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Horn Fuse
Posted: Sat Jun 07, 2008 12:48 pm
by Newtothefourbeworld
Gday guys i could use a hand.
Noticed that my drivers side rear indicator wasnt working so i went on a fuse hunt and found the horn fuse blown. I went to put a new one in and it sparked and blew straight up (the car was off too). with a multimeter attatched i went in search of the probelm but came up with nothing. I disconected the horn button, and then the horns but no change. Anyone know what else is o that circuit that i can check? thanks
Posted: Mon Jun 09, 2008 6:46 pm
by Newtothefourbeworld
sooooooooooooo, no ideas then hey
?
Posted: Mon Jun 09, 2008 10:04 pm
by MightyMouse
And the model is...... ?
Posted: Tue Jun 10, 2008 8:54 am
by Newtothefourbeworld
ah didnt think it would really matter but its a 94 F310. Just not sure what to check or what could be causing the problem. It needs to be a short on constant power as the multi meter should 12.8V going across the fuse all the time but im not sure what on that circuit would have constant power.
Posted: Tue Jun 10, 2008 9:35 am
by Gwagensteve
The Horn is constantly powered in most cars.
Steve.
Posted: Tue Jun 10, 2008 2:59 pm
by MightyMouse
Powered from battery via main fuse, Horn Hazard Fuse.
Permanently "hot", earthed to ground through horn button on steering column.
My bet - short to ground in one of the horns.
Pull the + wires off the horns - no fault then replace one at a time...
Of course could be a wiring issue..... F300 Manual BE page 33
You have downloaded the manual from
www.warfs.org haven't you ?
Posted: Fri Jun 13, 2008 10:27 am
by Newtothefourbeworld
ok so you bet MM is to pull the -ve of each of the horns in the front bumper, replace the fuse and if it doesnt blow replace each at a time and see which one blows it?
yeh i have the manual but couldnt find a wiring diagram but i will check out those pages! thanks
Posted: Fri Jun 13, 2008 12:35 pm
by MightyMouse
Yep - at least that will indicate if its a failed horn ( there's two ) or wiring from the battery.
If it was wiring FROM the horns then they would be on all the time and you would notice it

Posted: Fri Jun 13, 2008 4:34 pm
by Newtothefourbeworld
well i dunno as i cant get a fuse to survive long enough to complete the circuit.
Another weird thing i figured out today was that hazards work when high beam are on..................
Posted: Fri Jun 13, 2008 6:37 pm
by murcod
Possibly your hazards are shorted to the high beam circuit?

High beam would draw enough current to blow the fuse I'd imagine?
Try unplugging the headlight bulbs on each side and see if the fuse still blows? Strange but it's worth a try!
Posted: Sat Jun 14, 2008 12:32 pm
by Newtothefourbeworld
ok this is driving me insane!!!!!!!
Here is a small list of facts and bear in mind the horn/hazzard fuse is not in place while any of these tests were done:
- Constant 12V power across fuse blowing it instantaneously
- Turn car on and it jumps to 14.3V
- Turn High Beams on and drops to 0.5V, hazards work, and wehn i turn the spotties on (whihc are wired throuhg highbeam) and then off again they cause a spike in volts. Also while the hazards are on the drivers side rear indicator + all the passanger side works but not the front/side indicator whihc is the opposite to when i use the right indicator on its own (ie not throuhg the hazards)
- Diconnecting the horns did nothing
- Disconnecting the headlights did nothing
Im going insane trying to figure this out and i know i will get booked eventually for my indicator not working and also know that the horn doesnt work i always need to use it for stupid people on the roads.......evil murphy!
Posted: Sat Jun 14, 2008 2:38 pm
by murcod
Check all your wiring looms for wear (something might have worn through the insulation and be shorting to the chassis.) Look in the engine bay and under your dash.
Check all additional wiring that has been added- usually it's the add on bits done DIY that cause failures.