HELP with wiring in a Mk 2.5 double fog light switch into a Mk 2?please***SOLVED***

Technical Area Electrics & ICE
21

OK, so I arrived back this weekend and had a stab at sorting out the wiring today for my fogs using this switch. My first task will be to get the switch with the light working.

Going by the wiring diagram above (I’ve edited the post as one of the wire colours was wrong - Green/Yellow as opposed to Grey/Yellow) I connected up the illumination and this was successful - the pictures on the switches now light up with the lights on.

Now I’m wondering where the live 12v input goes. On a standard Mazda fog switch, this is the same input which lights the lamp on the switch, so I connected this to pin 3 and then connected my front fogs up to pin 5.

What happened? Well, when the lights are turned on, the light on the fog switch illuminates green no matter if the switch is on or off. The fogs do not come on whatever the switch state.

Questions: can someone who has this double switch in their Mark 2.5 tell me if the green light should be on when the switch is off; does it turn red when on; or does it turn green only when switched on.

Also, can anyone shed any light on what I may be doing wrong?

Thanks everyone,

Gareth

22

It lights up green when the fog lights are on, off when the lights are off.

Can’t help with the wiring questions, sorry.

 

23

Thanks Andy, so I am now wondering how on earth this switch works!

If the light only comes on when the switch is ‘on’ then there must only be current in the green/yellow wire when the switch is ‘on’ otherwise it would be on all the time, as I have discovered. This must come from the front fog relay. I’m wondering how the rest of the switch works. My multimeter is out of batteries, I’ll try and get a new one this afternoon and test the switch tonight.

Gareth

24

OK, so after fiddling around with a
multimeter this evening, I have some success (or at least it appears that way!)

<o:p> </o:p>

First off, the pin layout:

<o:p> </o:p>

1 _ _ _ _ 2<o:p></o:p>

3 4 5 6 7 8<o:p></o:p>

<o:p> </o:p>

These correspond to the following Mk2.5
wire colours: <o:p></o:p>

 

  1.  Grey/Red
  2.  Red/Black
  3.  Green/Yellow
  4.  Black
  5.  Blue
  6.  Yellow/Red
  7.  Black
  8.  Unused
 

Numbers 1 and 2 are obvious: these wire
colours are the illumination for the switch, as with all other switches. These
are tested and these work, lighting up a nice shade of orange. The remaining
five pins must be for the following functions: Earth, front fog, rear fog, 12v.
Being as how there are only four, there must be two earth or two 12v, or
something I am completely missing

<o:p> </o:p>

Next, I tackled the pins with a multimeter.
 When the light-up switch is ‘off’, there is a permanent connection
between pins 3 and 4 with a slight resistance between them. There are no other
connections. When this switch is ‘on’, there remains this connection, and there
is also now a connection between pins 3 and 5 (similar resistance) and pins 4
and 5 (no resistance). So this must be the switch and its ‘on’ light.

<o:p> </o:p>

Thinking about this logically, the pins
between the ‘on’ light must create a resistance due to lighting the diode, with
the 12v straight to the fog relay having no resistance. Also, as pin 5 has no
connection when ‘off’, this can only be 12v. Since 4 - 5 is the only connection
with zero resistance, pin 4 must be out to the fog relay. This means 3 must be
earth.

<o:p> </o:p>

So, we now have:

<o:p>  </o:p>

  1.  Grey/Red: illumination
  2.  Red/Black: illumination
  3.  Green/Yellow: Earth
  4.  Black: front fog 
  5.  Blue: 12v
 

Connected up, this works, although I did
first think I might have this wrong and presumed that black must be earth -
this caused smoke to come out of the switch. Still seems to work,
though!

<o:p> </o:p>

Next, I took a look at the other pins… 6
and 7. When the rear fog switch is held in (otherwise it springs back out)
there is a connection between pin 6 and 7. This would mean that these two could
be 12v and rear fog. So this would be:

<o:p> </o:p>

6. Yellow/Red:
12v

7. Black: Rear
fog

<o:p> </o:p>

So, when all this was wired up… it
worked! Assuming this wiring is correct (and I am NOT
guaranteeing it is and won’t melt and burn your car down!), the front fogs
are fine; all that remains is to make the second switch work with the rear fogs
and light the foglight light in the instrument cluster.

<o:p> </o:p>

The rear fog switch on a Mk2.0 is different
to this switch… it rocks left and right, as indicated by Mark above, so
splicing the wires in this switch to the wires from your current switch will
not work as the relay must be different - momentary current down one
wire for ‘on’ and down the other wire for ‘off’ on the Mk2.0 as opposed to a
momentary current down the same wire for ‘on’ and then another down the same
wire for ‘off’ on the 2.5.

<o:p> </o:p>

Now this is where I am out of my depth.
According to Wikipedia, latching relays should solve this problem (http://en.wikipedia.org/wiki/Relay#Latching_relay):

<o:p> </o:p>

A latching relay has two relaxed states (bistable).
These are also called ‘keep’ or ‘stay’ relays. When the current is switched
off, the relay remains in its last state. This is achieved with a solenoid operating a
ratchet and cam mechanism, or by having two opposing coils with an over-center
spring or permanent magnet to hold the armature and contacts in position while
the coil is relaxed, or with a remnant core. In the ratchet and cam example,
the first pulse to the coil turns the relay on and the second pulse turns it
off. In the two coil example, a pulse to one coil turns the relay on and a
pulse to the opposite coil turns the relay off. This type of relay has the
advantage that it consumes power only for an instant, while it is being
switched, and it retains its last setting across a power outage.<o:p></o:p>

<o:p> </o:p>

So, it would seem that this type of switch
would need a ‘ratchet and cam’, single coil relay. I have no idea what the
wiring for this looks like and can’t seem to find this online. I am
guessing it would have an input - this would be the rear fog wire -
and an output for this (these two would activate the coil), it would
then also need a 12v for the coil and an output which would continue to the
rear fog. This output would split and head to the instrument cluster also to
activate the foglight light.

<o:p> </o:p>

Does anyone have any experience here and be
able to offer some help?

<o:p> </o:p>

Thanks,

<o:p> </o:p>

Gareth

 

 

25

More progress.

So, after many phone calls and visits to Maplins, Halfords and half a dozen autoparts shops, I think I have found what is needed in a small car electrical specialist in Wimbledon - this guys knows his stuff.

When I explained what I needed, he paused and thought for a second or two and said I could probably find what I needed on a 70s VW Beetle! Apparently the main beam/dipped beam switch worked just like this - momentary current in the connection for main beam, momentary current in the same connection for dipped. Awesome knowledge; this relay should be just what I was looking for! 

There’s a VW parts shop over in Woolwich - I’ll go over and pick up the part tomorrow and see if I can’t get this working. Here’s a picture of what I think is the part:

Latching relay

I don’t understand the diagram - sort of hoping the shop does [:D] Can anyone shed any light? I’ve made it clearer to see below:

Relay wiring diagram

Gareth

26

OK, so I’ve got my relay and it’s slightly different from the one above:

vw mx5 fog relay

The guy in the shop knows nothing about how they work and I can’t really figure out what is going on in the top right; it looks as though 56a and 56b are touching.

Does anyone understand how this relay works?

Gareth

27

 

Hi gareth

I’ve kept very quiet on this one as I really should be able to reel off the answer, however I haven’t worked with this sort of relay stuff since 1972, so I’m a bit rusty

I came across this in the archives

They have the following terminals:


#30 - 12v+ constant (30A)


#56 - 12v+ switched


#56a - output #1


#56b - output #2


#S - toggle ground (-)




This latching relay is meant to be a headlight dimmer relay to switch
between hi/lo beams. It is capable of carrying the current for two
standard sealed beam headlights (60W x2).




#30 is the primary connection and where the current to power the headlights is drawn from.



#56 is used as a “safety”. Unless #56 is connected to 12v+, current
will not flow to the outputs. This low amp draw usually comes from the
headlight switch.


#30 & #56 can be bridged together to simplify wiring. I’m not sure if the relay will work properly if #30 is not powered.




#S is momentarily grounded to switch between output

#1 & #2. While it is grounded, #30 is momentarily connected to
both outputs. This allows a “flash” of lights when the headlights are
off.



The selection of output #1 or #2 is mechanical. The output selected
will remain until changed. Even if power to both #30 and #56 is lost.

Hope it helps

28

Thanks Geoff, I really appreciate any help! Looking at the diagram, do you think that when the relay is being used, there is only either power at 56a or 56b - or is there some form of power at both for each state?

I’m more than confused by the way the terminals in the top right look to be connected together…

Thanks,

Gareth

29

 Hi garath

The relay you have looks nothing like the one i have been told to buy from my auto spark friend???

I’m not up to speed on the adding a picture to show you,but i’m sure someone will let me know soon "please"in easy english???

Many thanks

Wayne

One Stop Mx-5 Roadsters

Manchester

30

 Just a thought,but is it worth getting hold of the relays from off a Mk 2.5 sports???

Wayne

Manchester

31
Register an account with an online picture library (I use PhotoBucket.com). Upload your picture and click on ‘share’ (in PhotoBucket) and copy the text from ‘Direct link for layout pages’. Then when posting your message in these forums, click the little picture of the tree and paste the text you copied into the 'Image URL' field.

Gareth

32

If you can find out which one it is, this would be another solution, possibly better! I spoke with Mazda on the phone and the guy didn’t sound like he knew for sure which one it was. He said there were a bunch of relays in that area - heated rear window, heated seats, etc, and they were all the same. Without seeing the wiring diagrams, I wouldn’t want to take the gamble!

Maybe give your local Mazda dealer a ring and see if you can fare any better. Roadster Robbie told me it was called the “Rear fog light control unit”.

Gareth

33

 Hi Gareth

Me and an engineer friend  of mine(paul) took this bloody switch apart today to find out the difference inside between the two sides??? a small piece of paper clip type wire which acts like a spring come lock on the press on and then press off side and thats it, my friend has taken it home with him to make this little bit of metal so both sides will become press on and then press off,we tested all the wires for continuity tests so as soon as he brings it back(this weekend) I will have a go at wiring it in???.

Oh by the way i phoned two mazda franchises to name and shame mazda stockport and mazda warrington has much use as a fart in a astronaut suite,my faith in dealers still remains at an all time low.

I’ll let you know how i get on>

Wayne

One Stop Mx-5 Roadsters

Manchster

  

34

 Wayne,

I have a 2003 electrical sheet detailing the fog light switch/relay connections if you want a copy? - see here http://www.mediafire.com/?wdzonmt4za2

Eric

35

 Hi Eric

Thank you very much, that will help.

Wayne

One Stop Mx-5 Roadsters

Manchester

UK

36

Hi Eric - could you PM me those diagrams also? This would be an awesome help!

 

Edit: sorry, just saw the link in your post :slight_smile:

Thanks,

Gareth

37

 Downloaded and printed out - these are fantastic - and in colour too! These are awesome, Eric. Thanks.

Unfortuantely, Wayne, these are US wiring diagrams so will not have the info for our switch. The fog light swtich on these plans is a standard three pin switch as the US cars do not come with rear fogs.

If anyone knows of a link to a PDF of the UK wiring diagrams, that would be awesome!

Eric - I still thank you again for these as most of the stuff is similar and this will help me immensely on some more of my Mk2.5 into a Mk1 projects, next stop the Instrument Cluster!

Gareth

38

Hi All

I have had a number of e-mails from members on here and beyond for the answer to this problem so i think i should post this,sorry it’s taken so long to do??? 

To anyone who needs to know how to get this bloody switch working here is how>>>>

first carefully take the switch apart being very carefull not to loose anything???and remember where everything goes.

The side that latchs Re:-press on,and press off side look inside and you will find a little spring on the switch itself,i used one from an old vcr,but anything similer will do,now the lacthing mech, carefully remove it and make a copy of it for the other side,  i  used a paper clip(but anything similar will do)you will need to make a new tiny hole for the new latch spring you have made,just copy the other side.

Put both springs back in,put the switch back together and you now have a double switch you can use and it’s as simple as that>

Hope this helps others at some point

Sometimes the simplest solutions work out best.

Very kind regards 

39

 I know this an old post but i have the switch and i have strpped it down.

I have already strpped down 2 vcr’s and cant find a suitable spring from either of them.

Anyone know where i can buy the springs from???

40

 You will just need to find some out of a kids broken toy etc, anything, maybe i was lucky with the one i had to take apart,you cannot buy them.?

M-m