GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The IPC and the body control module (BCM) communicate via a serial peripheral interface (SPI). The IPC receives information from the BCM on the SPI serial data out circuit. The BCM transmits information to the IPC in order to control various indicators, the engine coolant temperature gage, and the fuel gage. The BCM receives data from the IPC on the SPI serial data in circuit. The IPC transmits information such as tachometer active status, speedometer active status, and invalid data received messages. The BCM synchronizes the data signals by toggling the SPI serial data clock circuit to ground.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

U2000

The IPC determines that the BCM transmitted data to the IPC is invalid for greater than 12 seconds. The IPC sends a message to the BCM via the SPI serial data in circuit indicating that invalid data was received.

U2001

The BCM determines that the IPC transmitted data to the BCM is invalid for greater than 5 seconds.

U2002

The BCM detects that the SPI serial data in circuit is less than 1.2 v for greater than 5 seconds.

U2003

The BCM detects that the SPI serial data in circuit is greater than 4.5 v for greater than 5 seconds.

U2004

The BCM detects that the SPI serial data out circuit is less than 1.2 v for greater than 5 seconds.

U2005

The BCM detects that the SPI serial data out circuit is greater than 4.5 v for greater than 5 seconds.

U2006

The BCM detects that the SPI serial data clock circuit is less than 1.2 v for greater than 5 seconds.

U2007

The BCM detects that the SPI serial data clock circuit is greater than 4.5 v for greater than 5 seconds.

Action Taken When the DTC Sets

U2000, U2004, U2005, U2006, U2007

The IPC takes the following default action:

    • The fuel gage displays empty.
    • The engine coolant temperature gage displays 100°F.
    • The theft system indicator, ABS indicator, and SERVICE VEHICLE SOON indicator illuminate.

Conditions for Clearing the DTC

    • The current DTC clears on the next malfunction free ignition cycle.
    • The history DTC clears after 100 malfunction free ignition cycles.
    • The BCM receives a clear DTC request from the scan tool.

Step

Action

Value(s)

Yes

No

Schematic Reference: Instrument Cluster Schematics

1

Did you perform the Instrument Cluster Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

Does the scan tool display DTC U2001?

--

Go to Step 3

Go to Step 5

3

Does the scan tool display DTC U2004?

--

Go to Step 10

Go to Step 4

4

Does the scan tool display DTC U2006 or U2007?

--

Go to Step 6

Go to Step 7

5

  1. Turn OFF the ignition.
  2. Disconnect the BCM connector C3.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the SPI serial data out circuit to a good ground.

Does the voltage measure greater than the specified value?

9.0 V

Go to Step 9

Go to Step 12

6

  1. Turn OFF the ignition.
  2. Disconnect the BCM connector C3.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the SPI serial data clock circuit to a good ground.

Does the voltage measure greater than the specified value?

9.0 V

Go to Step 8

Go to Step 13

7

  1. Turn OFF the ignition.
  2. Disconnect the IPC connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the SPI serial data in circuit to a good ground.

Does the voltage measure greater than the specified value?

9.0 V

Go to Step 14

Go to Step 15

8

Test the SPI serial data clock circuit 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 20

Go to Step 17

9

Test the SPI serial data out circuit 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 20

Go to Step 17

10

Test the ignition 0 voltage circuit of the IPC for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 11

11

Test the battery positive voltage circuit of the IPC for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 16

12

Test the SPI serial data out circuit for an open, a high resistance 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 20

Go to Step 16

13

Test the SPI serial data clock circuit for an open, a high resistance, 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 20

Go to Step 16

14

Test the IPC electrical ground circuit for an open or a high resistance and the SPI serial data in circuit 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 20

Go to Step 16

15

Test the SPI serial data in circuit for an open, a high resistance, 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 20

Go to Step 17

16

Inspect for poor connections at the harness connector of the IPC. 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 20

Go to Step 18

17

Inspect for poor connections at the harness connector of the BCM. 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 20

Go to Step 19

18

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the replacement?

--

Go to Step 20

--

19

Important: Perform the set up procedure for the replacement BCM.

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

--

Go to Step 20

--

20

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK