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Discussion Starter · #1 ·
Hi everyone,

The last 2 days I've had the battery warning light on my Cmax 2011 1.6tdci.
I've tested the battery when ignition off, its reading 12.6v
When engine running battery is reading 13.7v. The car isn't struggling to start and haven't noticed any changes expect the warning light illuminates 30 seconds into driving.

Is the alternator faulty as the battery is reading 13.7v? Or maybe something else?

Any help would be much appreciated! :D
 

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Hi Silvermax,
Consulting my Haynes manual - it says
1) check alternator drive belt for tightness,and check connections and the all important earthing points.
2) with the engine running, putting a voltmeter across the battery - you should be getting 13.5 - 14.8 V
3) switching on as many electrical accessories as you can (headlights, heater blower etc) you should still be getting the 13.5 - 14.8V
Sounds like a reasonable test of whether your alternator is working or not
 

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Discussion Starter · #3 ·
Hi Sevenspoke,
Alternator belt is tight
Connections and earthing points look good from what I can see
With all electrical accessories on, battery is reading 13.7v

I've have gotten an error code from obd2 reader saying U0120 Lost Communication with Starter Generator Control Module

Any ideas where do start looking? I'm guessing faulty sensor or wire damage but where to start 🤔
 

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The last bit of the loom to the alternator is the so called smart loom and it did have issues with some max's. Maybe a recall for a change on that part I seem to remember. Have a search.
 

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Discussion Starter · #5 ·
Right quick update,

Alternator doesn't charge when started up idling, only starts charging when revved then will charge at 13.7v even when idling after the initial first rev.

Any idea?!
 
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