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Trying to sort out all of the electrical gremlins in my car (68 442) and I've reached the horn. I'd like to test if the button itself is functioning correctly.
Can anyone recommend a way to test it at the harness connector using a volt meter?
I'm not sure exactly how it is supposed to function and I should mention that I have no idea its put together right. So far I have popped the button off and removed the three screws that hold the piece the button clips onto. I am down to a spring loaded post inside the top of the column, I notice the piece attached with three screws has what I assume is a corresponding piece that sticks out and makes contact with the post.
Please enlighten me, no horns = no inspection = parked!
Sorry, would have been worth mentioning wouldn't it: I did try to get power at the relay, but could not. Ive been under the dash lately as I am finishing up a dash harness swap, so the connector is handy.
Unfortunately, the previous owner loved to cut wires and spliced with lots of random colors, so figuring things has been tough. Also, the forward harnesses seem to have come from whatever car the engine came from, (71 455?) and not the car. Both forward harnesses have multiple splices and are both rats nests, but I can't afford to replace at the moment.
Sorry, still new to electrical and getting my terminologies straight, what I did is ran the horn wire at the relay through a volt meter to ground and tested for continuity while pressing the horn button, and got nothing.
At this stage I was just hoping to establish that the button mechanism is good.
This is all complicated by the fact that the relay is bad (tested and could not get it to click, got the key buzz though), and there is only one horn in the car.
Last edited by rothlane'68; October 22nd, 2016 at 04:45 PM.
If you ohm out the wire from the horn button to the horn relay, you should have continuity. Or, you can put a volt meter on the wire with it disconnected at the button and connected to the relay, you should see 12v provided through a good relay coil. It does not matter that there is only 1 horn as long as it works. You can jumper 12v to it to test.
Let's back up. First, I ASSUME you have a three spoke or four spoke sport wheel with the circular horn contact, correct?
Next, when you say you tested the "horn wire" at the relay, which one? The black wire comes from the horn button and provides ground when the button is pressed. The green one runs to the horns and gets 12V on it when the relay is energized.
Let's start the easy way. Disconnect the black wire from the relay. Connect a jumper from that terminal on the relay to ground. Does the horn work? If so, everything from there out is working. If not, disconnect the green wire from the relay and jumper this green wire to 12V. The horns should blow.
Ok, got the horn to blow by connecting it straight to the battery.
So, based on the previous tests, there is a fault in the harness. As I noted before, I am fairly certain that the relay is bad as well, so it looks like I have some parts to buy!
Going back to the original question though, and so I can order all my parts at once: is there any way to test the contacts inside the steering column?
Yes, put it all back together and disconnect the plug on the horn relay. Hook an ohm meter to ground and the black wire going to the horn relay and have an assistant push on the horn. You should see continuity when the horn button is pushed.
Yes, put it all back together and disconnect the plug on the horn relay. Hook an ohm meter to ground and the black wire going to the horn relay and have an assistant push on the horn. You should see continuity when the horn button is pushed.
The problem is that a low impedance VOM will show continuity for even a marginal connection. A better test is to use a test light, which will simulate a load on the circuit. Since the horn button provides ground, the test light needs to have one end connected to +12V and the other to the connector on the black wire that goes to the horn relay.
Yes, put it all back together and disconnect the plug on the horn relay. Hook an ohm meter to ground and the black wire going to the horn relay and have an assistant push on the horn. You should see continuity when the horn button is pushed.
Tried the above and got nothing! Did not have a test light so could not try Joe's method, not sure if I could be missing something else, you guys seem to imply that one of these contacts going bad is fairly rare. Everything else on the column works, hazards, turn signals come on and cancel correctly...
Could I be missing something. Anything else could I try before breaking into the column?
Is there an existing thread on disassembling the column/horn contact you can point me toward?
Could I be missing something. Anything else could I try before breaking into the column?
Is there an existing thread on disassembling the column/horn contact you can point me toward?
Pretty much everybody assembles the horn contact and pin incorrectly the first time. Of course, there is a diagram in the CSM, and about a hundred threads about it here.
Spring in the hole FIRST, then the eyelet (big end down), then the plastic retainer.
I'll check for sure tomorrow, but the contact seems to be installed correctly...
From the research I've done, it looks like the contact (the one were talking about) plugs into the cancel cam which in turn makes contact with another spring loaded contact that is part of the turn signal cam?
Whats the most likely point of failure in the mechanism? Have you run into this before?
The turn signal switch has a spring loaded contact, as shown at about 12:00 on this photo.
The cancel cam has a conductive ring that rides on this terminal.
The spring, eyelet, and retainer go into the post on the cancel cam and make contact with the ring. The contact ring screws over this and the little "L" shaped leg on the contact ring touches the eyelet.
There are a LOT of possible failure modes in this system. The horn contact grounds the black wire in the harness, which is connected to the terminal in the switch, which is connected to the eyelet in the cancel cam, etc, etc. The OTHER side of that ground circuit comes from the steering shaft. Note that the steering shaft is bolted to the non-conductive rag joint at the steering box. There is normally either a jumper wire or metal strap as part of the rag joint to assure conductivity to ground for the horn. If that wire or strap is missing, guess what? If any of the spring loaded contacts aren't touching, guess what? If the black wire in the column harness is broken or not connected, guess what?
You need to understand all the parts of this circuit and test each joint from chassis ground to the terminal on the relay to find the problem.
... disconnect the plug on the horn relay.
Hook an ohm meter to ground and the black wire going to the horn relay and have an assistant push on the horn.
You should see continuity when the horn button is pushed.
Originally Posted by rothlane'68
Tried the above and got nothing!
That's because the above is incorrect.
You disconnect the plug with the green wire and the black wire from the horn relay,
then you place one lead of the volt meter or test light (test light preferred) into the plug to connect with the black wire and connect the other lead of the meter or light to the (+) terminal of the horn relay or the battery -
When your accomplice presses the horn button, the meter should read 12V or the light should light.
Do this before messing with the steering column.
As an aside, you should have a test light.
Just take an 1157 bulb and solder a wire to the side and another wire to the button on the bottom.
Now you've got a test light.
Alligator clips optional.
No, actually it isn't. The horn button grounds the black wire. If you pull the black wire off the horn relay and connect a ohmmeter between the black wire and ground, you SHOULD see continuity (ie, 0 ohms) when the horn button is pressed, open circuit (ie, infinite ohms) when it is not.
No, actually it isn't. The horn button grounds the black wire. If you pull the black wire off the horn relay and connect a ohmmeter between the black wire and ground, you SHOULD see continuity (ie, 0 ohms) when the horn button is pressed, open circuit (ie, infinite ohms) when it is not.
Ah.
Yes.
He said "Ohmmeter."
I saw talk of test lights, etc., and my brain skipped right over and read "voltmeter."
Either way, I would submit that an ohmmeter (especially the new auto-ranging digital ones) pushing 2 or 3 volts can be a fickle beast, especially in the hands of the inexperienced, while a test light or a voltmeter measuring a higher potential dsifference is more likely to give a clear reading, and one that I would have confidence in.
Either way, I would submit that an ohmmeter (especially the new auto-ranging digital ones) can be a fickle beast, especially in the hands of the inexperienced, while a test light or a voltmeter is more likely to give a clear reading, and one that I would have confidence in.
Kinda what I said back in post #13, where I also pointed out that the test light needed to be connected to power, not ground, for that test.
Kinda what I said back in post #13, where I also pointed out that the test light needed to be connected to power, not ground, for that test.
Quite so.
I'm just not completely sure that this guy has really done enough checking to justify taking things apart, and I was trying to re-read what's gone on already to find what may have been missed, while being distracted at work, which is admittedly a suboptimal condition.
I'm just not completely sure that this guy has really done enough checking to justify taking things apart, and I was trying to re-read what's gone on already to find what may have been missed, while being distracted at work, which is admittedly a suboptimal condition.
What tool do you guys recommend to pull the steering wheel?
A steering wheel puller?
You will also need a lock plate spring compressor to get the snap ring off and on again.
Before going to all this trouble, you DID verify continuity (or lack) from the connector at the base of the steering column to the terminal inside the cancel cam, right?
Ahh... yes... its in the name isn't it. The picture helps though, after looking at my column, I see how it works. I've heard that there is a hammer method but that its not advisable.
Originally Posted by joe_padavano
Before going to all this trouble, you DID verify continuity (or lack) from the connector at the base of the steering column to the terminal inside the cancel cam, right?
This was literally the first thing I tried, just before starting the thread.
I'll list off what I've done to test everything and maybe you can let me know if we've missed something:
-tested the relay: clicks no, buzzer yes
-tested for continuity between the horn contact and steering column connector (no continuity)
-tested for continuity from the steering column connector through the harness to the black wire on the relay (positive continuity)
-tested for continuity from the green wire to the horns and touched it to the positive terminal on the battery (no continuity and horns do not blow)
-connected horn to battery (horn blows)
-connected black wire with test light to positive terminal and pressed horn button (light does not come on)
-connected black wire through voltmeter to negative terminal and pressed horn button (open circuit)
-tested that the column is grounded (it is)
-horn contact installed correctly: looks right (big end down), but I didn't install it.
Conclusions: relay is bad, front light harness (green wire) is compromised, horns themselves (just the one of them) is good, horn contacts inside the column are likely bad.
I don't like the idea of taking the column apart. I may table the whole thing until I've replaced the relay and repaired or replaced the front wiring harness so that I am working with a smaller pool of variables.
Got antsy, pulled the steering wheel. Found a few things that don't seem right:
-Cancel cam looks like the wrong type, contact is incorporated, OPGI website says its a non tilt type, this is a tilt wheel.
-Got continuity through the cancel cam and turn signal switch through the harness, but not both together.
-Turn signal switch contact is gummed up and sticks.
-Turn signal switch is cracked through by the lever and wired back together in a beautiful piece of redneck engineering!
pictures attached
I assume the problem is either the incorrect cancel cam, the sticking/cracked switch, or both. What do you guys think?
Are tilt/non tilt switches interchangeable for 1968? Some vendors seem to suggest they are not...
October 22nd, 2016, 02:18 PM
Horn troubleshooting
how could you tell? 
