The U1501 and U1510 diagnostic trouble codes (DTCs) in a Chevy Silverado often indicate a problem with the Local Interconnect Network (LIN) bus communication. This article details a real-world diagnosis and repair of these codes in a 2017 Silverado LTZ 6.2, focusing on the Active Grille Shutter Motor Module as the root cause.
The vehicle presented with a Check Engine Light (CEL) and no other noticeable drivability issues. A code scan revealed the U1501 and U1510 codes, both pointing to a LIN bus communication fault within the Powertrain Control Module (PCM). Research indicated a potential faulty ground (G102) associated with the U1510 code and possible intermittent right front headlight issues. However, the vehicle owner reported no lighting problems. Despite this, the G102 ground was inspected and tested. Although appearing rusty, the ground measured a normal 50mV under load, eliminating it as the source of the problem.
Referring to the LIN bus network diagram, it was determined that the only module communicating with the PCM on this specific LIN bus was the Active Grille Shutter Motor Module. This significantly narrowed down the potential causes.
To further diagnose the issue, the technician accessed connector X132 located behind the front grille, specifically targeting the GREEN/VIOLET communication wire. A digital oscilloscope was connected to observe the LIN bus waveform. Initially, the waveform appeared normal. However, closer inspection revealed the bus voltage was only being pulled down to around 7 volts instead of the expected battery voltage (around 12 volts). This deviation suggested a problem within the circuit.
To isolate the issue, connector X132 was disconnected and the waveform was re-checked. With the connector disconnected, the bus voltage pulled down to the expected battery voltage, indicating the problem resided downstream of X132 – likely within the Active Grille Shutter Motor Module, its wiring, or its power/ground supply.
Subsequent load testing confirmed the power and ground circuits to the shutter module were functioning correctly. This led to the conclusion that the Active Grille Shutter Module itself was faulty. Replacing the module resolved the issue and cleared the U1501 and U1510 codes.
In conclusion, diagnosing LIN bus communication errors requires a systematic approach, including understanding network diagrams, utilizing diagnostic tools like oscilloscopes, and performing thorough testing procedures. In this case, a faulty Active Grille Shutter Motor Module was the root cause of the U1501 and U1510 codes in the 2017 Chevy Silverado. The diagnostic process outlined here demonstrates the importance of methodical troubleshooting to accurately pinpoint and resolve complex vehicle issues.
