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switched earth relay
cd.thomson - 3/3/10 at 09:32 AM

re: my "simple" relay question thread.

Does anyone have a wiring diagram for a switched earth relay?

I can only find switched live diagrams which I believe are different.

Ta

t16turbotone - 3/3/10 at 09:48 AM

lets start at the beginning, so you have a relay with terminals 85 86 87 and 30?
and its for a horn?

cd.thomson - 3/3/10 at 09:49 AM

yes and yes.

The switch that operates the horn is also definitely an earth switch rather than a +ve switch.

t16turbotone - 3/3/10 at 09:53 AM

you using sierra coluum ?

cd.thomson - 3/3/10 at 09:54 AM

yep, new momo wheel and boss but it uses the original sierra copper ringed push centre horn switch.

(thanks for the help in advance btw!)

t16turbotone - 3/3/10 at 09:57 AM

ok...so you have two wires coming from the carbon brushes at the back of wheel?
when you push horn button these two wires make contact....?

cd.thomson - 3/3/10 at 10:02 AM

yes thats it. One of the wires is a brown earth and the other is a red/yellow wire which runs to the front of the car.

When i connect this red/yellow wire to one terminal on the horn and another specified green/yellow wire to the other terminal and press the horn button then the horn sounds. I therefore presume the green/yellow is a +ve wire from the battery.

t16turbotone - 3/3/10 at 10:14 AM

ok....connect red/yelow to 85, and green/yellow to 86..............ok
do that and see if relay clicks when horn is pressed....forget horn connections for now...see if it clicks

cd.thomson - 3/3/10 at 10:25 AM

I will try that later when I get in, and if it does click (which I assume is what we're hoping for), what then?

a +ve wire to 30 then a wire from 87 to one of the horn terminals and an earth from the other terminal.

I have twin horns so I will just run two wires from 87, one to each horn.

[Edited on 3/3/10 by cd.thomson]

t16turbotone - 3/3/10 at 10:43 AM

yep....youve got it, make sure you fuse circuit......good luck


tony

BenB - 3/3/10 at 12:08 PM

Doesn't matter whether you switch the earth or the live. If it click it's working

omega 24 v6 - 3/3/10 at 12:22 PM

quote:

Doesn't matter whether you switch the earth or the live. If it click it's working


It will if you use the setup he has as the sierra wirng at the horn push is a switched negative by default.

BenB - 3/3/10 at 01:13 PM

quote:
Originally posted by omega 24 v6
quote:

Doesn't matter whether you switch the earth or the live. If it click it's working


It will if you use the setup he has as the sierra wirng at the horn push is a switched negative by default.


surely that just means he has to put +ve to the other terminal? IE I mean it doesn't matter whether the switch is in the earth or the supply. If it's switched earth, just apply 12v to the other supply terminal and job's a good'un.