car electrics help plz

[Wideboy]

Problem: every time i press the button to switch on my rear window heater it blows the fuse

Things done:
i've ripped the dash out, inspected the button = fine.
wire's going into the tail gate from the roof = fine, as far as i can see.
disconnected the wires from the window to break the circuit = still blows.

all this has resulted in a lot of blown fuse's and very pished off me!

the fuse is shared with the horn but the horn doesn't blow the fuse.

tomorrow I'm going to check the relays but is there anything else??

relays are prob the way to go, rear window heaters use lots of power and the fuse will pop to stop the wiring getting hot.

[Biker Biggles]

But not with the heater element disconnected?My vote is for a problem in the switch,or a chafed wire earthing out in the live feed to the rear window.

[Ruffy]

Try disconnecting the feed from the relay to the window heater element at the relay end, checking that the relay still clicks when the switch is operated (check for 12V at the output connection of the relay.) If this blows the fuse then the problem is probably the switch or relay, otherwise the wiring from relay to the heater element.

You can also disconnect the switch feed at the relay to isolate that section of the circuit to check if that's the problem.

[Richie]

stick a nail in the fuse holder......































no please don't.

[Wideboy]

the relay still clicks after the fuse has blown is this normal? (i know jack about electrics)

Originally Posted by Richie

stick a nail in the fuse holder......

no please don't.

don't tempt me, luckily i got the haynes out otherwise i would be royally in the s***

failing this i will be pushing the bloomin thing off a cliff

[Ruffy]

Originally Posted by Wideboy

the relay still clicks after the fuse has blown is this normal? (i know jack about electrics)
...

It can be normal. A relay is basically a remote control switch: The switch you use in the car operates the relay, then the relay operates the heater circuit. If the power to the switch on the dash is fed from a different fuse than the heater circuit then the relay will still work but no power will get to the heater.

This probably means there's a fault in the heater wiring somewhere (probably insulation rubbed off on a panel edge/hole) or the fuse is too low a rating (what rating is fitted - has it just started blowing recently? BTW, what type of car is it?)

[Wideboy]

no it just randomly went on Saturday night, the light in the button dont light up anymore when you press it

[tigersaw]

got a meter? Can you measure resistance from the wire you pulled off the heater element (live feed) to chassis - when heater not turned on/ fuse out - should be high or infinite, low reading suggests cable damage or fault.
If its french then I suggest you give up now.

[Richie]

Originally Posted by tigersaw

If its french then I suggest you give up now.

yarp...