gcthree

I know that I'm missing something really obvious here, but I've checked a few items on my inoperative horns, and it all checks-out...but no horns.

I have an aftermarket MOMO wheel and their horn button. It works perfectly and closes the circuit when I test for continuity.

I have 12 volts at the 2 wires fitted to the horn button.

When I press the button, I get 12 volts at the wires affixed to the horns.

I've applied 12 volts to the horns and they both work.

But they will not blow. What am I missing?? I'm stumped....

Bob

the flyin' scotsman

IIRC the horn button completes the ground circuit......if you have 12v at the horn check for ground.

Mrmerlin

test the other way ,
go from the tab on the TS switch to the steering shaft,
if you have a horn then put on the steering wheel,
make sure to adjust the TS switch so the tab is just making contact with the horn ring,
view the switch height from under the column.
then touch the wire to the steering shaft if good then test the horn button metal spring to shaft.
NOTE If the upper column bearing is loose it can cause the ground to be broken.

NOTE if the button has 2 wires then they must be wired correctly. this may be your issue

gcthree

Thanks Stan / Malcolm. Good check list. I'm on it....

dr bob

I started with the ohm meter plugged into the relay socket. Worked backwards through the horn button side to verify that I had continuity to ground at the 31 socket terminal when the button is pressed. Going the other way, I could verify that I could toot the horns from the relay socket with a jumper from 30 to 87. You need to show 12V at 30 in the socket, as well as at the 86 terminal in the socket. referenced to ground.

gcthree

Really helpful. Never thought about the relay.

Again, my 'stumped' comment was based on seeing 12V at my meter attached to the horn connections. If I have 12V there, why will a pair of working horns not blow? Overlooked the ability to jump at the relay and test them.

Thanks!

Alan

I'll bet you don't have 12v there when the horn is actually connected... The horn is a high current device - if you have poor circuit connectivity (resistance in the wiring/connectors) - then the voltage will be dropped over that and the horn will see only a tiny voltage. Test it with horn in circuit - if you can - slide the rubber boots up the wires OR just add short jumpers - work backwards monitoring connections until you find the one where the voltage does not droop - clean after that...

Alan

gcthree

Jumped the relay and got my horns. Worked back to the wheel to find that, per Alan, a corroded ground wire inside the hub. New wire = horn blows.

Thanks everyone.

Bob

James Bailey

Alan is very, very good with the electrical !!

chitown928s4

Great job...sometimes the little things give the greatest pleasure.

gcthree

Yes they do!

Solved the horn issue, and an uncooperative tail lamp socket one, too. Poured a gallon of windshield fluid into the tank to silence the messaging on the e-dash, and watched most of it leak out the bottom past a seal with tiny rip in it. Hello Roger! Win one....lose one!

Mrmerlin

Glad your back to being horny,
So while your messing with the washer tank,
remove the fill tube and tank inlet metal collars,
this will keep the tank free from corrosion,
But so will an empty tank

the flyin' scotsman

Good to know Bob......grounds are a crucial component of the 928 electrical system.....emphasis on the plurarl