xj750K Maxim Horns sound weak

1983 xj750K Maxim. Has a new fuse box and new connector to fuse box.

Installed a pair of NOS horns, but both the Low Tone and High Tone horns sound weak. Prior to installation, I bench tested each of them and they seem to work properly, as loud as they should be. They are wired properly on the bike according to the wiring diagram. I also tried using dialectic grease at each of the horn terminals, but no improvement.

My question is, what would cause the horns to sound weak?
A bad switch?
A bad ground? As far as ground goes, when I switch on my turn signals then my running lights and warning lights dim when the signals are lit up.
A bad hot wire?
There is no horn relay, correct?

 

The innards might be dirty.

 

except he said on the bench test they sounded fine.

I'd bet on a bad ground

 

Dirt can move. Easier to check that before looking for a bad ground.

 

Horns are new, work great when I bench tested them yesterday. I did open one up and inspected the plastic channel and found they look new inside, no corrosion nor dirt for that matter.

 

No horn relay. I’d start with ground personally.

 

the horn button is the ground for the horns





hook the brown wires up and use a jumper to ground horns if they sound correct then issue is pink wire through button to ground

 

horns do sound different when mounted to bracket

 

Horns are always "hot" (via the brown wires to horns); pushing the horn button completes the ground circuit (pink wires to horns). It sounds like a bad ground either inside the control switch or on the black wire coming off of the control switch to the harness.

It sounds like a bad ground either inside the control switch or on the black wire coming off of the control switch to the harness...……


The black wire inside the control switch has a small ring terminal attached to it and is screwed into a hole on the bottom half of the control switch...……..that provides the ground circuit for the entire left control switch electrics. A poor contact at that point can create all of the problems with the left control switch functions. Also, the metal "cage" surrounding the horn button internals also has to make good contact with the switch internal housing, as that's how the ground circuit for the horns (pink wire) actually "contacts" the black ground wire for the switch.

Executive summary: open up the left control switch and inspect the ground wire connection to the lower housing. To be sure, carefully use alligator clips (or a separate length of wire) to create a separate ground back to the battery neg. terminal, and see if the performance of the various functions improves.

 

Great info, thanks! Although, Late last night I checked voltage to the pink wire at the horns and multimeter read less than 12v. That’s with fully charged battery on a trickle charger and the battery itself read 12.83v. I wonder if the rectifier is suspect...unless that only matters with the engine running producing current thru the stator.

 

dirty connectors will cause voltage drop , so will every component along the line. battery connectors to battery cables(maxim uses those metal bars) connector that runs to main fuse, fuse, ignition switch connectors in and out, ignition switch back to signal fuse and those pesky splices along the brown return wire to fuses. also the horn switch and that ground wire in control bet its got some corrosion on it. start cleaning them.

check voltage at battery and output side of main fuse. any voltage drop will point to connectors that need cleaning. then from output of main fuse and compare to input of remaining fuses. voltage drop would indicate dirty ignition switch.
compare and clean as you go. not much you can do about the splices except change the wire.

you could use horn wires to control a relay for the horn and run direct to battery with a fuse to relay for power for horns.

dirty connections are the culprit for many issues and are often overlooked.

 

Do you have a particular relay in mind? Would any of the stock relays work? I have spare relays. Also have a spare wire harness to harvest wires and connectors from.

 

this would work
https://www.summitracing.com/parts/bch-0332209150/recommendedparts

min amps would be 10 for fuse size

 

I replaced the horn in my XJ550 years ago, and noticed that if I didn't get the mounting bracket just right, they sound anemic on the bike. As soon as I loosen the bracket, they get nice and loud, while still attached to the bike's circuit. I had to play around the bracket and use a washer or two to space the bracket from the frame, and tighten the bolt just enough to keep it from moving, to get the horn to sound right.

Googling confirms others have had the same problem with mounting it just right.

 

For reference, similar to the one I just bought on ebay, here's another Dual Horn Relay Wiring kit:
https://www.ebay.com/itm/Car-12V-Ho...871584?hash=item4b64c04da0:g:p0UAAOSwE9Jc46yx

Attached are a couple images from that listing that would help as a guide for wire installation.

 

that's the way it should have been done from the factory

 

cost savings to meet marketing price point.

Yamaha could not make up its mind on headlight relay Maxim 750 does not have a headlight relay headlight runs through starter button