There may be a poor connection issue with the electric engine coolant pump on some 2019-2022 Silverado 1500, Sierra 1500; 2021-2022 CT4 and CT4-V models equipped with the 2.7L turbocharged engine (RPO L3B). The Check Engine MIL may be illuminated and DTC U0672 (Lost Communication with Engine Coolant Pump) may be set.
The electric coolant pump (Fig. 10) is attached to the side of the engine and controls the coolant flow, replacing the conventional belt- or chain-driven pump whose speed is directly coupled to engine speed. The coolant flow from the electric coolant pump is not related to engine speed but is independently controlled by the Engine Control Module to maintain an ideal engine operating temperature during all engine speeds and operating conditions.
Fig. 10
If DTC U0672 is set, check for any coolant pump-related wiring contamination, terminal tension or lock issues that may cause a poor connection and intermittent communication. (Fig. 11)
Fig. 11
If the inspection of the wiring harness and connector does not identify any issues, cycle the electric engine coolant pump connection and clear DTC U0672. If the code resets, refer to the appropriate Service Information to further diagnostics. If the code does not reset, release the vehicle.
Do not replace any parts at this time. During warranty analysis, many coolant pumps that have been replaced have had no trouble found. Further information will be released when available.
Refer to #PIP5863 for additional information.
– Thanks to Raymond Haglund
