Horn Problems
 

New one today - wife drove her X5 home and parked in the garage. After roughly 5 minutes the horn starts blow and she can't get it to quit until roughly 25 minutes later when the fuse blew.

I replaced the fuse several times and as soon as I hit the horn button on the steering wheel (airbag) the fuse blows with just a whimper from the actual horn. Without the fuse in place I can hear the relay activating but only when pressing on one corner of the steering wheel button which also seems odd.

I have searched and found that the e46s had issues with the horn button but didn't see anything related to our X5s.

I am guessing something to do with the steering wheel button. Not sure if simply taking the airbag off and inspecting the horn contacts would reveal anything obvious but that may be the place to start.

Anyone have experience with this issue or advice?

Thanks in advance
DJ

2008 X5 3.0si
110K miles

id look at a schematic first....
if the fuse is blowing it is too much current. What causes too much current to be pulled? NOT a 'contact'.

You might have had a contact or relay issue, which resulted in the horn driver overheating, melting and now being internally shorted.

Just a WAG.

Never heard of this issue.

Schematic, ohmmeter, calculator....

I agree with ard. The steering wheel contact is not why the fuse is opening at this point. Either:

(1) The contact in the steering wheel closed for some reason which picked up the horn relay and energized the horn. Then, after the horn sounded for an extended period of time, the horn failed internally, shorting the circuit and causing the fuse to open, or

(2) A contact in the horn relay was closed for some reason which energized the horn. Then, after the horn sounded for an extended period of time, the horn failed internally, shorting the circuit and causing the fuse to open, or

(3) A fault in the horn power supply wiring initially caused the horn to sound for an extended period of time which caused it to fail internally and cause the fuse to open. The damage to the horn and/or the power supply wiring fault continues to cause the horn malfunction and opening of the fuse, or

(4) A fault in the horn control wiring could be be causing or contributing to this mal-operation.

As you are experiencing poor function of the horn now, there is little doubt in my mind that it is damaged and is causing the fuse to open. That is only half of your problem, though.

The fuse is supposed to protect the load; in this case, the horn, and will only open if the load is drawing too much current. The horn is an intermittent type load and itself not designed for extended operation.

Thanks for the reply. I will check the horns out tomorrow to see if I can determine if one or both are bad which at this point would make sense and then I will go from there. It is still a mystery as to why the horn self activated though but I think you guys are right at this point I should isolate why the fuse is blowing.

Sent from my SM-N900T using Tapatalk

OK pulled the horns this morning. Tried to bench test applying direct current to one of the pins on the horn and ground to the other pin to see if either horn would operate. Neither one did so I am assuming that both the high and low pitch horns are toast at this point.

Also attempted to check the voltage at the fuses with the horns removed. I got a full 12 volts at the 15 amp fuse in the passenger floorboard when the horn switch at the steering wheel was activated with the ignition on. No voltage otherwise.

With these tests would it be safe to say at this point that I need to replace both horns and monitor the steering wheel horn switch to ensure that it continues to work properly?

How many ohms do you get for each horn?

V=IR.

If the ohms are low, then it is pulling too much current and that is blowing the fuse-

I dont know the schematic- is there a relay off the steering switch that then powers the fuse to the horn?

If there is a cheap horn relay, you might replace that as well. A stuck relay might be much more likely than a stuck switch contact.....

Quick additional tests this morning. Confirmed that with the horns activated at the steering wheel I get the full 12 volts power at the connectors for each horn.

Therefore at this point I have ordered new horns.

Will install the new horns and hopefully the steering wheel horn switch wont activate or get stuck on its own again. If it does, I know which fuse to pull (wife does to as she is the one that drives it the most).

Thanks for your help guys - I will hopefully confirm that the new horns resolved the issue next weekend.