Horn not working no power at fuse box

-
G

Greg S THomas

Active Member
Joined
Jun 12, 2016
Messages
40
Reaction score
4
Location
Minnesota
I have a 1973 Dart Sport and can't get the horn to work. I tested the horn with a wire to the battery and it works. I checked the horn wire on the steering wheel and there is no power there. I then traced the steering wheel horn wire back to the fuse box and there is also no power at the fuse box for the horn. Can someone tell my why there wouldn't be any power at the fuse box for the horn.

Also, does anyone know where to find a chart of what the fuse in the box are for?

Thanks
 
I don't know, but maybe the steering wheel wire provides a ground, not voltage? This ground could go to a control relay which switches 12vdc from bat to horn. If you have a dedicated fuse with no juice on either side, would have to trace back the wiring to source. If you can't see it a schematic would be good, good luck.
 
A voltmeter, which draws very very little current, should show voltage at the horn button when the thing is not grounded. This of course is measuring "through" the relay coil from battery source
 
If you traced the black wire from horn switch in column all the way back to the fuse box, the ground side of this circuit is fused. I knew this was the method in earlier models. My 67 carries her horn relay and horns right out in front of the alternator and gets power directly from alternator.
The black wire ( ground signal to relay coil ) goes into cab through fuse box and on to the column.
I assumed they had changed this in later models such as yours but... maybe not.
Anyway... look for 12 V at other terminals of horn relay. If you find it, that relay could be the culprit.
 
Way different, Red, in 73. Horn relay is up under the dash "left side cowl" and the supply runs direct from the fuse panel. The horn relay has 4 pins, a separate connector for the key buzzer. The horn fuse supplies horn and park/ tail / dash lamps

OP: If you have not done so you need to get a service manual. You can download 'em free from MyMopar. Several of them there for download, came from the guys on here, including the 73 manual
 
Thanks for all of the replies.

I down loaded the shop manual and found the part on diagnosing the horn not working.

I went thru the steps and got down to putting a jumper between the horn relay sockets 1 (to fuse) & 3 (to horn) and the horn sounds! The next step is to put the jumper between sockets 1 (to fuse) and 2 (to horn switch) and depress the horn button. When I depress the horn button I get lots of sparks at the horn button (not good) and no horn. I removed the wire from the horn button and touched it to the metal on the steering wheel and again lots of sparks. The final diagnosis from the manual is 'Faulty horn button Switch connections or wiring'.

So with the sparking going on does anyone have a answer on how to fix my problem? I think I eliminated the faulty horn button by removing the wire from the horn button and touching it to the steering wheel.

Thanks
 
Some arcing is normal for that black wire contacting a ground.
 
I think what you have is a big problem in the relay. The sparking at the button should be very minor, (subjective) but ALSO should cause the relay to click, which you can hear, and or the horn to operate.
 
The sparking at the steering wheel is what I would consider excessive - it actually left a couple of marks on the metal. According to the shop manual its not the horn relay its a 'Faulty horn button switch connections or wiring'.
 
When you jumpered the relay terminals 1--3, you BYPASSED the relay. This shows that the battery power to the relay connector is good, and that the wiring to the horn and that the horn itself is good


WAIT A DAMN MINUTE................You jumpered WHAT to the switch? (Post above?)

"The next step is to put the jumper between sockets 1 (to fuse) and 2 (to horn switch) and depress the horn button."

THAT IS NOT WHAT IT SAYS!!!!

Page 8-81 of the 1973 service manual


Horns Will Not Sound
Should the horns fail to sound, substitute a known-
good relay in the circuit and depress the horn switch.
Should the horns sound, the relay is defective and
must be replaced. If the horns do not sound, discon-
nect wire connector at horn and connect one lead of
test light to the connector and the other lead to a good
body ground. Depress the horn switch. Should the
light illuminate, the horn is faulty and should be ad-
justed or replaced.
If the light fails to illuminate, unplug the horn relay
and connect the test light to terminal "1" on the relay
terminal board and the other lead to a good body
ground. If the light fails to illuminate, inspect for

corroded battery terminals, dead battery or an open
circuit in the wire from the starter relay to terminal
"1" of the horn relay.
Should the light illuminate, touch a jumper wire
from relay board terminal "2" to a good body ground.
Sounding of horns will indicate a defective horn
switch or an open wire from relay board terminal "2"
to the horn switch.
CAUTION: Continuous sounding of horns will cause
relay to fail.
Horns Sound Continuously
Should the horns sound continuously, unplug the
horn relay from the terminal board inside the passen-
ger compartment. Plug in a known-good relay. If the
horns stop blowing, relay is defective and must be
replaced. Should the horns still sound, proceed as
follows: Connect one lead of test light to terminal "1"
on the relay plug-in board and the other lead to termi-
nal "2." Should the light illuminate, either the wire is
shorted to ground or the horn switch is defective.
Remove steering wheel trim and disconnect wire
from horn switch. Repeat the above test and if the
test light still illuminates, wire is shorted and should
be repaired. If the light does not illuminate, horn
switch is defective and must be replaced.

Don't take that flow chart too literally. What you are doing with the switch is you are grounding the coil of the relay, the other end of which has power. That should activate the relay. If the relay has an internal short or other problem, I can see how the horn wire to the switch might be doing that. I'm tellin you. From what you are describing, you have a bad relay. TAKE THE RELAY OUT OF THE CAR and pry the tabs off the top and take the thing apart.

horn.jpg


hornc.jpg
 
Last edited:
Odd that the detail instructions are not the same as the flow chart. So I followed the instructions from 8-81 but I can't do the first thing they say to 'replace the Horn Relay with a know good relay' because I don't have another relay handy and none of the parts stores carry one. I moved on and connected a light from terminal 1 on the relay board and the light does light. The next step is to touch a jumper wire from the relay board terminal 2 to a ground and the horn does not sound and there are no further instructions on what do do if the horn does not sound.
I did take the horn relay out and it 'looks' fine, no corrosion or any broken wires that are visible.
One other thing, when I get the sparks at the horn switch the Horn Relay in unpluged.
Thanks for any more ideas.
 
Greg S THomas said:
One other thing, when I get the sparks at the horn switch the Horn Relay in unpluged.
Thanks for any more ideas.
Click to expand...

ARE YOU SURE you have the horn button wire? With the relay out, the wire should be "open." So either you unplugged the wrong component, or the wiring is crossed up in the harness.

With the relay "unplugged" measure voltage at the horn wire It should be "cold." It should have infinity (open) to ground. The horn button wire only goes one place......from the horn button to the relay.
 
I am positive I have the horn wire/horn relay switch. When I jump between sockets 1 & 3 (per the flow chart) the horn sounds so I have to have the right wires.
So are you saying that the wire from the horn switch is shorted out or crossed up in the harness between the horn switch and the horn relay?
 
The horn button wire only goes one place. From the horn button to the relay socket. There is NOTHING else connected. When you unplug the relay that leaves that wire completely open. So, I already said.....above......

"With the relay out, the wire should be "open." So either you unplugged the wrong component, or the wiring is crossed up in the harness."
 
I was able to find another horn relay to test with and sure enough the horn worked.

Thanks for everyone's help.
 
You must log in or register to reply here.
-

Back
Top