What type of engine monitors do you have? EMS (tach, quad gauge and alarm annunciator)? MPD (single screen) or something else?
Cat electronically controlled engines typically use either the cat data link or J1939 can bus to communicate to the engine monitor. They are both two wire networks that run up to the dash via the customer connector/wire harness. A broken wire on the op sensor or speed sensor will trip an alarm so I would start by checking and cleaning the customer connector and pins. It is a deutsch 40 pin connector usually in front of the turbo. From there check the connectors on the back of the engine monitors behind the dash. The EMS system has separate connectors that run from the annunciator (which is the brain of the system) to the quad gauge and tach. MPD is a single 24 pin connector.
Your other option is to swap the harness connectors going into the monitors. If the problem stays with the monitor then you have narrowed it down.
This just popped on boatdiesel. Sounds similar to what you describe
Cat electronically controlled engines typically use either the cat data link or J1939 can bus to communicate to the engine monitor. They are both two wire networks that run up to the dash via the customer connector/wire harness. A broken wire on the op sensor or speed sensor will trip an alarm so I would start by checking and cleaning the customer connector and pins. It is a deutsch 40 pin connector usually in front of the turbo. From there check the connectors on the back of the engine monitors behind the dash. The EMS system has separate connectors that run from the annunciator (which is the brain of the system) to the quad gauge and tach. MPD is a single 24 pin connector.
Your other option is to swap the harness connectors going into the monitors. If the problem stays with the monitor then you have narrowed it down.
This just popped on boatdiesel. Sounds similar to what you describe
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