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CKpt

Strange Electrical Problem

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I've had my 451 for 5 months now and it has never missed a beat, until monday...After a short trip (1Km) the car started beeping, indicators flashing, telling right door open, left door open. I stopped, turned it off, opened and closed both doors and turned it on again. Still the same...Got home, tried closing the car - it doesn't - the boot won't close/open, it doesn't even make noise. The soft top doesn't seem to be working either - it clicks - but no movement.Called smart - Technician came, checked fuses, turned the alarm off, took the battery out, still no results. The car drives well but beeps all the time and the hazards are on all the time. I've also noticed the hill-hold function doesn't work too.The car has been at Mercedes since 10PM on Monday... They've managed to open the boot with the diagnostics computer(?) and the car started operating normally; they went for a test-drive, the issue popped up again.First they said it could be related to the alarm (installed there); now they've been washing the car to see if there's any water ingress...Strange thing is the car has been washed a few times in the 5 months I've owned it, It caught rain, etc, etc, etc... And this fault happens in the driest, must sunny period we've had in months.

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First they said it could be related to the alarm (installed there); now they've been washing the car to see if there's any water ingress...

Is this an OEM or aftermarket alarm? If aftermarket, I would say with 90% certainty that is the culprit.Step 1 in diagnosing weird electrical issues like this is to look for, find and remove all aftermarket electronics. Most of the time that solves the issue.

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Is this an OEM or aftermarket alarm? If aftermarket, I would say with 90% certainty that is the culprit.Step 1 in diagnosing weird electrical issues like this is to look for, find and remove all aftermarket electronics. Most of the time that solves the issue.

Aftermarket, installed by Mercedes themselves.Latest Updates: No water Ingress whatsoever. The issue seems to happen when going over bumps/ on bumpier roads. The issue seems to be coming from the alarm but they can't find the culprit, a dodgy wire or something.

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The only thing I can suggest is to totally disconnect the aftermarket alarm system (wiring) and give it another try. If it sorts itself out, great! If not, then all I can do is wish you "good luck".

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Thanks for the replies... I've already told them to do that but they seem a bit hesitant in trying it. Let's hope it's just the alarm...

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Thanks for the replies... I've already told them to do that but they seem a bit hesitant in trying it. Let's hope it's just the alarm...

Just to give closure to this topic... It seems the main culprit was the alarm module, which led the SAM unit and Tachometer to be replaced. Mercedes don't know why, or how this happened.

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