2011 CS PCM display brightness won't change

[Tom M]

I just picked up a new to me 2011 CS and can't seem to get the PCM screen to change brightness so it was a major pain driving it home tonight with the glare. I followed the procedure in the manual but it doesn't seem to make any difference.

Choosing the brightness of the display

    Press the CAR button.
    Press the OPTION button or touch the tab of the same name in the header.
    Select "SET PCM system"
    > "Display PCM"
    > "Screen"
    > "Brightness".

I tried "Automatic" as well as Night Mode and it stayed on what I would consider a daylight setting. Hopefully I'm missing something obvious here as the dealer checklist shows everything works and when I inspected the vehicle it was light out so I didn't notice the issue.

[Tom M]

This seems to have been related to the battery voltage. I charged the battery over the course of several days using a CTEK 3300 and it now seems to work. At least it changes brightness manually - I haven't driven it when it's been dark since charging it.

Edited February 4, 2015 by Tom M

[Tom M]

Well, it does switch between day & night modes but the brightness level won't change. I can scroll up & down from +6 to -6 and the display stays the same brightness. This is even true after I had the PCM unit upgraded to v2.47. Is there a way to reset this somehow? I seem to recall reading a post somewhre but can't remember where it was.

[wvicary]

I haven't heard of this fault before, can only suggest you return to a OPC and have them scan the unit for faults.

[Tom M]

There aren't any faults but I did talk to the service manager at the selling dealer today and he's going to check with Porsche. Unfortunatley it's a 2+ hour drive to there so I'm trying to avoid that if possible. If they come up with a probable fix that is just using the computer I'll visit the local dealer to see if I can get it done.