200 TDi Electrical Fun

[Timbob]

Greetings all. I appreciate the solution to this problem is most likely obvious but it is driving me spare! My horn, interior light and headlamp flasher wont work. I am aware that this is a shared circuit, fuse ok, power at fuse point, no power at interior light, no power at horn.(I can only find one wire to horn, no earth? Does it earth through mounting?) I know it is probably a bad earth or connection, but where? Ive wasted an entire day taking it to bits and getting nowhere. Is there a relay on this circuit? My understanding of the physics of electrics is poor. I only know what ive fixed. Please, any suggestions or advice would be gratefully received.
Thanks, Tim

[unknownmanxman]

Have you put a test meter on the fuse?

[muddysteve]

be warned that circuit runs all over the place (purple wire)

i had a problem with the fuse blowing making the horn,stereo,headlamp flash etc not work


turned out to be a short on the loom by the rear crossmember where the loom exits the chassis and goes up into the tail light cluster

[Timbob]

Thanks for your replies, I have put a multimeter across the fuse point and had 12V. So feasibly the fault could even be at the back of the vehicle? Ive had real trouble tracing everything and cannot find a common earth. Is the horn really meant to only have a positive feed? No discernable earth? This has wasted so much of my time already, it would be easy to make the int light work but it doesnt really solve anything, especially come MOT time. Doesnt help that the loom has been butchered by previous owners either. Got home today to find the NS front spring has collapsed. Oh joy. Thanks again.

[Timbob]

I require the opinion of someone smarter than me please. I applied a 12V feed to the wire on the interior light switch, I now have a functioning interior light; if I press the horn button?! The ohmmeter shows no tangiable earth at the interior light itself, but one at the switch. Should I remake an earth at the light itself?
Please advise, I am most confused

[AbyssDJ]

heheheh... i know this one ;) its a fuse... but which one is the fun part. i had exactly the same problem a week ago, and it took ages to suss it out. follow the wiring for any purple cable in the wiring diagram, and check ALL the fuses that they connect to.

the wiring on the purple (ie. constant 12v) is really wierd in some bits..... why the hell they did it the way they did i dont know.

[Timbob]

Thankyou muchly. I assumed the only fuse involved was that one serving the circuit. Not myriad others. I assume there are fuses other than those behind the fuse cover?