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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2001 🢒 Park Avenue 🢒 Engine 🢒 Engine Electrical 🢒 Scan Tool Does Not Communicate with Class 2 Device

Circuit Description

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. Connecting a scan tool to the DLC allows communication with the modules for diagnostic purposes.

Diagnostic Aids

The engine will not start when there is a total malfunction of the class 2 serial data circuit while the engine is not running.

Test Description

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

  1. A partial malfunction in the class 2 serial data circuit uses a different procedure from a total malfunction of the class 2 serial data circuit.

    2.

  2. The DTC U1300 and U1301 may be retrieved with a history status. These DTCs are not the cause of the present condition.

    3.

  3. A State of Health DTC with a history status may be present along with a U1000 or a U1255 with a current status. This indicates that the malfunction occurred when the ignition was on. Any additional DTCs beginning with "U" indicate a specific module is not communicating. The U1XXX test is used to diagnose this concern.

    4.

  4. Data link connector terminals 2 and 5 provide the connection to the class 2 serial data circuit and the signal ground circuit respectively.

    5.

  5. An open in the class 2 serial data circuit between the DLC and connector C200 will prevent the scan tool from communicating with any module. This condition will not set a DTC.

    6.

  6. The class 2 serial data circuit is shorted to voltage or to ground. This step isolates the concern to the five modules not linked through a fuse panel.

    7.

  7. This step adds the rear fuse panel

    8.

  8. This step adds the 3 modules linked through the rear fuse panel.

    9.

  9. This step adds the modules linked in the engine compartment.

    10.

  10. The modules in the 3 loops (base, interior and engine compartment) must be diagnosed in the following order:

    Base -- body control module (BCM), instrument panel integration module (IPM), instrument panel cluster (IPC) and theft deterrent control module last.

    Interior -- memory seat module (MSM), inflatable restraint sensing and diagnostic (SDM) module and remote control door lock receiver (RCDLR) last.

    Engine Compartment -- powertrain control module (PCM) first and electronic brake control module (EBCM) second. The connector C101 is diagnosed last.

    11.

  11. If there are no current DTCs that begin with a "U", the communication malfunction has been repaired.

    12.

  12. The communication malfunction may have prevented diagnosis of the customer complaint.

Step

Action

Yes

No

1

Does the scan tool power up?

Go to Step 2

Go to Scan Tool Does Not Power Up

2

  1. Turn ON the ignition with the engine OFF.
  2. Attempt to communicate with each module on the Class 2 serial data circuit. (If using a Tech 2, obtain this information using the Class 2 Message Monitor feature.)

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 3

Go to Step 7

3

  1. Select the Display DTCs function for each module. (If using a Tech 2, use the Class 2 DTC Check feature in order to determine which modules do have DTCs set.)
  2. Record all of the displayed DTCs, the DTC status and the module which set the DTC.

Did you record any DTCs in the range of U1000 to U1305?

Go to Step 4

Go to Control Module References in Body Control System for the applicable Diagnostic System Check

4

Are the DTCs U1300, U1301 or U1305 retrieved from any module?

Go to Step 5

Go to Step 6

5

Important:: Turn ON the ignition, with the engine OFF, when testing for a short to voltage. Use the DMM MIN/MAX function to capture intermittent conditions.

Test the class 2 serial data circuit for an intermittent short to ground or an intermittent short to voltage. Refer to the following in Wiring Systems:

    •  Circuit Testing
    •  Connector Repairs
    •  Wiring Repairs

Did you find and correct the condition?

Go to Step 28

Go to Step 6

6

Are U1000 or U1255 the only DTCs displayed in the previously specified range?

Go to DTC U1000 and U1255

Go to DTC U1001-U1254

7

  1. Turn OFF the ignition.
  2. Disconnect the scan tool from the data link connector (DLC).
  3. Inspect for poor connections at terminals 2 and 5 of the DLC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Control Module References in Body Control System for the applicable Diagnostic System Check

Go to Step 8

8

Test the ground circuit at terminal 5 of the DLC for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Control Module References in Body Control System for the applicable Diagnostic System Check

Go to Step 9

9

Test the class 2 serial data circuit of the DLC for an open between terminal 2 and connector C200. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Control Module References in Body Control System for the applicable Diagnostic System Check

Go to Step 10

10

  1. Disconnect the rear fuse block connector C1.
  2. Disconnect the IP fuse block connector C1.
  3. Install a scan tool.
  4. Turn ON the ignition with the engine OFF.
  5. Attempt to communicate with any module still connected to the DLC through the class 2 serial data circuit.

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 11

Go to Step 16

11

  1. Turn OFF the ignition.
  2. Disconnect rear fuse block connector C2.
  3. Reconnect the rear fuse block connector C1.
  4. Turn ON the ignition with the engine OFF.
  5. Attempt to communicate with any modules still connected to the DLC through the class 2 serial data circuit.

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 12

Go to Step 26

12
  1. Turn OFF the ignition.
  2. Disconnect the IP fuse block connector C4.
  3. Reconnect the IP fuse block connector C1.
  4. Turn ON the ignition with the engine OFF.
  5. Attempt to communicate with any modules still connected to the DLC through the class 2 serial data circuit.

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 13

Go to Step 27

13

  1. Turn OFF the ignition.
  2. Reconnect the rear fuse block connector C2.
  3. Turn ON the ignition with the engine OFF.
  4. Attempt to communicate with any modules still connected to the DLC through the class 2 serial data circuit.

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 14

Go to Step 21

14
  1. Turn OFF the ignition.
  2. Disconnect the connector C101.
  3. Reconnect the IP fuse block connector C4.
  4. Turn ON the ignition with the engine OFF.
  5. Attempt to communicate with any modules still connected to the DLC through the class 2 serial data circuit.

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 15

Go to Step 25

15

  1. Turn OFF the ignition.
  2. Reconnect the connector C101.
  3. Turn ON the ignition with the engine OFF.
  4. Attempt to communicate with any modules still connected to the DLC through the class 2 serial data circuit.

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 29

Go to Step 21

16
  1. Turn OFF the ignition.
  2. Disconnect the connector C200.
  3. Turn ON the ignition with the engine OFF.
  4. Attempt to communicate with any modules still connected to the DLC through the class 2 serial data circuit.

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 17

Go to Step 21

17
  1. Turn OFF the ignition.
  2. Disconnect the DDM.
  3. Reconnect the connector C200.
  4. Turn ON the ignition with the engine OFF.
  5. Attempt to communicate with any modules still connected to the DLC through the class 2 serial data circuit.

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 18

Go to Step 20

18
  1. Turn OFF the ignition.
  2. Test the class 2 serial data circuit between DDM and rear fuse block connector C1 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 28

Go to Step 19

19
  1. Turn OFF the ignition.
  2. Replace the DDM. Refer to Control Module References in Body Control System for the appropriate Repair Instructions for module replacement.

Did you complete the replacement?

Go to Step 28

--

20
  1. Turn OFF the ignition.
  2. Test the class 2 serial data circuit between DDM and connector C200 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 28

Go to Step 21

21

Perform the following, one module at a time starting at the module furthest from the DLC, for each module on the class 2 circuit now attached to the DLC.

  1. Turn OFF the ignition.
  2. Disconnect the furthest module from the DLC still connected to the class 2 serial data circuit.
  3. Turn ON the ignition with the engine OFF.
  4. Attempt to communicate with any modules still connected to the class 2 serial data circuit.

Does the scan tool communicate with any module on the class 2 serial data circuit?

Go to Step 22

Go to Step 25

22

Test the class 2 serial data circuit after the last module disconnected for a short to ground or a short to voltage. (Turn ON the ignition with the engine OFF when testing 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 28

Go to Step 23

23

Inspect for poor connections at the harness connector of the last module disconnected. 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 28

Go to Step 24

24

Replace the last module disconnected. Refer to Control Module References in Body Control System for the appropriate Repair Instructions for module replacement.

Did you complete the replacement?

Go to Step 28

--

25

Repair the class 2 serial data circuit(s) and in-line connector(s) between the last module disconnected in the branch being diagnosed. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

26
  1. Turn OFF the ignition.
  2. Replace the rear fuse block. Refer to Control Module References in Wiring Systems for the appropriate Repair Instructions for module replacement.

Did you complete the replacement?

Go to Step 28

--

27
  1. Turn OFF the ignition.
  2. Replace the IP fuse block. Refer to Control Module References in Body Control System for the appropriate Repair Instructions for module replacement.

Did you complete the replacement?

Go to Step 28

--

28

  1. Connect all of the disconnected modules.
  2. Connect any other disconnected connectors.
  3. Install a scan tool.
  4. Turn ON the ignition leaving the engine OFF.

    5. Important: The scan tool may require a power up reset before communication will occur due to a short on the class 2 serial data circuit. Turn off or disconnect the scan tool before you display DTCs.

  5. Wait for 10 seconds.
  6. Select the display DTCs function for each module. (If using a Tech 2, use the Class 2 DTC Check feature in order to determine which modules do have DTCs set.)
  7. Record all of the displayed DTCs and the DTC status.

Did you record any DTCs which begin with a "U" and with a current status?

Go to Step 30

Go to Step 29

29

Did you record any DTCs which do not begin with a "U"?

Go to Step 30

Go to Step 32

30

Diagnose the DTCs as directed by the diagnostic procedures for the particular module or malfunction. The PCM may have DTC(s) P1602 to P1615, or P1626 set. If only P1600 DTC(s) in the range specified along with history U1xxx DTC(s) are set and the vehicle will start and run, the action is complete.

Did you complete the action?

Go to Step 31

--

31

Did you diagnose all of the DTCs?

Go to Step 32

Go to Step 30

32

Use the scan tool in order to clear the DTCs.

Did you complete the action?

System OK

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