For 1990-2009 cars
Data Link Communications Components
Data Link Connector Schematics

### Circuit Description

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

### Conditions for Setting the DTC

All of the following conditions must be met:

• | Ignition 0 is active.

• | The serial data line from the BCM to the instrument panel cluster (IPC) is shorted to ground or open for 5 seconds.

### Action Taken When the DTC Sets

• | Stores DTC U2004 in the body control module (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.

### Conditions for Clearing the DTC

• | The body control module (BCM) goes to sleep and reinitializes with the malfunction cleared.

• | All the body control module (BCM) history codes will be cleared after 100 ignition cycles (from OFF to ON) with no current codes active during the 100 ignition cycles.

• | Use the scan tool.

### Diagnostic Aids

• | Diagnose DTCs U2000, U2006 and U2007 before diagnosing DTC U2004.

• | 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 .

• | If the DTC is a history DTC, the problem may be intermittent. Perform the above tests while wiggling the wiring and connectors. This often causes the malfunction to appear.

### Test Description

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

1. This step determines if the BCM is malfunctioning.

2. This step determines if there is an open in CKT 1321 between the BCM and the instrument cluster.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the body control module (BCM) system check performed? | -- | Go to Step 2 | Go to Body Control Module System Check
2 |

1. Turn the ignition switch to the ON position.
2. Disconnect the BCM connector C3.
3. Use the J 39200 digital multimeter in order to measure the voltage at the BCM harness connector C3 terminal A3 CKT 1321.

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 A3 CKT 1321. Was a poor connection found? | -- | Go to Step 4 | Go to Step 5
4 | Repair the poor connection at the BCM connector C3 terminal A3. Refer to Wiring Repairs . Is the repair complete? | -- | Go to Step 13 | --
5 | Replace the BCM. Refer to the following procedures:

• | Body Control Module (BCM) Programming/RPO Configuration

• | Body Control Module Replacement in Instrument Panel, Gauges and Console

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 1321 between the instrument cluster connector terminal A9 and the BCM connector C3 terminal A3.

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 1321 between the BCM connector C3 terminal A3 and ground. Does the measured resistance within the specified range? | OL (Infinite) | Go to Step 10 | Go to Step 9
8 | Repair the open in CKT 1321 between the BCM connector C3 terminal A3 and the instrument cluster connector terminal A9. Refer to Wiring Repairs . Is the repair complete? | -- | Go to Step 13 | --
9 | Repair the short to ground in CKT 1321 between the BCM connector C3 terminal A3 and the instrument cluster connector terminal A9. Refer to Wiring Repairs . Is the repair complete? | -- | Go to Step 13 | --
10 | Inspect for a poor connection at the instrument cluster connector terminal A9 CKT 1321. Is a poor connection found? | -- | Go to Step 11 | Go to Step 12
11 | Repair the poor connection at the instrument cluster connector terminal A9. Refer to Wiring Repairs . 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 | --