GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Century 🢒 DTC 🢒 DTC U1096 Loss of Communications with IPC

Object Number: 385137 Size: MF
Data Link Connector Schematics

Circuit Description

Class 2 control modules receive a state of health message from the instrument cluster through the Class 2 serial data link.

Conditions for Setting the DTC

Class 2 control modules do not receive a state of health message from the instrument cluster.

Action Taken When the DTC Sets
    • Class 2 control modules store DTC U1096 in memory.
    • The SERVICE VEHICLE SOON indicator lamp turns on.

Conditions for Clearing the DTC
    • DTC U1096 will clear as a current DTC U1096 and will set as a history DTC U1096 when the class 2 control modules detect a state of health message from the instrument cluster.
    • Using a scan tool.

Diagnostic Aids
    • The following conditions may cause an intermittent malfunction to occur:
       - An intermittent open or short to ground in circuit 1036.
       - Poor connections at the instrument cluster.
       - An intermittent open in the Splice Pack SP205.
    • The Body Control Module (BCM) may store DTC U1096 if certain diagnostics are performed between the instrument cluster and the Data Link Connector (DLC).
    • DTC P1626 will set in the Powertrain Control Module (PCM) when the ignition switch is on with the Body Control Module (BCM) disconnected. When BCM diagnostics and repairs are completed, refer to Engine Controls for additional information on PCM related DTCs.

Test Description

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

  1. This step checks for an open in the Splice Pack SP205.

    2.

  2. This step checks for a short to ground in circuit 1036.

    3.

  3. This step checks for a short to B+ in circuit 1036.

    4.

  4. This step checks for an open in circuit 1036.

Step

Action

Value(s)

Yes

No

1

Did you perform the Data Link Communications Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Data Link Communications

2

  1. Turn the ignition switch off.
  2. Disconnect the scan tool from the DLC.
  3. Disconnect battery negative terminal.
  4. Using a DMM, measure the resistance between the SP205 terminal A and each of the SP205 terminals B, E, G, L, and M; one terminal at a time.

Is the resistance measured less than the specified value?

2ohms

Go to Step 3

Go to Step 7

3

  1. Disconnect the instrument cluster harness connector.
  2. Using a DMM, measure the resistance between the SP205 harness connector terminal G and ground.

Is the resistance measured same as the specified value?

Infinite (OL)

Go to Step 4

Go to Step 8

4

  1. Reconnect the battery negative terminal.
  2. Turn the ignition switch on.
  3. Using a DMM, measure the voltage between the SP205 harness connector terminal G and ground.

Is the voltage measured less than the specified value?

2 V

Go to Step 5

Go to Step 9

5
  1. Turn the ignition switch off.
  2. Using a DMM, measure the resistance between the SP205 harness connector terminal G and the instrument cluster harness connector terminal B2.

Is the resistance measured within the specified range?

Less than 5ohms

Go to Step 6

Go to Step 10

6
  1. Reconnect the instrument cluster harness connector.
  2. Turn the ignition switch on.
  3. Using a scan tool, communicate with the instrument cluster.

Does the scan tool communicate with the instrument cluster?

--

Go to Step 12

Go to Step 11

7

Replace the Splice Pack SP205.

Is the repair complete?

--

Go to Step 13

--

8

Repair short to ground in circuit 1036.

Is the repair complete?

--

Go to Step 13

--

9

Repair short to B+ in circuit 1036.

Is the repair complete?

--

Go to Step 13

--

10

Repair poor connection or open in circuit 1036.

Is the repair complete?

--

Go to Step 13

--

11
    • The integrity of the class 2 serial data link is OK. However, the instrument cluster is not communicating class 2 data due to a fault within the instrument cluster.
    • Refer to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Console for further diagnosis.

Is the action complete?

--

Go to Step 13

--

12

The action in intermittent. Refer to the Diagnostic Aids in DTC U1096.

Is the action complete?

--

Go to Step 13

--

13
  1. Turn the ignition switch off.
  2. Reinstall connectors/components removed and verify repairs.

Is the action complete?

--

Go to Diagnostic System Check - Data Link Communications

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