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Headlight relays
pekwah1 - 16/1/13 at 02:53 PM

Hi guys,

I'm getting all confused over relays.

I currently have sierra switchgear (i believe switched earth) and am thinking of changing to an escort switchgear instead (switched positive?).

My headlight relays are wired for the switched earth, so to change to a switched live, can i just change the permanent live that i have in my relays to permanent earths instead and then wire up the switchgear?

Hopefully this makes sense...!

Regards,
Andy

loggyboy - 16/1/13 at 02:55 PM

Are they 3 pin relays with a shared earth?

pekwah1 - 16/1/13 at 02:56 PM

4 pin, 30, 85, 86, 87

loggyboy - 16/1/13 at 02:58 PM

So you only need to change what wires go to pins 86 & 85, the rest can remain the same.
I hope!?

pekwah1 - 16/1/13 at 03:07 PM

so can i just change 85 to a hard earth and then use 86 as a switch live from the stalk then?
sounds too simple, i don't like it! :p

loggyboy - 16/1/13 at 03:36 PM

This is how read it -
Currently the positve feed is to the the switch which connects to pin 85 or 86 and then the opposing 85/86 then goes to earth -
However the new set up needs a feed from 12v+, through 85 or 86, then out 85/86 to your switch which is earthed.

The 30 87 pin that switches the light on is unaffected by 85 or 86 as all it knows is if 85/86 is on or off.

pekwah1 - 16/1/13 at 03:37 PM

so as long as 85/86 are completing a circuit (positive to earth) then it will work.
That makes sense, so by that logic then i can just swap round 85 and 86!

loggyboy - 16/1/13 at 03:49 PM

quote:
Originally posted by pekwah1
so as long as 85/86 are completing a circuit (positive to earth) then it will work.
That makes sense, so by that logic then i can just swap round 85 and 86!


Lol not quite, 85/86 are currently completing a link to earth, you need them to complete a link from positive.

You need to trace the lead that leads from 85or86 to earth and connect that to positive, then trace the lead that runs from switch to positive and change it to earth.

snowy2 - 16/1/13 at 04:02 PM

The relay won't care how its switched.....basically you have a live feed to the relay and up to a switch that earths it and you want to do the oposite. simples.....earth the wire on the relay currently supplied with a live (85/86) and the other end still connects to the switch which in stead of going to earth is now live....

pekwah1 - 16/1/13 at 04:02 PM

ok you're confusing me all over again now!

I am assuming that these (rubbish) diagrams below are both fine for the relay:

1.
+ (30)-----(87) to lights


+ (85)-----(86) -


2.
+ (30)-----(87) to lights


- (85)-----(86) +

loggyboy - 16/1/13 at 04:12 PM

You confusing yourself. Its not the relays that need anything changing. its where the wires go to before and after the relay.

Swapping the cables that go to 85 and 86 will do nothing.

pekwah1 - 16/1/13 at 04:14 PM

i didn't literally mean swap the cables, i meant swap the polarity going to each point on the relay..

[Edited on 16/1/13 by pekwah1]

loggyboy - 16/1/13 at 04:20 PM

Thats the same thing!

Hope this helps?

SteveWallace - 16/1/13 at 04:50 PM

One version of the Sierra switch is

Pin 85 to the dip switch
pin 86 to fused live
pin 30 to fused live
pin 87 to the lights

The other version is

Pin 85 to earth (i.e - ve)
Pin 86 to the switch (which then connects to live via the other side of the switch)
Pin 30 to fused live
Pin 87 to the lights

I.e the difference between the two is in how the solenoid in the relay is wired. In the first case its the switch that goes to earth and the relay is connected to the fused live live supply. In the second case its the switch thats connected to the fused live supply and the relay thats connected to earth.

pekwah1 - 16/1/13 at 06:27 PM

Nice one guys thanks for the help...
I'll have a play over the weekend and report back!

GOJO - 16/1/13 at 07:35 PM

quote:
Originally posted by pekwah1
so can i just change 85 to a hard earth and then use 86 as a switch live from the stalk then?
sounds too simple, i don't like it! :p

Yes