GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 Seville 🢒 DTC 🢒 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 is converted to serial data and sent out on the power door serial data line for exchange among the door modules. The Driver Door Module (DDM) also communicates with the other vehicle modules via the Class 2 Serial Data circuit and can take the class 2 serial data information and relay it, via the power door serial data Iine, to the other door modules. The vehicle power mode message (ignition switch position) from the DIM is an example of class 2 communications between the DDM and the other vehicle modules. 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

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.

Diagnostic Aids
    • Loss of communications with individual door modules may be due to a malfunction of the power door serial data circuit, however, lost communications could also be due to an unpowered or ungrounded module. This includes the driver door switch assembly (DDSA), which is also a door module.
        In addition, the driver door module (DDM) or front passenger door module (PDM) will fail to communicate if the battery positive voltage circuit between the door module and corresponding power window sensor is shorted to ground, a condition which would open the associated door module fuse in the rear fuse block. Therefore, when directed to test the battery positive voltage circuit of the door module C1 connector, both battery positive voltage circuits of the connector must be tested for opens and shorts to ground, when it is a front door module that has lost communications.
    • The rear door modules each have a separate battery positive voltage circuit, associated with door module connectors C1, however, the circuits are both fed by the same 10 amp RRDRMDL fuse located in the rear fuse block. A short to ground in either one of these rear door module battery positive voltage circuits, may open the fuse and cause DTCs U1162 and U1163 to be simultaneously set current.

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. This step determines if the open in the power door serial data circuit is between the DDM and splice S302.

    4.

  4. This step determines if the battery positive voltage circuit between the driver door switch assembly (DDSA) and the DDM, or, between the affected door module and the fuse block, is open or shorted to ground.

    5.

  5. This step determines if the battery positive voltage circuit between a front door module and the associated power window sensor is open or shorted to ground. A short to ground in this circuit would cause the corresponding front door module fuse in the rear fuse block to open and set the door module communications DTC.

    6.

  6. This step determines if 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. 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.

    8.

  8. This step determines if the driver door switch assembly (DDSA) is the cause of the malfunction. The DDSA processes driver door window and lock switch signals to the DDM and, 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 and Power Window Schematics

1

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

Go to Step 9

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 either 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 22

Go to Step 16

5

Important: If the DTC set by itself is U1170, 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 circuits associated with connector C1 of the door modules that are 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 22

Go to Step 6

6

If the door module not communicating is the front passenger door module, test the battery positive voltage circuit between the module and the associated power window sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 7

7

Important: If the DTC set by itself is U1170, 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 circuits associated with connector C1 of the door 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 22

Go to Step 8

8

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 22

Go to Step 17

9

  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 voltage. Turn ON the ignition, with the engine OFF when you test for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 10

10
  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 voltage. Turn ON the ignition, with the engine OFF when you test for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 11

11

  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 12

Go to Step 16

12

  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 13

Go to Step 18

13

    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 14

Go to Step 17

14

    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 15

Go to Step 17

15

    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 16

Go to Step 17

16

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 22

Go to Step 19

17

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 22

Go to Step 20

18

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 22

Go to Step 21

19

Replace the DDM. Refer to Door Control Module Replacement .

Did you complete the replacement?

Go to Step 22

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20

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

Did you complete the replacement?

Go to Step 22

--

21

Replace the DDSA. Refer to Front Door Switch Replacement .

Did you complete the replacement?

Go to Step 22

--

22

Use the scan tool in order to clear the DDM DTCs.

Did you complete the action?

Go to Diagnostic System Check - Door Systems

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