Need help with lights

[Brett James-McCall]

Right chaps, you may have seen from my build thread I have a problem getting my olights to work correctly. Need help!

The Setup
Two Lucas Switches as per SGT

31788
4 - Feed (Brown)
7 - Side/Tail (Red)
8 - Jumper to next switch (Blue, but now Black, as I messed up..)

31780
1 - Jumper
6 - Dip Relay (Black/Purple)
8 - Main Relay (Blue Yellow)

The Problem
Apart from 'It No Work', here we go

Flick Sidelights on, they come on. All good

Go down one position and then it jumps to the next switch. At this point yes, 12V comes on and confirmed 12V at the Relay as well - but nothing. The same is for the mains.

The relays have power, they are the top two below



Now, when I short out the Relay Feeds to the chassis they switch. So it's an earth problem, right?

Have a look at the picture, there is no earth on the relays, the power loops; also, there is no earth wire in the loom for the lighting. So how is it supposed to work?

To confirm, the starter relay does trip when you turn the ignition key, so there is no problem there (but it also has an earth in the relay!)

This is doing my head in, please someone help me!!

 

[Andy Green]

Brett,
It's difficult to tell why it won't work remotely. You you need a copy of the wiring schematic that goes with the wiring harness from SGT. That way you'll quickly diagnose what's gone wrong or is missing
Regards,
Andy

 

[Brett James-McCall]

I don't have a schematic Andy. Only a table of connections

 

[Jim Cowden]

Brett

most relays run with the Bosch system

30 is from power supply fused (battery)
87 -87a is to lights
86 is a ground
85 is a power supply from your switch.

85-86 is to an electro magnet, it requires a ground and power to pull it down.
when it does it contacts the term across 30 and 87-87a, main power supply to lights is delivered.

your relays may have a pic printed on them.
I always disect the relat into 2 sections ,high current 30-87-87a /low current 85-86

You can also supply power to term 85 and ground term 86 through the switch on the dash but i dont think you have wired it that way

My guess you need a ground on either term 85 or 86 as you have already pointed out.
you need a wire from you switch going to either 85-86,what ever is not being used by the gound wire.

power supply on 30, lights on 87-87a

Jim

 

[Stephen Ducker]

Quite right Jim, but don't forget 87a is normally closed & 87 is normally open (ie trigger coil off). With the trigger coil powered they reverse positions.
Thus a single 5 pin relay could be used to switch between high & low beam for instance or a 5 pin relay like this can be used as a standard 4 pin by ignoring 87a and leaving it disconected.

Brett seems to have a pair of 4 pin relays & working backwards from the terminal numbers as Jim suggests should be helpful. As long as the pin connectors are in the same positions on the loom & relays, be careful !

 

[Brett James-McCall]

Thanks chaps, will take pics of the relay tomorrow

 

[Jim Cowden]

Had closer look at your pic
I am assuming that your top wire blue/white trace is from your dash switch and it is 12v supply, then you need to remove blue loop wire and make that a ground.

Steve yes bosch do have swithing relays as well as 5pin duel supply.
But as you stated brett has 4 pin so he should be ok as term # will still be ok .

Jim

 

[Brett James-McCall]

Morning Jim, Hope all is good in Sydney, certainly sounded that way when my Sister in Law called from Cremorne an hour ago

Anyway, down to business. Here is the view of the relay circuit and pin layout. It is a 30-87-86-85


IMAG0408 by Brett-GT40, on Flickr


IMAG0409 by Brett-GT40, on Flickr

and here's a better pic of the wiring to the relay holder


IMAG0411 by Brett-GT40, on Flickr

So the way it is wired up at the moment is

87 - Output to Headlights: Blue/White
30 - Main Input: Blue

86 - Input from Lucas Switch: Blue/Yellow
85 - Main Input Looped: Blue

So would I need to remove the Loop to pin 85?

 

[Andy Green]

Brett,
have a look at the attached, as this is the basic schematic you have described. Use a meter to then ensure the relays/harness is then following this
Regards,
Andy

 

[Brett James-McCall]

Thanks Andy, I've been out in the garage (two days in a row - who knew!!) and replaced the loop on pin 85 and changed it to a earth harness and...


IMAG0412 by Brett-GT40, on Flickr

Dips and Mains all work and switch.

I know having spoken to Adam before, that the early looms they got, they used to have problems. They believed their supplier was getting his apprentice to put the looms together and there were a lot of mistakes, which he says have all now been rectified along with other improvements going into the loom. Looks like I have one of those looms - I know this as well, as the main beam warning light had been wired up to the wrong wire and would have come on when the dips were on. It's just frustrating from my point of view, as I guess I expected it to plug and play and I have spent days (if not longer) trying to figure out what I was doing wrong and had just not considered the earth (or lack of) on the relays

 

[Ian Anderson]

Brett

Was that a bright idea :idea: or your car finally showing there is light at the end of the tunnel?

Another milestone now ticked off that list - perhaps this summer on the road?

Have a great day - especially if you are in the garage!

Cheers
Ian

ps isn't this what the forum is for - helpfull suggestions freely given and then the end result a happy person with something working!

 

[Stephen Ducker]

Well done Brett, another step closer to VED at work next year ? !

Regards Steve

 

[Brett James-McCall]

Steve,
I say every year that I'll get it to VED... fancy coming round to help get it there ?

Brett

 

[Stephen Ducker]

Good answer Brett !

Once the good lady has finished painting the ceiling I'll send her around with her wickes roller to do you some Le Mans stripes.

All the best, Steve
(So are you off to head office mate ? promotion I hope !)