Re: (juve021)
My boost gauge needed +12V as signal to dim itself.
Have used a bit complicated method.
The CenterConsole (MY05) has a light where the cupholders are. This is on, only when all other switches are also lit, switched by the light sensor on the dashboard.
I used its + for some LEDs. Thought it was simple 12V, but it is not because of the Volvo dim-function. Not even if you always have the dim switch fully turned up, i think its a PWM.
To get a nice +12V signal when the instrument light is on, i used a little
relay that was lying around with a capacitor around the coil to buffer the PWM (don't know how big it was sry)
Had the 5V Version of the relay, think the 6V might work best.
Don't use the 12V because there aren't 12V !!!
The relay switches + from Kl.15 (ignition from cig lighter) to generate a +12V light signal
Works flawless!
Hope you understand what i mean and my english is not too bad!
Edit: You can reach the light by pulling off the handbrake bag!
Modified by Scyn at 11:01 PM 4-11-2009