As title, my Furby is blowing its fuse for the rear screen demister as soon as I replace it and turn it on. I'm also getting a bulb warning light occasionally (every 2-3 days at random times), even though all the bulbs seem to be working OK.

Any suggestions where to check before I splash some cash on an auto-electrician.

Check the wiring where it passes from the body to the tailgate. It's not unknown that as the tailgate is opened and closed for the wires to fatigue and break, causing a short circuit. You can usually (carefully) solder the wires back together.

T'was the first place I would have looked, but I wondered if there was a known other fault that might lead me straight to the cause. Thanks anyway !

you need to measure the resistance of the rear window defroster, maybe its too low or shortcircuited and consume more than your fuse

using a normal multimeter to measure the rear window demister will not give a sensible reading,because the resistance is too low. From Ohms law 14 volts ,at 8 amps , resistance should be 14/8 which equals 1.75 ohms. Most multimeters cannot read this low .(the meter leads are about 0.5 ohm to start with).All the horizontal elements are in parallel with each other ,so if one is open circuit,you will still get a very low reading.The only thing the meter will tell you is that the whole element is open circuit ,or intact. I have never heard of the element being short circuit. If it fails on one element (by damage or burning out),the resistance will rise.I would check the relay ,and then the wiring .If you carefully disconnect where the 12 volts connects to both ends of the element ,and fit a 12 volt bulb,that will confirm if you have a supply to it. If whilst disconnected it blows a fuse then relay,and/or wiring are at fault.

Edited 4 December, 200916 yr by AndyPandy