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gretafrost89

EQC Anti Theft Alarm System Malfunction

My 2021 Mercedes EQC, electric, is throwing a weird error. I'm getting an anti-theft alarm system malfunction warning. Mileage is at 111877 km. The alarm system isn't working at all now. I scanned it and it shows an error stored in the error memory, related to the alarm system. Could it be something simple, like the alarm system being coded to activate the optical locking indicators?

4 comment(s)

vivienwerner1

That's a tricky one. I had a similar issue years ago with an older vehicle, but the symptoms were different – constant false alarms. Immobilizer problems can manifest in strange ways. Coding issues are possible, but before jumping to conclusions, have you checked the basics? Battery voltage can sometimes cause weird electrical glitches. Also, is the alarm control module getting power? A faulty ground connection can wreak havoc with these systems. It's worth checking those before assuming it's a coding problem.

gretafrost89 (Author)

Thanks for the reply. I did check the battery voltage, it seems fine. When you mention the alarm control module getting power, how would I go about checking that? Is there a specific fuse or relay I should be looking at?

vivienwerner1

Checking the alarm control module's power supply will require a multimeter and access to the wiring diagram for your EQC. I wouldn't recommend poking around unless you're comfortable with electrical testing. A blown fuse is possible, but without the diagram, you're just guessing. Since you've already scanned the car and have an error code, and you suspect a coding issue, it's probably best to take it to a workshop. They have the proper diagnostic tools to pinpoint the exact cause. It sounds like the alarm system is completely non-functional, which does point towards a more serious issue than just a simple fuse.

gretafrost89 (Author)

Alright, I appreciate the advice. I took it to a shop, and you were right. It was a coding issue related to the alarm system activating the optical locking. They recoded it, and it's working fine now. Total cost was 45€. Thanks again!

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