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Wiring problems

navi

Full Member
Joined
Jul 17, 2020
Messages
155
There's something going on with my electrical connections. In the last couple days the speedometer needle is out, same with the horn. And the stereo goes off and on with bumpy roads.
Could this be a loose ground, is there a guide for checking the many ground locations?
Thanks
 

ngsd

Contributor
Bronco Guru
Joined
Mar 2, 2019
Messages
2,096
Speedometer is mechanical unless you have digital gauges.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
43,567
Need some more information.
Such as, what year is your Bronco and what all has been done to it that could effect these things you're experiencing?

...is out, same with the horn.

What do you mean by "out" in the case of the horn? Does it not work at all?

And the stereo goes off and on with bumpy roads.

Is it a factory radio? Guessing not since you said "stereo" and Broncos never came with one of those.

Could this be a loose ground, is there a guide for checking the many ground locations?

It can always be a ground, but we don't know until we know more about your setup.
There really are not that many grounds on a Bronco. Some are done with ground wires, some with the component mounted to the body. Usually adding more is not a bad thing, but making sure that your Bronco has at least the existing ones clean and tight and in good general condition goes a long way.
Speaking of which, what is the condition of your wiring system overall?

And if you haven't already, remove all of your fuses, clean them up, clean the contacts in the fuse panel, then put the fuses back in. This should not fix your issues, but it's a good practice with old rigs and glass fuses if it has not been done in awhile.

Paul
 
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OP
N

navi

Full Member
Joined
Jul 17, 2020
Messages
155
Need some more information.
Such as, what year is your Bronco and what all has been done to it that could effect these things you're experiencing?
Thanks for the help.
It is a 73, stock engine, tranny, dash, wiring. It looks like the wiring has been redone maybe 20 years ago based on the vehicle history.
The stereo was fine until I drove on a rough road and rattled the hell out of everything. I put the tire pressure (33") back down to 35 to soften the ride.

What do you mean by "out" in the case of the horn? Does it not work at all?
When I press the horn button there is a clicking noise from the horn but that's it. Oddly there are two horn speakers under the hood, both wired.

Is it a factory radio? Guessing not since you said "stereo" and Broncos never came with one of those.
No, it is a recently installed, new stereo


Speaking of which, what is the condition of your wiring system overall?

The wires don't look in bad shape, connections are tight,
it looks a bit disorganized, hard to follow where everything goes.
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,830
Grounds,
Negative battery post to the engine block behind the alternator.
negative post to the body inner fender behind the battery.
starter solenoid to the fender well grounded by its mounting bolts.
Voltage regulator by its mounting bolts to the firewall or inner fender depending on when your bronco was made.
intake manifold to the fire wall.
rear taillights ground to the frame at the rear driver side frame by the bumper.
Dash grounds to the body mounting bolts and gauge grounds to the dash by its mounting bolts.

If this was my Bronco I would run a ground from the gauge cluster mounting to the body tub. and I would add a ground to the frame from the engine ground connection

as for horn depends on whether your hazard flasher is on the dash or the column. they both switch to ground through the steering column. the early sought ground through the steering shaft down through the steering box trouble starts here if some one replaces the steering coupler. factory steering couplers had continuity through the rubber doughnut in the later models. after market stuff doesnt always do that so you have to provide a jumper there. early dash mounted flashers had the horn direct to operation. Later Broncos with the flasher on the column used a relay for the horn mounted on the front fender well on the passengers side. ground went up through the steering column doughnut went through the horn switch down the column to the horn relay. the mounting bolt is ground for the relay so it must be a clean mounting. it is a very odd relay being a 3 tab relay. horn switch operated the relay and the relay sent power to the horn. horns themselves were grounded by their mounting bolts.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
43,567
It is a 73, stock engine, tranny, dash, wiring. It looks like the wiring has been redone maybe 20 years ago based on the vehicle history.
The wires don't look in bad shape, connections are tight, it looks a bit disorganized, hard to follow where everything goes.

What makes you think it was redone? Records showing a rebuild or something like that? Are they still factory colors? Maybe they were just gone through and fixed a few flaws, rather than replacing.

When I press the horn button there is a clicking noise from the horn but that's it. Oddly there are two horn speakers under the hood, both wired.

Not too odd, since even though yours is before Ford offered them (first time in '76 I think?) a lot of people would add another horn so that we could play with the grownups back then. Most vehicles of the era had two horns, while Broncos got one relatively anemic one.
So having two is a good thing, but it wears out the horn contacts under the steering wheel much quicker.

Your '73 most likely does NOT have a horn relay, so the clicking you're hearing is either the horns have worn out/rusted inside, the horn button contacts need renewing, the ground at the horn itself is not sufficient, or something else is keeping the full current from making it to the horns.

Easiest way to verify the first half of that is to run a jumper wire straight to each horn wire. With the horn still bolted to the body, a jumper wire will make a good horn honk very easily.
Check to see if you have one or two wires. Factory horns were single wire and the ground was through the mounting bolt. If your Bronco has been re-painted and/or is a bit rusty, you might not be getting a good ground to the horn.

If they honk, you can then move up the chain of command and find out what else is causing the problem.
With the old system the full current to the horn passed up into the column on one wire, then through the copper/brass/whatevertheyremadeof contacts and then down another wire to the horns. All that current flow, especially doubled with two horns, wears out the contacts. You can sand them smooth of carbon buildup, grease them up with dielectric grease and they may be good for a few months to a few years, but the best way to get the horns to work better and the button to last longer is to install a horn relay.

The stereo was fine until I drove on a rough road and rattled the hell out of everything.
No, it is a recently installed, new stereo

Well there's your problem right there. And only you'll be able to find out what came loose, or which fuse blew.
A new aftermarket radio might have it's own inline fuses, and might no longer use the one in the fuse panel. But you might as well check all the fuses anyway, just to rule it out.
As with any vehicle this age using glass fuses, remove them all, clean them, then put them back in. Gives the electricity a fighting chance of making it through the system unmolested.
Then just go on the hunt for loose, or broken wires which only you will be able to find. Could be as simple as reaching under and moving wires around until it works. Or it could be the way you spend the next few days of your life on your back with your neck twisted into an "S" shape under the dash!%)

I put the tire pressure (33") back down to 35 to soften the ride.

Wow! Down to 35? What were you running before?
Most of us are down in the 25-30 range at the most. But that does not mean that yours is not the best at 35 of course. Just that it's still higher than most.
What tire and wheel combo are you running? What is the max pressure rating on the side of the tire? And finally, how is your tire wear?
On the rear tires you can easily see if they have more pressure than needed by looking at the point where dirt is on the center of the tread and where it stops. Where it stops is usually where the tire tread is not touching the ground. Or not touching as much.
The trick is to lower the pressure until the dirt/wear pattern is right out to the edge of the tread, but not further around the edge. This is just about perfect for this load. If you regularly carry a heavy load, then by all means leave a little extra pressure in the tires as a safety practice. But if not, leave it running all the way out to the end of the tread.

Very curious about your setup. If 35 is your proper go-to pressure, love to know more about your tire combination. We're always hunting down information on each other's tire pressures and conditions.

Thanks

Paul
 
OP
OP
N

navi

Full Member
Joined
Jul 17, 2020
Messages
155
What makes you think it was redone? Records showing a rebuild or something like that? Are they still factory colors? Maybe they were just gone through and fixed a few flaws, rather than replacing.



Not too odd, since even though yours is before Ford offered them (first time in '76 I think?) a lot of people would add another horn so that we could play with the grownups back then. Most vehicles of the era had two horns, while Broncos got one relatively anemic one.
So having two is a good thing, but it wears out the horn contacts under the steering wheel much quicker.

Your '73 most likely does NOT have a horn relay, so the clicking you're hearing is either the horns have worn out/rusted inside, the horn button contacts need renewing, the ground at the horn itself is not sufficient, or something else is keeping the full current from making it to the horns.

Easiest way to verify the first half of that is to run a jumper wire straight to each horn wire. With the horn still bolted to the body, a jumper wire will make a good horn honk very easily.
Check to see if you have one or two wires. Factory horns were single wire and the ground was through the mounting bolt. If your Bronco has been re-painted and/or is a bit rusty, you might not be getting a good ground to the horn.

If they honk, you can then move up the chain of command and find out what else is causing the problem.
With the old system the full current to the horn passed up into the column on one wire, then through the copper/brass/whatevertheyremadeof contacts and then down another wire to the horns. All that current flow, especially doubled with two horns, wears out the contacts. You can sand them smooth of carbon buildup, grease them up with dielectric grease and they may be good for a few months to a few years, but the best way to get the horns to work better and the button to last longer is to install a horn relay.




Well there's your problem right there. And only you'll be able to find out what came loose, or which fuse blew.
A new aftermarket radio might have it's own inline fuses, and might no longer use the one in the fuse panel. But you might as well check all the fuses anyway, just to rule it out.
As with any vehicle this age using glass fuses, remove them all, clean them, then put them back in. Gives the electricity a fighting chance of making it through the system unmolested.
Then just go on the hunt for loose, or broken wires which only you will be able to find. Could be as simple as reaching under and moving wires around until it works. Or it could be the way you spend the next few days of your life on your back with your neck twisted into an "S" shape under the dash!%)



Wow! Down to 35? What were you running before?
Most of us are down in the 25-30 range at the most. But that does not mean that yours is not the best at 35 of course. Just that it's still higher than most.
What tire and wheel combo are you running? What is the max pressure rating on the side of the tire? And finally, how is your tire wear?
On the rear tires you can easily see if they have more pressure than needed by looking at the point where dirt is on the center of the tread and where it stops. Where it stops is usually where the tire tread is not touching the ground. Or not touching as much.
The trick is to lower the pressure until the dirt/wear pattern is right out to the edge of the tread, but not further around the edge. This is just about perfect for this load. If you regularly carry a heavy load, then by all means leave a little extra pressure in the tires as a safety practice. But if not, leave it running all the way out to the end of the tread.

Very curious about your setup. If 35 is your proper go-to pressure, love to know more about your tire combination. We're always hunting down information on each other's tire pressures and conditions.

Thanks

Paul

The tires are 33" general grabber AT with a max pressure of 50. I made the mistake of inflating to 45 psi, not even thinking about the ride stiffness, just that it was more technically correct than I had been running, which was about 33 psi. :eek:
It was jarring, probably shook the speedo cable loose. After that I checked the forum again and saw people running at 30-35. I didn't see people posting about going below that pressure though.

The wires just don't look 50 yrs old. There was a major rebuild on it about 20 years ago, but I don't see any wiring harness receipt.
 
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OP
N

navi

Full Member
Joined
Jul 17, 2020
Messages
155
Grounds,
Negative battery post to the engine block behind the alternator.
negative post to the body inner fender behind the battery.
starter solenoid to the fender well grounded by its mounting bolts.
Voltage regulator by its mounting bolts to the firewall or inner fender depending on when your bronco was made.
intake manifold to the fire wall.
rear taillights ground to the frame at the rear driver side frame by the bumper.
Dash grounds to the body mounting bolts and gauge grounds to the dash by its mounting bolts.

If this was my Bronco I would run a ground from the gauge cluster mounting to the body tub. and I would add a ground to the frame from the engine ground connection

as for horn depends on whether your hazard flasher is on the dash or the column. they both switch to ground through the steering column. the early sought ground through the steering shaft down through the steering box trouble starts here if some one replaces the steering coupler. factory steering couplers had continuity through the rubber doughnut in the later models. after market stuff doesnt always do that so you have to provide a jumper there. early dash mounted flashers had the horn direct to operation. Later Broncos with the flasher on the column used a relay for the horn mounted on the front fender well on the passengers side. ground went up through the steering column doughnut went through the horn switch down the column to the horn relay. the mounting bolt is ground for the relay so it must be a clean mounting. it is a very odd relay being a 3 tab relay. horn switch operated the relay and the relay sent power to the horn. horns themselves were grounded by their mounting bolts.

Thanks, it looks like I got some work to do. ;D
 
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