This bulletin applies to 2020 GMC Acadia vehicles equipped with a 2.0L engine and 2019-2020 Sierra 1500 (new model) vehicles equipped with a 2.7L engine.
DTC P3075 or P3076 may be set as current or in history. It is possible that the cooling system is low on coolant or that air may be trapped in the system. If you encounter this condition, complete the following steps. Do not replace the coolant pump assembly at this time.
Pressure test the cooling system to confirm that no leaks are present. Repair leaks as needed. Once the coolant leak has been repaired, refer to the latest Cooling System Draining and Filling procedure in the service manual for fill and bleeding instructions.
Once the engine is started after the fill procedure, it is possible that DTC P3075 may reset until all air is purged from the system. At this point, any codes should be cleared. The engine should be at operating temperature and the vehicle road tested to completely purge any remaining air from the system.
The diagnostic test will run once per ignition cycle if all enable conditions are met per service instructions. The intrusive diagnostic will run the coolant pump at roughly 4000 rpm for 15 seconds and evaluates the pump motor AC current to be within expected range. The coolant pump AC current feedback will be lower if the cooling system is leaking or low on coolant. Using GDS, confirm the P3075 has run and passed in the current drive cycle to ensure that the diagnostic has executed and no fault is detected before releasing the vehicle to the customer. If the vehicle returns for a second time with DTC P3075, replace the coolant pump assembly.
