W211 visit workshop red battery

foru2justnv

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Joined
May 18, 2011
Messages
53
Location
West sussex
Car
Mercedes w211 E320 CDI s212 e220cdi
Hi all
W211 e320cdi. Had a red warning light on now for a while so thought id buy some new batteries.
Bought a new 019 battery for the rear and a ytx14 for the front.
I have checked the polyfuse and it was good.
Checked the wiring from bcm to polyfuse and the both had continuity. Changed the aux battery relay as they were cheap.

Just today installed smaller battery at front and surprised to see the red battery light hasnt dissappeared.
Have I missed something.
As per instrument cluster ive got good voltage before and after start up.
Any help much appreciated
Tiff
 

whitenemesis

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Lexus RC300h F-Sport 2019
A faulty BCM may trigger the warning , as could a failed alternator regulator pack.

You really need to get the car on STAR and have the codes read..
 
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foru2justnv

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Joined
May 18, 2011
Messages
53
Location
West sussex
Car
Mercedes w211 E320 CDI s212 e220cdi
Hi Thanks for your replies. I have been monitoring the alternator output while driving and also witha voltmeter. Im consistantly getting 14.0v so the alternator checks out fine. Plus its never drained or gone flat since ownership. Previous rear battery was fine I changed it thinking it was that but that was 3 months ago.
 
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foru2justnv

Member
Joined
May 18, 2011
Messages
53
Location
West sussex
Car
Mercedes w211 E320 CDI s212 e220cdi
Will give that a try tomorow. Let you know thanks
 

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