Relay Reconnection

[Macski]

Another for you guys. My Mr2 is an inport so has an after market fog light fitted, it has never worked. I am guessing the relay is broken but while removing the battery it got disconnected, well two of the four wires came adift, can someone advice me how to reconnect them?

[GreenV8S]

Read https://www.12voltplanet.co.uk/relay-guide.html and see whether you can identify the relay as either DIN 72552 type A or type B.

If it is one of these, identify which terminals the remaining wires are connected to. From that we can work out which wires are disconnected so we can tell how to identify them.

[Macski]

Hi and thanks for your reply, I some how missed this message and I will look up the relay tomorrow.

[Oldandslow]

Or post photos

[Macski]

Oldandslow said:

Or post photos

Red is connected to 80
Black to 85
Blue and yellow is loose

Edited by Macski on Sunday 19th May 12:27

[E-bmw]

Google "auto relay pin-out" you will get a pic like

https://www.google.co.uk/search?q=auto+relay+pin+o...

87/30 are your load (light) & 12v supply.

85/86 are your "controlling circuit" such as 12v + from switch one side & chassis the other.

[GreenV8S]

Macski said:

Red is connected to 80

Do you mean 30?

[Macski]

GreenV8S said:

Do you mean 30?

Yes, on closer look it is 30!

[GreenV8S]

I expect you'll find there is permanent 12V on red, and permanent ground on black. You should check that. If that's what you have then blue and yellow are the 12v signal to operate the relay, and the switched supply out to the load. You can see which is which by trying to turn it on and seeing which of these gets 12V on it - that needs to be connected to 86.

[Macski]

GreenV8S said:

I expect you'll find there is permanent 12V on red, and permanent ground on black. You should check that. If that's what you have then blue and yellow are the 12v signal to operate the relay, and the switched supply out to the load. You can see which is which by trying to turn it on and seeing which of these gets 12V on it - that needs to be connected to 86.

Lots of thanks for your reply!!!

How do I check a negative???

I have a gadget that can check live wires but ground?

[GreenV8S]

If it's grounded, there will be 12V difference between that and battery positive.

[Macski]

Thanks again

[Macski]

In need of more help!!!!

Reconnected the relay a few days ago all went well but the light still does not work as there is no live coming from the switch.

Been on you tube but still struggling to work out how to find the break. For 230V I have a gadget that will stop bleeping once the electricity stops, is there something like this for 12V systems. I seem to recall watching a you tube video on an attachment for a multi meter that will do this but maybe I was wishful thinking.

Thanks for advice.

[GreenV8S]

Either a volt meter or a simple test lamp would do, if you understand electrical circuits well enough to use them.

[Penelope Stopit]

The rear fog light switch supply cable will very likely be wired into a sidelight or headlight cable at the fusebox and possibly have an in-line fuse

[E-bmw]

^^^^ Wot they said, you need a test meter or test lamp, a wiring diagram & some time to work through it.

[Macski]

Penelope Stopit said:

The rear fog light switch supply cable will very likely be wired into a sidelight or headlight cable at the fusebox and possibly have an in-line fuse

E-bmw said:

^^^^ Wot they said, you need a test meter or test lamp, a wiring diagram & some time to work through it.

It does have an in line fuse but that is OK, the switch lights up so there is power there and therefore must be a break between the switch and the relay?

[E-bmw]

Macski said:

Penelope Stopit said:

The rear fog light switch supply cable will very likely be wired into a sidelight or headlight cable at the fusebox and possibly have an in-line fuse

E-bmw said:

^^^^ Wot they said, you need a test meter or test lamp, a wiring diagram & some time to work through it.

It does have an in line fuse but that is OK, the switch lights up so there is power there and therefore must be a break between the switch and the relay?

1, never assume anything.

2. Just because the light on the switch comes on, that doesn't mean the switch is ACTUALLY supplying power from it, it could be internally damaged.

Start at the switch, check 12v in/out then check wiring.

[Macski]

E-bmw said:

1, never assume anything.

2. Just because the light on the switch comes on, that doesn't mean the switch is ACTUALLY supplying power from it, it could be internally damaged.

Start at the switch, check 12v in/out then check wiring.

Thanks for pointing out how dumb I am, I never thought about checking the switch!!!

[Penelope Stopit]

Sometimes a person will wire the switch to switch a negative to the relay