What initial troubleshooting measure should be taken if a non-PUC engine fails to go into pump mode?

When a non-PUC (Pump and Utility Compatible) engine fails to go into pump mode, the initial troubleshooting measure should involve checking the operation of the parking brake and the associated interlock mechanism.

The parking brake is designed to prevent the vehicle from engaging certain operations, including pumping, while it is not securely parked. The interlock system is a safety feature that ensures the pump cannot be activated unless specific conditions are met, such as the parking brake being applied. If the parking brake is not functioning properly or if there is an issue with the interlock system, it will inhibit the engine from transitioning into pump mode to prevent any unsafe operation.

This could be crucial in preventing accidental movement of the vehicle while performing pump operations, which could endanger personnel or equipment. Thus, ensuring that the parking brake and interlock are operational is a logical and necessary first step in troubleshooting this situation.

Other measures, while important for overall engine functionality, are secondary when specifically addressing the inability to engage pump mode. Checking the fuel level, oil pressure, or battery charge are valid checks but do not directly relate to the immediate operational concerns governed by the parking brake and interlock system in this scenario.