Rev 5 Horn Not Working/ Wiring Help

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Dandenio
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Rev 5 Horn Not Working/ Wiring Help

Post by Dandenio »

Hi Guys,

I recently purchased a rev 5 MR2 and it came installed with an after market MOMO steering wheel. The horn however does not work.

When the button on the steering wheel is pressed I get no movement at the relay. I’ve tested the relay and it works and I’ve also tested between the relay and the horn and this also works. The horns have both been tested with 12v and they both work.

The problem I have lies between the relay and the steering wheel. While doing research about this online and on the forums, everyone seems to be talking about the “Green” Horn wire. I cannot for the life of me find it however ahah. The previous owner has soldered a wire to the brass ring behind the wheel and is a good contact. I did test for continuity between the socket at the relay and the brass plate at the wheel and the were not connected.

The issue I believe I have is that i cannot see anything connected to the metal disk behind the brass part and I cannot find what it should be connected to.

I’ve attached some pics and hope that someone on here has a similar setup. Any help would be greatly appreciated, like I said I’m new to owning an MR2 so I’m trying to learn as much as possible. If I can provide any more info and/or better pics, please let me know.

Many thanks,
Dan


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rgb
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Re: Rev 5 Horn Not Working/ Wiring Help

Post by rgb »

the old owner probably didn't get the horn to work so you need to start from scratch . the issue will be in the plastic ring behind the boss .I thought the horn had one wire coming through the column and you have to earth it to make the horn operate . does it have driver airbag wires . I had these problems about ten years ago so I cant remember
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Dandenio
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Re: Rev 5 Horn Not Working/ Wiring Help

Post by Dandenio »

I’ll take the plastic ring off tomorrow and take a look. I can’t seem to locate any airbag wires, however there is a electrical board under the wheel if this has anything to do with the airbag. I had a look at it and couldn’t figure out if it was for the indicator/ window wipers. Every post I seem to look at about the horn seems to have completely different wiring ahaha. I’ll post my findings.
Many thanks
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Re: Rev 5 Horn Not Working/ Wiring Help

Post by SonicSW20 »

If it's a UK car the original airbag is entirely mechanical, no electrical connection to the air bag at all. That is why it does not have an SRS warning light.

US and Japan market cars have a different electrical airbag system.
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Dandenio
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Re: Rev 5 Horn Not Working/ Wiring Help

Post by Dandenio »

Ah, yes this would make sense for why I can’t find the airbag wires ahah. The car is UK spec, thank you very much for saying as I would have been looking/ wondering where the wires were for ages :th:
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Re: Rev 5 Horn Not Working/ Wiring Help

Post by shinny »

It looks like someone has really butchered the slip-ring - probably because the steering wheel boss looks like junk too. (Certainly not designed to fit an MR2) I would start by getting a replacement from a breaker, which probably means buying the entire stalk assembly, and the correct boss for the car.

You can check out my video so see what it should look like and how easy fit a steering wheel (including getting the horn to work) when you use the correct parts. Particularly, note the rectangular hole in the base of the boss:

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Dandenio
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Re: Rev 5 Horn Not Working/ Wiring Help

Post by Dandenio »

I agree with you mate, after further research I'm pretty sure that the existing boss is a lower quality one. However, i would like to get the horn working on it and purchase an authentic MOMO one in the near future, along with your recommendation of possibly a new steering assembly if the existing one is knackered when removed.

I also removed the plastic surround covering the metal disk at the base of the boss. This uncovered a few things, the first being a black box with an electrical board inside. This was slid over the metal disk, I believe this to be something to do with the power steering system? But i may be wrong ahah

The other thing was 4 wires connected to the disk, these being White, Black, Pink and Green/Red. I'm not sure what each of them do but id assume one of them is to do with the horn? but i don't know which it is, if any.

If there is anyone who has similar wiring, am i missing a wire by any chance

Thanks again for all the replies dudes :th:
Ive added some more pics bellow unavailing more

Cheers,
Dan


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Dandenio
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Re: Rev 5 Horn Not Working/ Wiring Help

Post by Dandenio »

Btw i've now watched all your vids on Youtube :laughing

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Re: Rev 5 Horn Not Working/ Wiring Help

Post by rgb »

getting a new boss isn't going to help , you need to get the horn working with no boss . find the horn wire behind the slip ring (plastic round thing that goes round the shaft) there cant be that many wires

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