Aftermarket fog lights not working. Maybe relay

[TobyQuest]

Proud owner has had some nice yellow spot lamps added to the front but driving through 1 foot high flooding the relay for them was underwater.

With the multi meter ive found power going to the fogs etc but they don't turn on because power is not going to my fog light switch on the dash.

I've taken the realist apart and it did look a bit corroded. Anyone know how to fix a relay?

Ideally where could I buy a replacement of the same type ie. The one are the same size and direction and it does what it's supposed to do.
I don't know how they work.

By the way I've tested the bulbs etc and when I press the relay pin on manually they do light up.

Cheers

 

[TobyQuest]

That should say "previous" owner although I'm sure he was proud too hehe

 

[Richard n Ann]

You need a new relay, not worth messing about cleaning it up.

https://rover.ebay.com/rover/1/710-...0001&campid=5338547443&icep_item=123230291654

This is a 5 pin SPDT type so one connection wouldn't be used

 

[pj650]

I would think a good auto electrician will be able to match it with an equivalent one.
He would certainly know where to obtain one.If. It it’s been wet it would be better to
replace it than try to repair it.

 

[TobyQuest]

That relay has the pins at right angles to each other. Mine in the pic are all parallel to each other.

I don't want to take it to an auto electrician because it would be at least 30 quid minimum plus fuel plus the relay I imagine but if I can get the right relay and plug it on its a fiver and i don't know any auto electrician.

If I can't find the relay I could use the existing switch but then I wonder about the downsides of that. What does a fog light relay do that the switch on its own doesn't do?

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[pappajohn]

What does a fog light relay do that the switch on its own doesn't do?

The current required for the lights will be higher than the switch can cope with so the switch controls the relay on thin wire and the lights from relay are on heavier cables.
If you omit the relay the switch and wiring could melt.
Go on, ask how I know.... But I didn't know better back then.

 

[TobyQuest]

I've seen a 4 pin 40amp relay. It's there any problem using a 40amp one rather than a 25amp one?

 

[TobyQuest]

The current required for the lights will be higher than the switch can cope with so the switch controls the relay on thin wire and the lights from relay are on heavier cables.
If you omit the relay the switch and wiring could melt.
Go on, ask how I know.... But I didn't know better back then.

An good. I was thinking that. So if I don't find the relay I could replace the wire to and from the switch with thicker 25a wire as a solution?

 

[tacr2man]

I've seen a 4 pin 40amp relay. It's there any problem using a 40amp one rather than a 25amp one?

no prob

Some times fog lights are wired so side lights have to be on before they will work .

 

[TobyQuest]

If 40A works in place of a 25A then this looks like the right size. Hopefully fits my yellow plug shown above.

On the relay diagram here does it mean that number 1 is in the bottom right position and number 2 is in the top right position?

Also does the picture on the right side of the diagram mean that i would wire the switch up to the 2 contacts on the left and the live power and wire to the fog lights on the right?

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[autorouter]

40A relay in place of 25A should be fine. If you look straight on at the pins, there is a rectangular step in the plastic, which ensures it only goes one way into the plug.

Now look at the diagram. You can see the rectangular step. With the step at the top, 1 is lower right, 2 is upper right.

You can double check by putting 12V (+ and -) across what you think is 1 and 2. You should hear a click. Any other pin combination will give no click. There's no built-in diode, so no flash and smoke either.

The switch goes to 1 & 2. The fog light power goes to 3 & 4.

(This check is no good for a 5-pin relay, Two of the pins are connected when not powered)

 

[TobyQuest]

Cheers. Ive ordered the relay. Will make an update once its arrived

 

[TobyQuest]

I need a bit of help wiring up this relay. Ive tried just plugging it in to my existing plug. The plug fits, but the fog lights still dont turn on.

On my plug I have 4 wires.
Yellow wire and a white wire that go from the relay to the fog light switch inside. They arent connected to any power and theres a black earth wire thats grounded on a screw on the dashboard from the switch also

Then the other 2 wires are thicker ones, one red and 2 blue. The red one is live....the only live of the 4 wires and the blue one ones just go to the fogs.

So my question is, on the numbers shown on this relay above, which wire goes to each number, 1,2,3 4?

 

[Richard n Ann]

1 & 2 are the relay coil so on those go the wire from the switch and ground
It should be wired so the dashboard switch energises the relay. You can test this before connecting any of the other wires. You should hear the relay click. (you might need the ignition on)

Next 3 & 4 are the relay's switch contacts so there will be 2 thick blue wires together (in parallel) going to the fog lights and on the other side the thick red positive from the fuse box.

 

[Richard n Ann]

The yellow or white should be a ground ie joined to the black at the switch end.

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[gus-lopez]

The yellow or white should be a ground ie joined to the black at the switch end.

But one of those should also have 12v on it as otherwise there is no power to operate the relay ?

 

[Richard n Ann]

But one of those should also have 12v on it as otherwise there is no power to operate the relay ?

Yes the other one (yellow or white) will have 12v from the switch.

 

[Richard n Ann]

So... Yellow & white 1 & 2

Thick red on 3 and the two thick blues on 4

 

[TheBig1]

if white goes via the switch to the black, which is grounded, the yellow needs a positive supply. Likely a blown fuse because the relay shorted out

 

[Richard n Ann]

I'm thinking the switch will have a positive supply on it, and will switch it through to the yellow (or white )

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[TobyQuest]

Boom! Fixed.
So it turns out there was a lot of corrosion, im not sure which was the culprit but there was a 5th wire going off and spliced to the indicator bulb, that looked correded, the plug terminals were corroded so i cut them all off, put on new terminals and connected it to the new relay and done
Now ive mounted the new relay higher up on the van because the old one was on the bottom of the buper mount and went underwater in heavy flooding.

Thanks for all your help