WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
Circuit
Short to Ground
Open/High Resistance
Short to Voltage
Signal Performance
Signal
B2455 04
B2455 04
B2455 04
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Low Reference
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B2455 04
1
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1. OnStar Microphone Inoperative - Caller Cannot Be Heard