For 1990-2009 cars

### Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle , prior to using this diagnostic procedure.

### Circuit/System Description

The SIC gauge assembly receives information from the SIC interface module (SIC Module) located at the rear of the SIC assembly. The SIC module receives data from the body control module (BCM) via high speed GMLAN. The SIC module then translates this data and re-transmits to the SIC gauge assembly via serial data.

### Diagnostic Aids

• | Verify that no other DTCs are present, if any other DTCs are present diagnose those DTCs prior to continuing with this test. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

• | There is no component testing available for the binnacle gauges, if a single gauge is not operating correctly replace that gauge refer to Oil Temperature, Oil Pressure, and Voltmeter Gage Replacement .

### Reference Information

#### Scan Tool Reference

Control Module References

### Circuit Verification

1. Ignition ON, turn headlamps on and operate the dimmer control observing the binnacle gauges, the illumination of the gauges should change with dimmer operation.

⇒ | This test verifies that the ignition power circuit and the ground circuit to the binnacle gauges are operating correctly.

2. Ignition OFF, vehicle at normal operating temperature on level ground. Ignition on, compare the scan tool parameters to binnacle gauges readings.

⇒ | This test verifies that the binnacle gauges are operating correctly.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the binnacle interface module.
2. Ignition ON, connect an approved test lamp between the power circuit and a known ground.

⇒ | If the test lamp does not illuminate, test for a short to ground or an open/high resistance on the power circuit.

3. Ignition OFF, disconnect the harness connector at the binnacle interface module.
4. Ignition ON, connect an approved test lamp between the ignition circuit and a known.

⇒ | If the test lamp does not illuminates, test for a short to ground or an open/high resistance in the ignition circuit.

5. Ignition OFF, test the GMLAN circuits for open/high resistance.
6. If all circuits test normal, replace binnacle interface module.

### Repair Instructions

Perform the Diagnostic Repair Verification .