Headlight Relay Issue

Technical Area Electrics & ICE
2

Heey Guys,

So I bought this Mk1 1991 MX5 around 2 weeks ago, I have been working on as much as I can, but having a bit of trouble with the headlights, when I first got the car, the previous owner unplugged the connectors just next to the headlights, due to him saying when he plugs them in, they go up and down constantly and wont stop until the battery dies. So upon getting this home, I tried plugging them in to make sure, and he was correct, that exact thing happened. First things first i was googling and looking at relays etc, and noticed I have 2 LA10’s, and a HD22 on the passenger side under the bonnet and thats it, no other connectors for any other relays, tried looking for the LA12 relay and couldn’t find this one at all. Couple days later looked under the drivers foot well and noticed a few relays under there, one being the “retractor relay”, so I took this out and replaced it with another that i purchased which I was told “works”, so plugged it in, and its great the switch in the dash now works, it moves them up and down, so it was a faulty retractor relay. However though the headlight switch on the stalk seems to mess it all up, when its off its fine, if I turn the sidelights or headlights on via the stalk, the headlights go straight down and turn on, once turned off they come straight back up, same goes for Hi beams/ Flashing someone.

So the things I have tried so far to fix the problem are as follows:

  • Tried 3 different retractor relays, 1 is faulty the other 2 supposedly work
  • Replaced the dashboard/tombstone switch with another one, which again apparently worked on another car
  • Bought another whole stalk setup, including windscreen wipers etc, and still same issue
  • Removed all grounds/earths across the car, grinded down the areas of where they sit, and replaced all the rusty bolts, shiny areas, and still nothing
It seems they are up all the time, and I can press the button on the dash which gets them to go down, however if I turn the lights on, they will come on okay but it stays down, and if I press the button on the dash again they still stay down, only until I turn off the lights will the come up and stay up. No custom wiring as far as im aware and can see, Fuses have been checked and are solid, the system works just only in reverse completely, and yes I have taken all the relays out, and power to motors, and swtiches and tried winding them down manually, but as soon as I plug them back in they go back up.

Might be some stuff I missed, but any help would be appreciated

3

How good are you with a wiring diagram and a multimeter? If the answer is sh*t hot then page 3 of this diagram may help.

http://www.mellens.net/mazda/Mazda-Miata-1991-1993/1991_wiring.pdf

Just to clarify the dash switch should leave the light permanently up when pushed in. When it’s out they should be controlled by the stalk. Are you saying that the lights don’t stay either up or down whichever position the dash switch is on?

Fill in this chart -

Dash switch position   Lights on/off   Light position

Out                          Off                 ?

Out                          On                  ?

In                            Off                  ?

In                            On                  ?

Up or down for the four options might make it easier to diagnose.

4

Thanks for the reply, I have had a very vague look at the diagram and kind of understand it, but when I get more time I will have another look.

Dash switch position   Lights on/off   Light position

Out                          Off                 ?                    Up

Out                          On                  ?                    Down

In                            Off                  ?                    Down

In                            On                  ?                    Down

 

It seems they are in stuck in reverse, if I press the button in on the dash it goes down, and unpress it then comes back up.

Funny thing is Iooking at the diagram it shows the headlight relay, and the coloured wires coming out are 4 different wires and one wire being red and blue, the diagram also shows there is meant to be x2 of these wires, but I have looked everywhere and cant seem to find this particular relay if it is different from the retractor one.

I have looked in the passenger side of bonnet and only 2 relays there which are LA10 and HD22, and on the drivers side under the bonnet is the fuse box which has LA10 and lots of fuses etc. Looked under the drivers footwell and I have the retractor relay which is labelled retrac and the grey flasher relay. Other than that the passenger footwell is empty and has no relays at all, so I have no idea what it could be.

5

Forgot to mention I can also use a multimeter if need be

6

Leave that with me, I’ll have another look at the diagram and see if I can work it out.

 

7

Warning. Before you TOUCH the headlight mechanisms and wiring disconnect both of the plugs to the mechanisms and check that they don’t move up or down in any combination of the dash retractor switch and light switch. If that mechanism moves when you have a finger in there you will lose it.

OK, I’ve looked over the diagram and your filled in table and also looked at your initial post.

However much I look I can’t come up with any fault situation that could cause this problem.

The problem the previous owner had was that they wouldn’t stay up. When they were supposed to go up they went up and down continuously. This would be due to a stuck ‘down’ contact on the retractor relay. Disconnecting the connectors next to the headlights would stop them moving but it wouldn’t be possible to stop them in the up position. What he should have done then was to use the winder mechanisms to wind them both up. What I suspect he may have done is to turn the cam mechanism 180 degrees or swapped some wires over.

First thing to do though is to check out the electrics. Using your multimeter on each headlight mechanism connector you should have the following readings.

DC voltage readings with negative lead to black earth wire -

Dash switch position   Lights on/off  Red/Yellow   White/Red

Out                          Off                   0v              12v

Out                          On                   12v             0v

In                            Off                   12v             0v

In                            On                   12v             0v

Assuming you are getting the correct readings here then either the mechanism (cam arm) has been moved 180 degrees or the Red/Yellow and White/Red wires have been swapped over in the connectors. Where the cam is bolted onto the motor shaft there should be a small white paint mark on the nut and cam to check that it is aligned correctly. If this has been disturbed then it’s the mechanism that has been tampered with. Don’t forget to disconnect the motor connector before you play with it.

Let me know how you get on.

 

8

Roadie is not kidding when he warns you to ensure there is NO chance of the motor running. I have seen this happen, fortunately there was only a screwdriver in the way and it was not easy to get it lose. The motor DOES NOT reverse, the opening and closing is done with the motor rotating in the same direction.

Sorry to repeat but having seen a near amputation I felt I had to.

9

Okay thanks for the heads up about the headlight mechanism guys, I kind of guessed it wasn’t safe originally so I always made sure I disconnected it haha.

 

Okay so I got those readings for you, and wasnt sure where you wanted me to get those readings from, so I removed the retrac relay and tried both those colour wires, and with the switch in or out, or with headlights on or off, i got no readings at all, none of them were 12V at all, and only one occasion gave me a reading, but was something like 0.00125, others were around 30 ish or completely dead. Which is serisouly weird as when i plug in the retrac relay the dashboard switch works fine regardless, so may be that im taking it from the wrong end, so let me know on that one, and where I should take the readings from.

So baring in mind I only just bought the vehicle, im currently in the middle of slowly servicing the car fully, and I was doing the fuel filter and noticed a cable just behind but next to the fuel filter, which looks like a ground cable, and ill be honest looks like a rat has chewed the cable and it has frayed, I had done all the grounds on the car apart from this one, so if it is this one, could this be the culprit? Does it link to the headlights possibly? As I say its under the car looks like its connecting to a underframe, and is very close to the fuel filter.

I tried looking at the cam arms, and ill be honest I have no idea if I am looking at the right thing or not, however couldn’t see the white mark you mentioned, but yeah might be because I was looking at the wrong thing, also noticed some black mastic stuff over one of the cables on the headlight motor, unsure if that is meant to be on there or not, if not then this may indicate some tampering.

 

Last but not least, when trying to get the meter readings for you, I had the retrac relay unplugged, (meaning the dash button would stop functioning) I turned on the headlights, and they stayed up (because of no retrac relay) however lights didnt come on at all, so I turned them off and turned it back on, waited around 3-5 secs and they slowly came on, but were very dim, and gradually lit up, now im 99% sure that is a grounding issue, but my point is, if that is a grounding issue, and ive done all the grounds apart from the one under the car, is it possible that headlight bulb grounding is linked to that as well as the retraction being in reverse?

Cheers for the help guys, much much appreciated  

10

You need all the relays and switches connected. Just disconnect the headlight motor connectors and take the readings on these connectors, loom connectors, not mechanism.

You can see the cam connected to the motor on this video. -

https://www.youtube.com/watch?v=CCHr0vk0hdI

 

11

Thank you so so so much for all your help, looked at that video, and then knew what I was looking at, however didn’t have any white markings, or at least there was a tiny remain left behind of it, however I had noticed that the mechanism was dirty, and someone recently had used a spanner or something to move the nut as there were marks in the dirt showing this. So all I did was reverse the mechanism, so the car thinks its correct, and is now showing as correct for me, I can now press the button in and they pop up, headlights work as they should now and come up when turned on via the stalk, so all is groovy.

 

Once again thank you for everything, you truly are a star 

12

You’re welcome. I’m a retired BT engineer so pouring over a wiring diagram keeps the old grey cells working.

You haven’t fooled the car into thinking it’s right. You’ve put it back to how it should be.

This is all down to the previous owner not having a clue. If he had just googled it he would have found out it was almost certainly the retractor relay. Unplugging the mechanisms was fine as a work around but then he should have just wound them up using the manual controls, that’s what they are there for. The term RTFM springs to mind! I’m referring to the previous owner not you.

Not many problems that the good folks on this forum can’t help you with. I’m no experts on the mechanical bits but I do like an electrical puzzle.

Thanks for coming back and reporting that the problem is sorted. Many don’t. If you could press the thank button on one of my posts that would be appreciated.

What this does all show is that the previous owner has been cocking about with stuff that’s beyond his capabilities. Well worth going over the car with a fine tooth comb to make sure everything is OK. Don’t want to find out that he’s screwed something like brakes, steering or suspension up.

 P.S. Put your location in your profile. Helps to find local members if you need any help and for recommendations of trusted local specialists and services.

 

13

Haha that makes a lot of sense, still in the process of checking it all over etc, got a lot of new parts ready to go on, major one for me will be the cambelt kit so you may see me post again if I get stuck with this haha, other than that it was just the headlights, which im glad are now done. 

 

I will defo press that thank you button, and thank you for the tip below as well.

 

Many thanks again 

14

Did anyone answer the question about where the headlight relay is?
I have spent all afternoon trying to find this in my 91 Eunos and can’t locate it!
Cheers

15

I eventually found mine hidden under the drivers side foot well, it was a black relay and does say headlight relay on it, more located on the right under the foot well.

How this helps!

Let me know how it goes.

16

I’ll have another look today. More acrobatics!
Thanks

17

Hi. I did find the headlight relay in my Eunos today. I had my wife operate the stalk and then hunted around until I found the clicking relay. It is located in the engine compartment on the LHS wing. My relay is marked:
LA12
DC 12V 10A
TR. IMASEN
OK16

I was able to confirm today that the PAS switch (headlight flasher) does bypass this relay, so if faulty will cause the headlights to come up - even if the relay is absent!

18

Nope - I’m wrong (shit)! That’s the retractor relay. I found a diagram (https://static.cargurus.com/images/site/2016/04/08/06/14/pic-7828951806837196461-1600x1200.jpeg?_ga=2.141611253.613835740.1586629272-1785732002.1586629272) that suggests that the headlight relay is a H300 (30A) type. This has a completely different base, of course.
I still can’t find this!
I looked in both footwells but it is not there. Sigh
Any further ideas?

19

Great stuff!

Forgot to mention earlier that it does depend on which car you have, I have a japanese import RHD eunos and mine was under driver side, I believe the american version or proper UK one has a blue relay labelled LA12 as you have found, however i may be getting mixed up with the countries, but nice work for finding it!