Description:

The error code ETC 001549.03 is triggered when the control unit measures excessive voltage at the motor connecting leads 2016 and/or 2027 of the heater valve (B131). This indicates that the circuit is shorted to a supply lead.

Reaction:

When this fault is detected, the control unit may disable or limit the operation of the heater valve to prevent damage due to overvoltage. This can result in the malfunction of the heater valve, affecting the heating system’s performance.

Recommendations:

Inspect Electrical Circuits:

• Check for Shorts to Supply Lead: Inspect the wiring and connectors for signs of short circuits to the supply lead. Look for damaged insulation or exposed wires.
• Measure Voltage: Use a multimeter to measure the voltage at the motor connecting leads (2016 and 2027) to ensure it is within the specified range.

Test and Replace Components:

• Test Heater Valve Motor: Verify the operation of the heater valve motor. Replace the motor if it is found to be malfunctioning due to overvoltage.
• Inspect Control Unit: Ensure that the control unit is functioning correctly. Replace the control unit if it is found to be faulty.

Repair or Replace Wiring:

• Fix Damaged Wiring: Repair or replace any damaged or shorted wiring in the heater valve circuit. Ensure all connections are secure and properly insulated.

Note:

Regular maintenance and inspection of the electrical system can help prevent issues related to overvoltage. Ensuring proper routing and securing of wires can reduce the risk of shorts and enhance system reliability.