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Anyway, removed Wolo horn, installed OEM (Drag Specialties) horn. Removed the horn relay that the Wolo required. New horn wont sound. Hooked direct to battery and it works fine. Green wire from horn switch, connects power from ACC CB to horn. Black wire from horn routes up to connect with Fuel Sender (fuel sender works fine) and on to ground with the Stop Light Relay. Circuit test results: 1) Continuity good in GND 2) horn wires test OL then good continuity when hone sw engaged 3) heres the weird one testing horn wires for DC voltage, Ig switch ON, voltage starts slowly climbing way past 50 a BS number but when I engage horn switch DC volts immediately go to battery voltage BUT, the horn wont sound
Something must have happened to stop the Wolo from sounding, as the horn relay tested good. Im thinking the original wires from horn switch may have a split somewhere and rewiring will fix.
what would cause the weird voltage reading in 3) above?
The only accurate way to read voltage in a circuit is when the component is under load.
Connect the wires to the horn, then read the voltage at the green wire with the button pressed, what is it?
Make sure the meter is reading DC volts...
Hi Dan, been awhile. I boned-up on the Voltage Drop procedure and found the horn circuit has 9V drop. Verified that by probing at the horn under load and got 3.2 volts. No wonder the darn thing wouldnt sound. Actually made a video of it since it really illustrates the condition and procedure. Im sure guys will pick it apart here and there but here it is
Now go to the connector for the left-hand switches.
Unplug the connector, clean and inspect for damage or corrosion, make sure no sockets or pins are pushed out of the connector halves, connect the connector halves back together.
After good spray and blow on connectors 1, 3 and horn switch, Im getting 5.6V to horn vs. 3.2V. V drops and gross voltages are:
Horn switch 0.6V drop (black vs orange at #1 connector) however, total volts at each are 7.7 and 7.1
Horn switch from battery V drop 5.0 orange, 5.6 black
Heres the two biggies: Connector 3, green wire to horn, V drop off charts and connector 1 to 3, beige/black V drop off charts
Btw, new V drop from battery to horn is 6.7 vs the 9 before cleaning.
Guess Im looking at swapping a couple wires between connector 1 thru 3 and to the horn (at a minimum)
Those jumper wires you’re using are next to worthless. They are too small and typically have very poor connections to the clips. Try direct readings with the voltmeter leads and ditching those jumpers.
Answer Dans questions and you’ll be closer to resolving the issue. Don’t make it so complicated.
Hey all going to terminate this thread. Ive done more load drop tests than I want to type and people want to read. I’ve ID’d major culprits and are replacing several 34 year old wires, terminals and some Namz with Deutsch connectors. Good winter project, and I’ll have a freshened up power delivery and accessory system, etc. just as I fixed the start/charging system when I put in the new S&S 111. All good (double starter relay setup is kicking a$$ still)
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Weird Voltage Reading
