Eduardo Santos

Hello everybody.
I need to know what do you think about this relay, in what respects to it's funcionality (because I don't know what it does) and it's state (because it seems to me kind of burned or something...). It's from a 1987 Mazda RX-7 FC NA.
Here are the pictures:















Help appreciated.

gracer7-rx7

iTrader: (16)

The relay itself doesn't look too terrible but what it plugs into looks pretty bad. That part definitely needs to be cleaned up with a wire brush to make good contact.

Gasso

Can you tell what color wires are on the connector? I would think you could look through the wiring diagrams and find the 4 pin relay connectors. Then it's just a matter of matching the color of wires that are on the connector to the illustrations in the diagrams.

+1 for cleaning. Cleaning the terminals in the connector seems like a pain... might be able to replace with new ones.

Eduardo Santos

Thanks guys for your good advices. I'll see what I can do and report back

Eduardo Santos

So, I have cleaned the contacts with a tool that I have, and now the contacts look like this:









So, much better, heh?

And guess what, after I've cleaned them, my car's headlights (which weren't giving any light at all), started to give good light
I never actually believed that just by cleaning them, they would start working. But they did! And that's awesome!

Gasso: The wires that the connector has, are: 2 red wires, 1 white with a blue line and 1 red with a green line. It seems that this connects to the car's headlights, since they weren't working (they didn't give any light, although they did went up and down) and now, since I cleaned them, they do give light.

Thank you very much for your help.

RobbyWally

iTrader: (2)

It is, indeed, the main headlight relay. The poor physical / electrical contact caused resistance heating at the connector...got hot enough to melt and burn some of the plastic.

Nice work to get the contacts cleaned up.

The two red wires are incoming 12v; one to the relay coil the other to the NO contact. White/blue is the other side of the coil & goes on to the dimmer switch and light switch in the cluster switch. Red/green goes to the dimmer relay (coil and contact). Output of the dimmer relay goes to the headlights.

Lmill86

iTrader: (10)

You might have to get a replacement. It looks like it could cause some future problems.

Eduardo Santos

A replacement of what? The connector?

RobbyWally

iTrader: (2)

He's probably talking about the female connector where the plastic is melted / burned away between two of the connectors.

Eduardo Santos

Yes, he probably is. But where would I get such a thing? The dealer here in Portugal sucks, and it's reply to almost all my requests is: "we don't have that part for that car anymore..."

day341

I would also check all of the connections for those wires, a bad ground could also cause the melting. Check the fuse for that circuit too and make sure its not higher than the rated fuse that it should have.

Eduardo Santos

Yeah, I'm going to check those wires, yes. The fuses should be alright because I checked all of them on the engine bay, and on the cockpit (near the driver's feet) like 1 month after I bought the car... There were a lot of them that were switched, and some were with ratings different from those specified by the maker. They are all correct now.

RobbyWally

iTrader: (2)

That size plug with 4 female connectors is pretty common...both in RX-7s and in general. You might be able to find one on your car that is not in use (like a check connector or as pre-wiring for an option your car does not have). And, you local auto parts place...if you have one...might have one. Take the relay in & see if they have something that fits.

BTW, as you are checking / cleaning other connectors, it is possible to release the brass connectors (both male & female) from the plastic plug to make cleaning easier. The male spades are a lot easier, but both are possible. There also are chemical sprays (Deoxit) that remove the oxidization layer. I've experimented with soaking connectors in dilute acid solutions, too (vinegar = acetic acid and swimming pool stain remover = ascorbic acid). Both seem to 'loosen' the oxide to make it easier to remove. Then I soak in water and dry with a heat gun.

Eduardo Santos

That's seems to be a good advice. I'll see if any store here has that. I hope they do, because they usually tell me they don't have, everytime I go there with a small part...

How do you release the female brass connectors?

RobbyWally

iTrader: (2)

Not all plugs are the same. Some have a plastic tab to retain the brass part while on others there is a small tab on the brass part. I have used various thin but relatively rigid probes that I slide into the plug. A strip cut from an old credit card ~ 2 mm wide works sometimes. Best (but not easy) is to examine the plug or one like it to figure out how the brass parts are retained.

I have a spare engine harness that I've been using as a learning aid. Will try to get some pics for you.

Eduardo Santos

I think I got the explanation, but if you could get some pictures that would be awesome. It would prevent me from making a mess...

Gasso

Awesome work! Sorry I didn't get back to respond about the wire colors. Was going to guess headlight relay on earlier post but I wasn't sure so I didn't throw it out there... I need to get another 7 so I can be more useful . Keep up the good work Eduardo

Eduardo Santos

Well, your guess was right
Thank you for your support

RobbyWally

iTrader: (2)

This evening I removed the wires from a 4-connector plug in my 'spare' harness. It is the connector for the boost sensor but identical to your headlight relay. Once I understood the shape of the plastic retaining tab, it was pretty easy. And so much easier to clean up the connectors.

I'll get some close-up pics of the tabs at work tomorrow.

Eduardo Santos

Thanks man.

RobbyWally

iTrader: (2)

2 pics are from the connector side and wire side for one connector of a 4-connector female plug - same config as your headlight relay connector. The focus is on the plastic tab that locks the brass connector in. As the connector is inserted from the wire side, the tab lifts out of the way and then drops back down behind the curved parts of the female connector.

Once you see what the tab looks like & where it is, it's quick and easy to lift the tab with a tweezer or jeweler's screwdriver so that the connector can be removed from the wire side. And then easier to clean the connector.

Typical precautions...never do this with a circuit that is engergized or might become energized. Best practice - disconnect the battery. [I was working with a connector on a harness that isn't in a car.] And, always take a picture or make a sketch & label which wires go in which location.

After removing the 4 connectors, I soaked the connectors for about 5 minutes in a mild solution of swimming pool metal stain remover (ascorbic acid) to dissolve away the oxidation. Then wire-brushed, rinsed in water, shook off excess water & dried with a blow dryer.

For your case, where the plug partition is melted, if you can't find a replacement plug, I would advise trying to find one somewhere else in the car that is a non-critical or low power system & swap the two plugs. All the current for both headlamps has to flow through the two connectors where the partiton is gone.

Hope this helps.

Eduardo Santos

Oh, now I get it. Great pictures man, with ilustrations and everything
Thanks a lot. Next time it will be easier for me with those tips

RobbyWally

iTrader: (2)

Thanks. So many tech issues with our older cars come down to degraged electrical connections. I am planning to build up a library of connector configurations and a how-to for cleaning. This is a start.

Eduardo Santos

Yeah, it's normal if we think how old they are.

That's sounds like a very good idea.