Conditions for Setting the DTC

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

During the Key ON test the ECM detects high voltage on the generator turn on signal circuit for 5 seconds.
With the engine running the ECM detects low voltage on the generator turn on signal circuit for 15 seconds.