For 1990-2009 cars
Master Electrical Component List
OnStar Schematics

### Circuit Description

The navigation antenna is connected to the vehicle communication interface module (VCIM) with an RG-174 coax cable. The VCIM polls the data from the navigation antenna once every second.

### Conditions for Running the DTC

• | The ignition must be in the RUN or ACC position.

• | The system voltage is at least 9.5 volts and no more than 15.5 volts.

• | All the above conditions are present for greater than 1 second.

### Conditions for Setting the DTC

• | The VCIM does not detect a navigation signal.

• | All the above conditions are present for greater than 1 second.

### Action Taken When the DTC Sets

• | The OnStar® status LED turns RED.

• | The OnStar® Call Center cannot locate the vehicle.

### Conditions for Clearing the DTC

• | The VCIM detects the presence of a navigation antenna.

• | A history DTC clears after 50 malfunction free ignition cycles.

• | The VCIM receives the clear DTC command from the scan tool.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: OnStar Schematics Connector End View Reference: Cellular Communication Connector End Views
1 | Did you perform the Cellular Communication Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Cellular Communication
2 | Notice: Using a DMM to measure the resistance of the navigation antenna coax from the center conductor to the outer shield while the antenna is still connected will damage the navigation antenna.

1. Disconnect the navigation antenna coax connector from the navigation antenna.
2. Disconnect the navigation antenna from the vehicle communication interface module (VCIM).
3. Measure the resistance from the center conductor of the coax to the metal outer shield.

Does the meter read out of limits?

--

Go to Step 3

Go to Step 4

3 | Measure the resistance of the navigation antenna coax center conductor from end to end. Does the resistance measure greater than the specified value? | 1.0 ohms | Go to Step 4 | Go to Step 5
4 | Replace the navigation antenna coax. Did you complete the replacement? | -- | Go to Step 7 | --
5 | Inspect for poor connections at the navigation antenna and the harness connector of the VCIM. 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 7 | Go to Step 6
6 | Replace the Navigation antenna. Refer to Navigation Antenna Replacement . Is the repair complete? | -- | Go to Step 7 | --
7 |

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 8

System OK

8 | Important: Perform the OnStar® setup procedure. Replace the VICM. Refer to Communication Interface Module Replacement .

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

--