That's a hoot!
Vauxhall diagnostics checks rear screens!
My Vaux OP com doesn't but then again mines 2013 so maybe the new ones do.
Doubt it though.
Anyhoo you've made a decent start your self.
Now what I do is use a doodad called a power probe,
connects to the battery and a button on the thing output either battery V or ground neg.
So I'd output battery V to the screen feed and see if the grid powers up,
or connect to the ground side and look for same.
So either buy a power probe,
A cheap Sealey on is less than £20 on Ebay.
Or you can run a jump wire from the battery pos to the screen pos
Just temporary,
See if it works.
Same with the ground.
Battery Neg to screen negative.
The advantage with a power probe is it can be moved safely from point back down the wire say from the screen if it work you would move the probe point back to the next connector and so on until it doesn't work the screen and you would have narrowed down where the short circuit is.
Really simple to use tool and a lot cheaper than either Vaux or an auto spark.
Posted Nov 21, 2016 (8 years ago)