Relays

[alfadave]

The relays on the loom on my sud S2 are looking iffy.

I've replaced a couple of small ones, no 15,16.

But there are 3 big ones attatched to the fusebox.

Shown in my red Haynes manual on P 108 as no 26,27,28.
Headlights,HRW and horn

Does anyone know if I can replace these with new, smaller, "cube" type relays?

[KevJTD]

The heated rear window and horn you can replace with any old 4 pin "make or break" relay. one with pin numbers 30, 85, 86, 87. 30 is power from battery, 87 is power out to what you're trying to use e.g. horn, 85 goes to earth, 86 is from the switch e.g. from the horn button/switch.

For the main beam one you will need a different one if you've the twin round headlights as they power all 4 rather than switch from dip to main. If they did switch from dip to main then you'd need a "changeover" relay, which as is described it changes power output from one terminal to another. these are 5 pin terminal relays (the extra output feed) with the same terminal numbers but the extra 87a in the middle.
for the headlight main beam you will need a double output one, again a 5 pin but the centre pin is labelled 87b which means it will power both 87 & 87b when energised.


there are plenty of diagrams on the net which show it in diagram form, handy to download and use to double check.

[KevJTD]

This webpage has some handy diagrams further down the page..


https://www.12voltplanet.co.uk/relay-guide.html

[alfadave]

Wow, thanks for that info Kev.
I've got ordinary headlights from a sud SC, so a 5 pin 87a......I think?

In one of your posts, you said you didn't know much about electrics.....Wrong!

[dave.armstrong]

This is a great guide and a great help Kev. Thanks

I have copied the guide from the internet and converted into a JPEG so hopefully everybody can download it and print it off.

Relays demystified!

[KevJTD]

Yes Dave, if you've ordinary headlights with one bulb that swaps from dip to main then you need a changeover relay, the 87a one as you say. Power from the battery comes in on terminal 30, goes out to 87 on dip then 87a when main beam is asked for which then switches 87 off.
Relays are really just like a switch.
Glad I can de-mystify them somewhat!

[StescoG66]

Some excellent explanations there thank you all. De-bunks it for me a fair bit.
So for a twin headlight arrangement then it's 5 pin with 87a and 87b - b being the centre pin?

[KevJTD]

Hmn, I've been studying the wiring diagram and trying in vain to remember the exact layout but something doesn't ad up.

I'd need to have a loom in front of me to get it right in my head, told you, I'm not really all that on electrics, just if they are there in front of me and can have time to study it I can figure it out.

The Sud lights (let's talk twin round Ti style lights here) work on the outers for dip and main beam gets the inners & the outers on. So the outers (dip) stay on with headlights . Min beam puts the inners on and the outers stay on.

So you'd need a 5 pin relay that powers 2 output pins when asked for main beam, one for the dips and one for the mains, so a relay with the 87 & 87b pins


If you had a relay with 87 & 87a pins then that switches power between those 2 pins when energised rather than powers them both or switches both off as per the 87b one...


Now studying the wiring diagram makes no sense to me at the moment...


This is the diagram I must have used to rewire VJM as it has some writing on it.


Relay 26 is the headlight relay.

Pin 30 is the power source, you can trace it back to the other relay but linked back to the fusebox where it will come from the battery.
Pin 85 needs to be earth, which is gained by you turning on the light switch in the car which thus creates an earth. Alfa often use this backwards way of doing things, early cars were very confusing!
Pin 87 goes to the No. 16 relay
Pin 87b also goes to the No. 16 relay and is linked to the dip beam feed wires through the fusebox.



What's confusing me is the main beam relay, No. 16 on the diagram.

The numbers on the diagram don't really match anything so that makes it harder to understand things.

Pin 30 is power from the battery, as normal.
Next pin along appears to be labelled 56 which comes from relay 26, from its' pin 87 which will be fed by that headlight relay when the dip beam is switched on. Wire coloured green/back
Next pin looks to be labelled F, traced along to the dip beam, also fed from pin 87b so will be live when dip beams are switched on, which makes sense.
86a appears next which is the feed to the main beams.
Last one goes back to the dip/main switch in the car so will most likely go to earth.



Now we know that the dip lights will need to stay on whether on dip or main, but why go through the main beam relay? Why not just have the first relay (No. 26) switch the dip beams on which would stay on regardless of whether main was asked for..then the main beam relay to switch the mains on....I need to think about this more...

[KevJTD]

Here....

[KevJTD]

Ok, got it. I think!

They should both be 5 pin double pin relays, the 87b ones. So they are either off or power 2 pins, 87 & 87b.


So when you have dip beam on the power goes through the relay 26 which feeds out to wires 87 & 87b which 87b goes on to feed the dip beams.

Main beam relay 16 is doing nothing.



When you switch to main beam then relay 16 sends power to 2 terminals, one feeds the main beams and the other terminal feeds back to the dip beam relay (which would now be switched off) which being it has linked terminals within itself then sends power back up the wire 87b and on to the dip beams again. Exceptionally over complicated!






Still doesn't make sense to me though.....

[dave.armstrong]

Hi Kev

Is it made more difficult than when the headlights are not on and you 'flash' then only the inners come on?

[alfadave]

Been fitting a loom from a T reg ti this week
The rear relay at the fusebox, shown as item 28 on the diag, has got 5 connections on my loom.
I wondered if 16 and 28 had been mixed up on the diagram?

[alfadave]

So, what I did, was simply replace like with like.
But the headlights won't work!
One for the auto elec to sort out

[alfadave]

Had the auto elec out for 2 visits.
The fusebox and relays have all been replaced with new.....

Except the largest relay at the rear of the fusebox, where he had to use the existing one,
Which switches the lights from dipped to main with a loud clunk!

[Kegsti66]

Result !!

[StescoG66]

My car had the wrong relay in the front fog port - pins 30 and 86 wrong way round - which I suspect is actually the horn relay but will check.
Anyway, can anybody tell me what this wee fecker does?

[StescoG66]

Can anybody tell me if this is the correct relay for main beam? As soon as I plug it in the main beam comes on. I think I need pin 87 plus 87b

[alfadave]

If you carefully re read the posts on 19 Oct.....I think the answer is there.

On my S2 sud, auto elec used an old large (60x40x30) relay for my headlights......maybe because i didn't have an 87b one available?

The old one is 5 pin, marked S, 30, 56, 56A, F .

[alfadave]

There seems to be a modern version of the old relay the auto elec used on my car for the headlights.

Have a look at vehicle wiring products item 72802.
Called a latching relay
Expensive though!

[StescoG66]

Can anybody post me a pic and schematic of the main beam relay from their car? Tried 3 different ones now to no avail......

[StescoG66]

Right folks - finally got the correct relay. If anybody needs to replace the main beam relay you need Durite 0-727-22. I bought one of the Bosch 0332019151 equivalent listed as compatible - but it didn't work either. I can confirm this Durite version works as it should. Now to sort the dodgy earths........

https://www.arc-components.com/0-727-22 ... -2135.html

[alfadave]

Glad you've sorted it with an 87b type relay

[StescoG66]

Sorry scrounging help again. As you can see, I have pulled out a relay from the fuse box to try to see what it does, as the Haynes book makes no reference to it. However, all the pins on it are testing as being negative polarity..... All the other relays work as they should. Can anybody enlighten me?

[StescoG66]

Re the pic above. That was nearly a year ago!!!! dear me. Anyway.... that mystery relay appears to be connected to the two orange wires at the brake fluid reservoir.