Volvo All Engines (2004 Emissions) Fault Code: PID 50 FMI 9 AC System Status

Fault Condition: The AC System Status code will set when the Engine Management System (EMS) Module has lost the AC Status ON/OFF Signal from the Vehicle Electronic Control Unit (VECU).

Possible repairs:

1) Verify that code PID 50 is set. If code PID 50 is not set, wiggle the harness and connectors to try to set the code. Visually inspect the VECU connectors and wires for poor connections.
2) Is code MID 144 PID 84, 86, 91 or PSID 8, 9 is set?
If other code(s) MID 144 PID 84, 86, 91 or PSID 8, 9 is set, repair the code(s) MID 144 PID 84, 86, 91 or PSID 8, 9 first then retest the system.
If only MID 128 PID 50 is set, a software problem in the Vehicle Electronic Control Unit (VECU) may exist. Reflashing the Vehicle Electronic Control Unit (VECU) may correct the problem, call MACK Reliability Engineering.

Circuit Description:

The J1587 and J1939 serial data lines are used as the standard communication link for on-board vehicle instrumentation, off-board service diagnostics and fleet management. The vehicle electronic control unit (VECU) is linked to the Engine Management System (EMS) Module via these data lines.