horn/headlights related issue

[iwishiwasme67]

Trying to track down an electrical issue with my dash lights not working I stumbled across something else. I unpluged the entire instrument cluster and plugged it back in to ensure all connections were
tight. Well in doing so my horn started working but ONLY when my headlights are on. PO disconnected an aftermarket stereo and the dash lights quit working. (Still not working)
Why would my horn work only when the headlights are on?

 

[tag3]

Just kidding, thinking it is a wire that the stereo was hooked into that is now connecting the horn to the light circuit.

 

[Slow Left]

The horn and the headlight circuits share the same fusible link.

If you look at the wiring diagram and trace the Red (R) wire that comes off a fusible link on the positive terminal of the battery, you will see that it leads to both the Horn-Hazard fuse and then onto the Headlight Relay.

But other than that I can't see that there is any cause and effect relationship between your horn and the headlights.

I would suspect that if you pull the steering wheel and inspect the horn pin and the contact plate for the pin on the back of the steering wheel you will see that the horn pin has worn down.

If so, replace the with a new horn pin and flip the contact plate on the back of the steering wheel around (or get a new contact plate as well) and then rerun your experiment to see if the correlated effect goes away...

see:
https://forum.ih8mud.com/threads/horn-button-losing-ground.825986/

 

[iwishiwasme67]

The horn and the headlight circuits share the same fusible link.

If you look at the wiring diagram and trace the Red (R) wire that comes off a fusible link on the positive terminal of the battery, you will see that it leads to both the Horn-Hazard fuse and then onto the Headlight Relay.

But other than that I can't see that there is any cause and effect relationship between your horn and the headlights.

I would suspect that if you pull the steering wheel and inspect the horn pin and the contact plate for the pin on the back of the steering wheel you will see that the horn pin has worn down.

If so, replace the with a new horn pin and flip the contact plate on the back of the steering wheel around (or get a new contact plate as well) and then rerun your experiment to see if the correlated effect goes away...

see:
https://forum.ih8mud.com/threads/horn-button-losing-ground.825986/

thank you a ton!!!!

 

[Slow Left]

thank you a ton!!!!

No worries...a new horn pin from Toyota shouldn't run more than several dollars...but if you have a .22 shell casing laying around, then you can just slide that over your existing pin and you should be good to go.

If you pull the steering wheel, inspect the pin and compare it to the picture of a new pin in the link I posted above, then you should know if you need to replace it. Also, flipping the contact plate on the back of the steering wheel should work...1 time...

 

[Slow Left]

Why would my horn work only when the headlights are on?

The Horn/Hazard circuit shares the same fusible link (labeled R on the wiring diagram - so the fusible link with a red wire) as the Headlight circuit.

It also might be that you have a fusible link that is intermittently shorting, so by coincidence, when the lights are working then so is the horn.

You can check to make sure that you are seeing 12V+ on the far side of each fusible link (specifically the Red one, since that is the one that the circuits are on).

 

[gregnash]

The Horn/Hazard circuit shares the same fusible link (labeled R on the wiring diagram - so the fusible link with a red wire) as the Headlight circuit.

It also might be that you have a fusible link that is intermittently shorting, so by coincidence, when the lights are working then so is the horn.

You can check to make sure that you are seeing 12V+ on the far side of each fusible link (specifically the Red one, since that is the one that the circuits are on).

This is what happened to me, I had a corroded fusible link connection on the outside of the connector that attaches to the positive battery cable. This "occasional" short caused the metal spade inside the connector to heat up and burn/melt the plastic inside which had me on a hunt to find another terminal connector for the positive battery side as the original was connected to the original battery cable. Go check those connections ASAP as it can be a B#%*@& to get everything afterwards (the fusible link itself is still available by Toyota).

 

[iwishiwasme67]

Well I feel dumb... it appears i just have
The typical FJ60 Horn issue. I think what was happening was I had the lights on and the steering wheel turned enough to engage the contact ring and make the horn work... Im chalking this up to having a new born and not sleeping much...ugh! Sleepy time very important before screwing around with the truck.

 

[Slow Left]

The typical FJ60 Horn issue. I think what was happening was I had the lights on and the steering wheel turned enough to engage the contact ring and make the horn work...

How did you come to this conclusion (what measurement did you take)? Was it that you were able to get the horn to work once or twice with the headlights off? Or did you pull the steering wheel and examine the condition of the horn pin and plate?

Don't worry, people dedicate a lifetime to learning the principles behind how machines like this FJ60 work...the benefit of MUD is that you get to ride that learning curve faster and on an as need basis...!

 

[iwishiwasme67]

I figured I would isolate the horn issue and diagnose it first. I pulled the steering wheel off and noticed the contact ring was about done and the pin was nearly non existent. I pulled the new ring and pin out of the wifes to test and it worked perfectly. So now that I have that put to bed im back to tackling the dash light issue. My wife is pretty confident that its an issue with the rheostat. So this weekend we'll tear into it and figure it out...I hope...

 

[66 FJ40 Landee]

Can someone share a picture of the fusible link or tell me where it is located in the engine compartment?
Thank you in advance.

 

[OSS]

picture of the fusible link

Connected to battery terminal

 

[66 FJ40 Landee]

View attachment 3226876

Connected to battery terminal

Thank you