Parking Brake – See Operator’s Manual” + “Blind Spot Assist Inoperative

Jan 13, 2026 | 07:33 PM

Manny Pineda

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Joined: Jul 2020

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Mercedes SLK R171 2007 & GLA 250 2018

Parking Brake – See Operator’s Manual” + “Blind Spot Assist Inoperative

Hello everyone,

I’m looking for guidance from Mercedes-experienced owners or technicians regarding an intermittent electrical issue on my vehicle. Ive searched this problem on the forum and haven't found any information.

Vehicle details:

Model: Mercedes-Benz GLA 250 Year: 2018 Chassis: X156

I am getting two alerts at the same time, intermittently:

“Parking Brake – See Operator’s Manual”
“Blind Spot Assist Inoperative”

Important details about the behavior:

The vehicle itself does NOT shut off.
Only the alerts appear and then disappear on their own. Usually when starting the car back up.
Sometimes they stay on for days, then once you start the car in the morning they don't come on.
When the alerts turn off, both systems appear to function normally again.
The alerts have been intermittent since before any work was done.

What has already been checked / done:

The Front SAM (A1569005303) was removed and carefully cleaned due to visible corrosion/sulfation on part of the board and connectors.
The cleaning did NOT change the behavior of the problem at all.
The alerts still come and go exactly as before.
No other electrical systems (lights, wipers, windows, cluster, etc.) are malfunctioning.
There are no permanent failures, only intermittent ones.

Additional observations:

Because both systems fail together and then recover together, it seems like a shared dependency issue (ESP / wheel speed / voltage / CAN), rather than two independent failures.
Sometimes the alerts clear themselves without cycling the ignition, it does not feel like a hard module failure.
The SAM did have corrosion, but the lack of any behavioral change after cleaning raises doubts that it is the root cause.

Current questions:

Has anyone experienced this exact combination of intermittent EPB + Blind Spot errors on a GLA / CLA / A-Class?
In your experience, when a SAM is truly the cause, do the errors usually stay permanent rather than intermittent?

Shouldn't there be more alerts from other modules that the SAM communicates with if the problem was the SAM?

I am trying to avoid replacing expensive modules without clear evidence and would appreciate insight from anyone who has seen this pattern before. Chatgpt is telling me its most likely not the SAM module, but the workshop is telling me it is cause the SAM had sulfation, but they don't seem to be 100% sure.

Thank you in advance for any technical input or shared experience.