U0672

Code

Generic U — Network/User

Lost Communication With Engine Coolant Pump

Brand: Generic

Type: U — Network/User

Views: UK: 20 EN: 62 RU: 19

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Page language: EN

Open or shorted wiring between pump and network/CAN bus
Corroded, loose or damaged connector at pump or wiring harness
Blown fuse or faulty relay feeding pump/module
Faulty engine coolant pump control module or integrated pump assembly
Network (CAN/LIN) bus fault: short to battery/ground, missing termination, damaged wiring
Low battery voltage or poor ground affecting module operation

DTC U0672 stored (communication fault) and possibly other network U-codes
Engine coolant pump may not run on command or operates intermittently
Cooling system warnings or rapid coolant temperature rise/overheat
Possible reduced engine power, limp-home mode, or HVAC/cooling anomalies
No module data or “no response” when querying the coolant pump module with a scan tool

Retrieve all stored/active DTCs and freeze frame data from all modules
Check battery voltage and ground at time of failure and during inspection
Visually inspect wiring and connectors at the coolant pump and along the harness for damage/corrosion
Check fuses and relays related to the pump and its controller
Use a scan tool to attempt to communicate with the coolant pump module and view live CAN messages
Check other modules on the same bus for communication problems to determine if bus-wide fault exists

CAN High voltage (key ON, engine OFF) ~2.5 V typical
CAN Low voltage (key ON, engine OFF) ~2.5 V typical
Bus differential idle ~0 V, dominant/recessive voltages under load per spec
Message ID(s) for coolant pump module and expected message frequency (messages/sec)
Supply voltage to pump/module (battery voltage when key ON)
Circuit ground resistance at pump/module (low ohms)

Record all DTCs and freeze-frame data from all modules; note occurrence conditions.
Verify battery state-of-charge and good chassis/engine grounds; low voltage can cause comm faults.
Visually inspect pump connector and harness for corrosion, bent pins, water intrusion, or physical damage; repair as needed.
Check fuses/relays for pump power and controller power; replace if blown or intermittent.
With a capable scan tool, try to communicate with the coolant pump module. Note whether it responds and whether it publishes expected CAN messages.
Measure CANH and CANL voltages with key ON; if grossly out of range, isolate bus to find shorted stub or damaged harness.