U1041

Circuit Description
The class 2 circuit connects to various modules. These modules monitor the link for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules on the data link. When a module receives a critical operating parameter from another module, the receiving module records the identification number from the module that sent the message. This is called State of Health Monitoring (SOH). A critical operating command will have the sending module's identification number attached with it. Once an identification number is learned by a module, it will continue to monitor for that number. When no message is detected from a learned identification number for a set time, a code is set in the module that was monitoring the identification number.

Conditions for Running the DTC
^ The ignition voltage is greater than 9.5 volts, but less than 18.0 volts.
^ DTCs U1300 and U1301 are not set.

Conditions for Setting the DTC
^ A message from a learned identification number is not detected.
^ All conditions met for 5.0 seconds.

Action Taken When the DTC Sets
^ The PCM stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

Conditions for Clearing the MIL/DTC
^ A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
^ Use a scan tool in order to clear the MIL/DTC.

Diagnostic Aids
This DTC will not set unless the modules have already established communications.