25/08/2026 9:08 am
Topic starter
Automotive Q&A
Mercedes EQA 260 cooling warning with Y1/10 open-circuit wording
Review the evidence, add a focused answer, and distinguish confirmed measurements from assumptions.
Notifications
Clear all
Vehicle Questions
2
Posts
2
Users
0
Reactions
108
Views
0
An EQA 260 displayed a cooling-system warning after recent front-end service. The scan report describes an open circuit for component Y1/10, and coolant level is correct. The vehicle still drives, but I have not cleared the fault or started disconnecting components because the thermal system interfaces with high-voltage hardware.
Is Y1/10 diagnosed as a low-voltage coolant valve circuit on this model, and what can be checked without entering the high-voltage system? I have the vehicle-specific wiring information available and want to keep the diagnostic boundary explicit.
1 Answer
0
26/08/2026 8:36 am
Use the VIN-specific component legend and wiring diagram to confirm what Y1/10 denotes on this exact build; do not rely on the label from another Mercedes platform. If the diagram shows a conventional low-voltage valve circuit, you can inspect its accessible connector, terminal seating and harness routing, then test supply and control only with the specified breakout method and command conditions.
That does not authorize opening an orange connector, battery enclosure or high-voltage coolant device. If the procedure crosses the high-voltage boundary, stop and use a qualified EV technician with the required isolation and verification equipment. Given the timing after front-end work, a disturbed low-voltage connector is worth a visual check before replacing the valve.
Topic starter
27/08/2026 10:12 am
The VIN-specific diagram confirmed a low-voltage changeover-valve circuit outside the high-voltage boundary. Its connector was latched visually but one secondary lock had not seated after the front-end work. Reseating it restored the commanded response, the fault cleared normally, and the warning did not return on the thermal-system function test.