive voltage circuit between the driver door module (DDM) and the driver door switch assembly (DDSA) for an open or a short to ground.

Test the battery positive voltage circuit associated with connector C1 of the module that is not communicating for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 6

6

Important:: If the DTC set by itself is U1170, you would test the ground circuit between the driver door module (DDM) and the driver door switch assembly (DDSA) for an open.

  1. Turn OFF the ignition.
  2. Test the ground circuit associated with connector C1 of the module that is not communicating for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 7

7

Test the power door serial data circuit of the module that is not communicating for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 16

8

Important: Turn ON the ignition, with the engine OFF when you test for a short to battery positive voltage.

  1. Turn OFF the ignition.
  2. Disconnect the DDM from the DDSA.
  3. Test the power door serial data circuit between the DDM and DDSA for a short to ground or a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 9

9

Important: Turn ON the ignition, with the engine OFF when you test for a short to battery positive voltage

  1. Turn OFF the ignition.
  2. Disconnect the PDM, the LRDM and the RRDM.
  3. Test the power door serial data circuit of each module for a short to ground or a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 10

10

  1. Connect the DDM.
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. Select the Special Functions for the DDM.
  5. With the scan tool, operate the driver door power window.
  6. With the scan tool, operate the driver door power lock.

Does the window or lock operate properly?

Go to Step 11

Go to Step 15

11

  1. Turn OFF the ignition.
  2. Connect the DDSA.
  3. Turn ON the ignition, with the engine OFF.
  4. Operate the driver door power window from the driver door switch assembly (DDSA).
  5. Operate the driver door power lock from the driver door switch.

Does the window or lock operate properly?

Go to Step 12

Go to Step 17

12

    Important: Operate the power window from the switch at the passenger door before operating it from the driver door switch assembly (DDSA). The following procedure assumes the power window operates properly.

  1. Turn OFF the ignition.
  2. Connect the PDM.
  3. Turn ON the ignition, with the engine OFF.
  4. Operate the passenger door power window from the driver door switch assembly (DDSA).

Does the window operate properly?

Go to Step 13

Go to Step 16

13

    Important: Operate the power window from the switch at the left rear door before operating it from the driver door switch assembly (DDSA). The following procedure assumes the power window operates properly.

  1. Turn OFF the ignition.
  2. Connect the LRDM.
  3. Turn ON the ignition, with the engine OFF.
  4. Operate the left rear door power window from the driver door switch assembly (DDSA).

Does the window operate properly?

Go to Step 14

Go to Step 16

14

    Important: Operate the power window from the switch at the right rear door before operating it from the driver door switch assembly (DDSA). The following procedure assumes the power window operates properly.

  1. Turn OFF the ignition.
  2. Connect the RRDM.
  3. Turn ON the ignition, with the engine OFF.
  4. Operate the right rear door power window from the driver door switch assembly (DDSA).

Does the window operate properly?

Go to Step 15

Go to Step 16

15

Inspect for poor connections at the harness connector of the DDM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 18

16

Inspect for poor connections at the harness connector of the module that is not communicating. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 19

17

Inspect for poor connections at the harness connector of the DDSA. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 20

18

Replace the DDM. Refer to Door Control Module Replacement .

Did you complete the replacement?

Go to Step 21

--

19

Replace the inoperative door module. Refer to Door Control Module Replacement .

Did you complete the replacement?

Go to Step 21

--

20

Replace the DDSA. Refer to Front Door Switch Replacement .

Did you complete the replacement?

Go to Step 21

--

21
  1. Use the scan tool in order to clear the DDM DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK