GM Service Manual Online
For 1990-2009 cars only

Object Number: 427808  Size: SF

Circuit Description

This code (both current and history) indicates the body control module (BCM) has sensed a short to the ground/open condition on the instrument cluster serial peripheral interface (SPI) data out line to the BCM.

Conditions for Setting the DTC

All of the following conditions must be met:

    • Ignition 0 is active.
    • The serial data SPI clock line from the BCM to the IPC is shorted to ground for 5 seconds.

Action Taken When the DTC Sets

    • Stores DTC U2006 in the BCM memory
    • The instrument cluster illuminates the following indicators:
       - THEFT SYSTEM
       - ABS
       - SERVICE VEHICLE SOON
       - The PRNDL indicator is blank.
       - The temperature gauges read zero.
    • Disables the instrument cluster data output

Conditions for Clearing the DTC

    • The BCM goes to sleep and reinitializes with the malfunction cleared.
    • Use the scan tool.

Diagnostic Aids

    • With the ignition switch in the ON position, test for voltage transitions on the SPI data line.
    • When the diagnostics direct you to take electrical measurements at the wiring harness junction blocks, refer to Power and Grounding Component Views in Wiring Systems.
    • If the DTC is a history DTC, the problem may be intermittent. Perform the above tests while wiggling the wiring and connectors. This may often cause the malfunction to appear.

Test Description

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

  1. This step determines if the body control module (BCM) is malfunctioning.

  2. This step determines if there is an open in CKT 1323 between the instrument cluster and the BCM.

  3. This step determines if there is a short to ground in CKT 1323 between the instrument cluster and the BCM.

Step

Action

Value(s)

Yes

No

Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.

1

Was the BCM System Check performed?

--

Go to Step 2

Go to Body Control Module System Check

2

  1. Disconnect the BCM connector C3.
  2. Turn the ignition switch to the ON position.
  3. Use the J 39200 Digital Multimeter in order to measure the voltage at the BCM harness connector C3 terminal A7.

Does the voltage equal the specified value?

Battery Voltage

Go to Step 3

Go to Step 6

3

Inspect for a poor connection at the BCM connector C3 terminal A7.

Was a poor connection found?

--

Go to Step 4

Go to Step 5

4

Repair the poor connection at the BCM connector C3 terminal A7. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 13

--

5

Replace the BCM. Refer to the following procedures:

    •  Body Control Module (BCM) Programming/RPO Configuration in Body Control Systems
    •  Body Control Module Replacement in Body Control Systems

Is the repair complete?

--

Go to Step 13

--

6

  1. Disconnect the instrument cluster connector.
  2. Use the J 39200 DMM in order to measure the resistance in CKT 1323 between the BCM connector C3 terminal A7 and instrument cluster connector A10.

Is the measured resistance within the specified range?

0-2 ohms

Go to Step 7

Go to Step 8

7

Use the J 39200 DMM in order to measure the resistance in CKT 1323 between the BCM connector C3 terminal A7 and ground.

Does the measured resistance equal the specified value?

0L

(Infinite)

Go to Step 10

Go to Step 9

8

Repair the open in CKT 1323 between the BCM connector C3 terminal A7 and the instrument cluster connector A10. Refer to Wiring Repairs in Wiring Systems.

Is the CKT repair complete?

--

Go to Step 13

--

9

Repair the short to ground in CKT 1323 between the BCM connector C3 terminal A7 and the instrument cluster connector A10. Refer to Wiring Repairs in Wiring Systems.

Is the CKT repair complete?

--

Go to Step 13

--

10

Inspect for a poor connection at the instrument cluster connector terminal A10 CKT 1323.

Was a poor connection found?

--

Go to Step 11

Go to Step 12

11

Repair the poor connection at the instrument cluster connector terminal A10. Refer to Wiring Repairs in Wiring Systems.

Is the CKT repair complete?

--

Go to Step 13

--

12

Replace the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

--

Go to Step 13

--

13

Clear the DTCs from the memory.

Are the DTCs cleared from the memory?

--

Go to Body Control Module System Check

--