SC rear defroster malfunction

My 2010 Lexus SC, gasoline engine, has a rear window heating malfunction. The error memory reports a fault, and windshield heating is also impaired. Diagnostics suggest a heavily discharged or defective battery. Mileage is 128811 km. Has anyone experienced similar rear defroster issues?

4 comment(s)

I had a similar issue on my SC. The rear window heating coil wasn't working, and I was getting errors. Check your battery first, a weak battery can cause all sorts of electrical gremlins in these cars. Did you check the thermal window fuse?

Thank you for the quick response. I did check the fuse, it appears to be intact. Could a weak battery truly cause such a specific failure in the window demister circuit? Is there a specific voltage threshold I should be looking for?

Yes, a weak battery can definitely cause that. The rear window heating and windshield heating draw a lot of power. If the voltage drops too low, the system might throw an error and shut down. I'd suggest taking it to a workshop to get the battery properly tested, and maybe the charging system too.

Understood. Thank you for confirming my suspicions. I will proceed with a battery replacement. The workshop confirmed the battery was defective and performed the replacement; the rear window heating is now functional. Total cost was 290€.

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