Schematic Reference: Data Link Connector Schematics

Did you review the Head Up Display (HUD) Description and Operation and perform the necessary inspections?

Go to Step  2

Go to Symptoms - Instrument Panel, Gages and Console

Is the vehicle equipped with OnStar?

Go to Step 3

Go to Step 4

1. Turn the ignition ON, with the engine OFF.
2. Turn the radio ON.
3. Set the volume to a comfortable level.
4. Activate the OnStar center call button.

Does "Connecting to OnStar" play through the system and mute the radio when played?

Go to Step 4

Go to No (or Noisy) OnStar Audio in Cellular Communication

Test the Entertainment and Comfort serial data circuit for an open or for a short between the radio and the HUD. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 5

1. Turn the ignition OFF.
2. Disconnect the HUD.
3. Turn the ignition ON.
4. Turn the radio ON.
5. Using the frequency function of the DMM, check for any frequency present on the entertainment and comfort serial data circuit at the data link connector while adjusting the radio tuner.

Does DMM display a frequency?

Go to Step 6

Go to Step 7

Inspect for poor connections at the harness connector of the HUD. 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 10

Go to Step 9

Inspect for poor connections at the harness connector of the radio. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

Replace the radio. Refer to Radio Replacement in Entertainment.

Did you complete the replacement?

Go to Step 10

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Replace the HUD. Refer to Head Up Display Module Replacement .

Did you complete the replacement?

Go to Step 10

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step  2