Horn Doesn't Work--help

[cal]

I just bought a used GS300 and the horn doesn't work. Is there a fuse for the horn?

Another problem I encounter is the driver's side rear window is acting weird. The window goes up with the switch but after I release the switch, It goes half way down on it's own. Is this normal?

What are the normal maintenance for the car?

Thanks

[GuyTelefunken]

Look in your manual. Yes there is a fuse. Fuse no. 13 in the underhood fuse block, passengers side. Horn relay is in the underhood junction block, drivers side.

If the relay is clicking (can be felt while holding the relay) when you press the horn on the steering wheel, the fuse is good, and most likely the relay is as well. Check for power at the horn connectors with a test light. If there is power at the horns, then the horn's are most likely bad. It is unusual for both horns to go at the same time, but not unheard of.

If the relay is bad, it will either not click or isn't making contact to send power to the horns.

In the unusual event that the relay is not clicking and the fuse is good, it is remotely possible that something happened to the switch or wiring from the horn pad to the relay.

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As far as the window goes, it's most likely the motor. If the motor is worn or close to worn out (perhaps it sounds noisy, or is moving the window more slowly than the others) it will draw too much current when the window is fully closed. The ECU will interpret this as an obstruction in the path of the window and activate the "anti-pinch" feature. The window will roll down. The motor also incorporates am internal limit switch which also may be bad.

Horn_Fuse___Relay.pdf

[cal]

Guy,

Thanks for the reply. Is there any way I can have your email address. I have other questions for you. If you would like, you can also email me at corkycalvin@yahoo.com.

I was not able to get the relay diagram.

Thanks

[era57]

Look in your manual. Yes there is a fuse. Fuse no. 13 in the underhood fuse block, passengers side. Horn relay is in the underhood junction block, drivers side.

If the relay is clicking (can be felt while holding the relay) when you press the horn on the steering wheel, the fuse is good, and most likely the relay is as well. Check for power at the horn connectors with a test light. If there is power at the horns, then the horn's are most likely bad. It is unusual for both horns to go at the same time, but not unheard of.

If the relay is bad, it will either not click or isn't making contact to send power to the horns.

In the unusual event that the relay is not clicking and the fuse is good, it is remotely possible that something happened to the switch or wiring from the horn pad to the relay.

-------------

As far as the window goes, it's most likely the motor. If the motor is worn or close to worn out (perhaps it sounds noisy, or is moving the window more slowly than the others) it will draw too much current when the window is fully closed. The ECU will interpret this as an obstruction in the path of the window and activate the "anti-pinch" feature. The window will roll down. The motor also incorporates am internal limit switch which also may be bad.

The horn in my Gs400 stopped working as well and I just wanted to say thank you for the awesome post because it answered all my questions. The diagram was exactly what I was looking for. :D

[carrzo]

Guy --

Ditto, your response was great, many thanks. Here's how I fixed mine with your help for $36.

1) On my 2005 Sc430, and I suspect others models, there are actually two horns righ next to each other between the radiator and the front grill.

One is for high tones and one is low. This if for when you just tap the horn in a friendly way as opposed to pouncing on the horn with a more aggressive toot.

2) The relays are in a box on top of the engine, on the drivers side. There is a map inside the relay cover that shows you where the relay is for the horn.

I checked the relay by taking the relay box cover off, having the ignition on and having someone press the horn intermittently. Can't just press it once, else you might miss the clicking. . I could hear the relay was was clicking. That told me that both the relay and the fuse are working, since a blown fuse would prevent the relay from clicking. If you don't hear the clicking, it is a $7 replacement part at AutoZone, but see next step first just in case.

3) So if you don't hear the clicking, next check the fuse. This is easy as well, go to the fuse box (on my car it is on the passenger side of the engine) take the cover off and either it or the manual will show you which one is for the horn. My fuse was a red, with 10 printed on it. really stood out. There is a gray fuse pulling tool inside the box, take it out, it's like a tweezers, and pull out your fuse. You can then visually check it by holding it up to the light and seeing if the wire inside is burnt out. They make them pretty obvious to the naked eye, because frankly that's what fuses are supposed to do -- burn out and protect the rest of the electronics.

4) The good news is if your fuse is blown it's a quick fix and very cheap to replace. The challenge is you're hoping it was a one-time surge that made it blow and hopefully something not more chronic in your electronic innards.

5) Ok, so if both your fuse and relay don't seem to be the issue, then you unplug the wire connector from tone of the horns themselves. This is simple, there is a tab on the plastic connector, you press the tab town, wrestle with it a bit, and it separates from the horn.

6) Get a circuit tool that measures current, you can get them pretty cheap. Stick one end into the connector and put the other to ground, a nearby bolt on the engine should suffice. Again have someone tapping the horn with the ignition powered on. If you see the needle moving that's a good sign -- current is getting to your horns and they are the cause, as opposed to some electronic wiring goblins that are ready to bring you some doom and hefty bills.

7) In my case, I was getting current to the horns. Bought two replacements, $18 each at AutoZone. One high, one Low. My high one was on the left, for what it's worth. You'll know because when you remove your old horns (one bolt for each -- easy!) they are labeled with their decibels or "H" and "L" or some such.

Wiring from the connector fit right into the existing car connector -- no re-wiring needed. The other connector coming out of the horn came with a grounding wire, just attached it to the bolt that hold the horn to the engin.

Replacement of both horns took 15 minutes. Which is about $400 at my local dealer, I'm sure.

Happy motoring !