Weird Electrical Problem
 

My sunroof and electric windows stop working as soon as the engine is started.

There is 12v at the window switch when the ignition is on, however there is only about 8v when the engine is running. At fuse number 3 there is approx 12v when the engine is off and about 14v with the engine running.

When the engine is off the windows work perfectly so this does not appear to be switch related.

Anyone have any ideas? What would cause the voltage to drop at the switch but only while the engine is running ?

Tks

Did you check some other "user system" to see if there is the same voltage drop ??

Before you get alarmed, do a simple test :
Before you start the car, do a voltage reading at battery and note the value. Once the motor is started, do another voltage reading at the battery. Can you do a test by connecting the window and the sunroof circuit directly to battery (safely, throu out a fuse or someting like that) to see if you problem lies into the delivery of the juice for the circuit concerned ??
truly, Filou.

Problem solved.

The source of the problem is the ignition switch.
Wiggling the key whilst the engine is running enables the windows and sunroof to work.

The fault is a bit unpredictable hence the varying voltage readings.
I have heard that a faulty ignition switch can cause many unpredictable problems. So this is just another example.

Now all I need to do is instaLL a new switch.

Thanks for all your help/support/suggestions.