Faulty Engine Coolant Sensor
Engine Coolant Sensor harness is open or shorted
Engine Coolant Sensor circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
Engine cranks but may not start – may be intermittent
May or may not be able to communicate with a scan tool / depends on problem
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for the state of health monitoring/node alive messages. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an identification number is learned by a module, it will monitor for that module node alive message. Each module on the class 2 serial data circuit is required to send a Node Alive message every 2 seconds. When no message is detected from a learned identification number for 5 seconds, a Diagnostic Trouble Code (DTC) U1073 is set.