Upgrade Horn relay to Bosch Relay

[Double_d]

Hello,

 

Been searching for this, but nothing good has come up. Anyone dones this before? Upgrading from the stock oem relay to bosch 5pin? If so how would I go about this?

 

I have little knowledge about relays but this is what "I" thought it'd be.

 

85: Black / Green

86: Ground

30 (common): Green / Yellow

87a: Ground

87: 12V Green + to Horn

 

Any suggestions or help would be koo!

 

Thanks

[DanielC]

I do not know about a 510, but I do know about a 521.

A stock 521 horn relay has power in and coil positive on one terminal.

The coil is grounded by the horn button. This causes the relay coil to the apply power to the third terminal, a wire going to the horns. The horns are grounded.

In "bosch" apply power to pin 30 and 86. Pin 85 goes to the steering column. Pin 87 goes to the horns.

[Laecaon]

Yea you only need a bosch 4 pin. You can use a 5 pin, and not use 87a.

 

Wire it up as Daniel said, it works the same on a 510.

 

You will probably need to splice on another wire for the one positive from the harness.

 

So:

85=Black Green (ground when you push the horn button)

86&30 get +12 power (currently the green red wire is +12, but you need to attach this to 2 terminals on the bosche relay)

87= positive passed though to horns. This is indeed green.

[Double_d]

what about the Green Yellow? GY is the brake light switch and it also goes to the horn relay.

[DanielC]

On a 521, the same fuse powers both the brake lights, and the horns. (through the horn relay)

The brake light wire is Green/Yellow on a 521.

[Double_d]

I understand that, I was wondering where the GY wire would go on the bosch relay. the stock relay for a 510 is Green , Green yellow , green black.

[DanielC]

The horn relay wire colors on a 521 are Green, Green with Blue stripe, and Light Green with Black.

Green goes from the relay to the horns.

Green with blue stripe goes from the fusebox to the horn relay.

Light green with Black goes from the relay to the steering column.

 

Obviously, the colors are different than a 510. If your green with yellow wire supplies power to the brake light switch, I would think it should be connected to the same wire that is always hot on the horn relay.

 

My wiring diagram shows the power wire for the brake lights (Green with Yellow) connected to the fuse box, and the power wire for the horns (Green with Blue stripe) connecting to the same fuse.

[banzai510(hainz)]

I was wondering where the GY wire would go on the bosch relay????????

so you want your horn to go off when you hit the brakes.?

 

Its GY shares the same fuse thats it. otherwise I dont think it has anything to do with the horn relay. Far as I know the relay for the brakes lights is under the brake pedal, well say a SWITCH

[Double_d]

That's what I thought too. But GY brake switch is under the brakes, then if you follow it it's also on the horn relay.

[Double_d]

Alright so some peeps from 510realm helped me out with this dilemma. So for those who want to know how to use updated relays for the horn here's the diagram.

 

I was pretty close just didnt need the ground.

 

86: Green/Yellow (12VDC)

85: Black/Green (Horn Ring switch)

30: Green/Yellow (12 VDC) <-- Brake Light Switch

87a: Green (Horn)

87: OPEN

[datzenmike]

You can also use Nissan relays from the 720/280zx/S110 and S12.... mainly because they are free for the taking from a wrecking yard. D-21 and WD-21s have some too. There are 4 and 5 wire ones and the terminals and where they go inside the relay is cast into the plastic so you can see it.

 

 

[Laecaon]

Cool looks like you were given bad info...

 

You want 87 not 87a.

 

87a is constantly connected to 30 when there is no voltage difference between 85 and 86.

 

When you ground 85 by pushing the horn button, you have 0 volts at 85, but now 12 volts at 86. That is a 12 volt difference. The coil in the relay will now switch the contacts. Now the 87 terminal will connect to 30, and not 87a.

 

 

And power is power, why wouldnt the green/yellow and the green/red be the same? Obviously by the wiring diagram, there is simply a splice in the harness.

[Double_d]

^ yah that was a typo, meant to put 87 not a.