Diagnostic trouble code (DTC) information ECM-800B

Condition 

Fig 1: Identifying Main Relay

Courtesy of VOLVO CARS OF NORTH AMERICA.

The engine control module (ECM) checks the function of the system relay. The diagnostic trouble code (DTC) is stored if the engine control module (ECM) registers that the voltage from the system relay is too low when the relay is activated.

The diagnostic trouble code (DTC) can be diagnosed when the ignition is switched on.

Substitute Value 

• None.

Possible Source 

• Contact resistance in the terminals
• Open-circuit in the signal cable for the system relay
• Damaged system relay.

Fault symptom[s] 

• The engine does not start.