Indicator fault mystery... MK2 (98)

Technical Area Electrics & ICE
2

This maybe one for the electrical gurus

 

The problem only occurs in winter (for the past few years) and is basically the right hand side indicators (x3) stick on, and stay on even if the stalk is returned to centre and even occasionally when the ignition is turned off to try to reset them!  The left hand side ones work, even when the right hand side ones are stuck on.

Clues:

  • I've replaced the flasher unit last spring with an OEM one but the problem has come back this winter
  • The problem is intermittent (like all good mysteries...) and sometimes the right hand side ones work normally, and sometimes they flash faster than normal, but mostly they stick on
  • Sometimes the flasher resets when the ignition is switched off, but sometimes all three lights stay on when the ignition is turned off.  I then have to take the IGN fuse out (under the bonnet) for the lights to go out
  • When the RH side indicators are swiched on the flasher clicks once to turn the lights on then sticks, it works fine clicking away when the left hand side indicators are switched on
  • The flasher never fails off, it always sticks with the lights on
  • When they are stuck on with ignition turned off, I can remove the front bulb inside the headlight unit, but the other two remain stuck on - I don't know how to remove the side repeater bulb on the front wing to see if the rear one stays on, I haven't tried just removing the rear bulb yet
  • If I turn the Hazards on, both sides stick on.  Hazrds work fine in the summer when the RH indicators are working OK
  • The bulbs are all standard fitment and haven't been replaced in the 10 years I've had the car
  • When the weather warms up they work fine throught the summer/autumn
Any guidances gladly welcome

 

 

 

3

Earthing fault.

Happy hunting!

4

I agree sounds like an earth, seek them out and clean them up

5

Before hunting for the earth fault maybe take out & clean the contacts on the relevant fuses & the fuse holders ?

 

Always try the easy solution first IMO

6

If this helps - http://www.mellens.net/mazda/mazda_miata_extra_manual/1999_wiring.pdf
Scroll down till you get to Exterior lights. (Always at the bottom of the page.) Unless you can print this, it’s difficult to view on screen, but if you know how, click on the settings symbol - three vertical dots at top right of the page, beneath the red exit button, and click on the Zoom + sign till you can read clearly each letter and word. (don’t hit the red button - you’ll lose the website!)

Staring at the top, you will see two fuses are involved, both in the lower dash fuse box - The Hazard and turn signal fuse - both 10 amp.bear in mind the diagram is for a Miata, (left hand drive) so all locations are opposite in a UK car. Conveniently, all positive sources are identified, e.g. the hazard is permanently live and the turn signal is only live when the ignition is on. Follow both fuses down to the hazard switch, and (ignoring the switch outline box) the path of each part of the circuit is plain enough. In either hazard or turn position, the positive appears to be connected to the flasher unit, which in turn operates to ground (G202) and should flash in either operating mode. At a guess, the unit operates once only (switching turn lights or hazard lights on) but stays on, as the ground path seems to be faulty. - The ground is right hand side of the dash - underneath of course! This is illogical, as you say it operates fine for a left turn, but not for a right or emergency flash. Also only happens come winter time.

As the flasher unit needs a permanent ground, then it looks like the ground is intermittent or high resistance (bad connection) but sufficient to cause the internal contact to close, but it remains closed as there is insufficient current flow to cause it to keep operating. My logic says this should be the case in any mode, left or right turn, but you say Not so. Frankly - no idea why this is the case, but try cleaning ip the ground connection first - and see what the result is. As I’ve said many times - I hate blank boxes, so no idea if the flasher unit is solid state or a traditional flasher unit, not that it matters, that’s incidental to the problem. It works on left turns!

My only other thought (prompted by years of experience) is that someone has modded the wiring in some manner, e.g. - added a new radio or additional equipment, which has been connected to the indicator circuit
in error and may be the cause of the problem (backfeed, we call it) Such being the case, I can’t help further, you need to check this isn’t so. Have you got a multi-meter? - always a big help help chasing faults.

PM me if you still have problems. HTH.

7

Can’t see this being a fuse or an earthing fault. If the right side indicators are staying on ,either the flasher relay is faulty or there is a short circuit in the wiring allowing power to travel to the right side indicator circuit from an ignition source,by-passing the relay and switch. Any evidence of a previous add-on alarm system?

8

I tend to agree with this. 

As a starting point I would look at the switch, specifically for metallic dust from worn contacts shorting it into the On position. Cleaning it out might fix it.

The relay has transistors inside operating the timers and does not need much current to trigger it.  A bit of condensation might be enough to complete the circuit.

I’ve had similar problems with frequently used switches on other old cars, usually on the Dip/Main switch.

9

I agree with missfire. Has it got, or at some time had, an alarm fitted that flashed the indicators when activated/deactivated? If so this may be the problem.
If not then that’s a doozy of a fault.

The only thing I can think of which would be effected by temperature would be a bad solder joint or cracked pcb track that contracts as it gets colder but can’t see that being the case here as the only solder joints and pcb track I can think of would be inside the flasher control unit, and you’ve already replaced that, unless, as above it’s in the alarm system.
Good luck and I shall watch this thread with interest.
D

10

Thanks for all the replies guys (and girls?).

There was an alarm fitted/removed before I got the car, but as I said I’ve had it 10 years and only got this flasher problem the last 2 or 3, so if it is ‘connected’ to the old alarm circuit, I guess it’s more likely to be a loose connection somewhere, rather than something fundemental. God knows how I can trace that though, not knowing how/where the alarm was fitted. The key fob transponder still works OK as the dash key symbol light goes out a second or so after switching the ignition on allowing it to start up.

Is there a diagram (as in a photo etc. not a wiring diagram) anywhere that shows where the earth(ground) points are that might be associated with the right side indicators only?

Cheers

11

Clearly not then…

Could the biggest clue be that the right hand indicators stay stuck on (sometimes…) even when the stalk is centered and ignition key is removed? According to the wiring diagram the only ‘hot’ circuit is the hazard switch, could this be where the feed is coming from to keep the lights on when the ign is off?

As mentioned when the RH side is switched on via the stalk, the flasher unit just clicks the once to turn the lights on, then freezes. Are there two independant flasher circuits within the unit?

12

Clearly not then…

Could the biggest clue be that the right hand indicators stay stuck on (sometimes…) even when the stalk is centered and ignition key is removed? According to the wiring diagram the only ‘hot’ circuit is the hazard switch, could this be where the feed is coming from to keep the lights on when the ign is off?

As mentioned when the RH side is switched on via the stalk, the flasher unit just clicks the once to turn the lights on, then freezes. Are there two independant flasher circuits within the unit?

13

Yep,the flasher unit on these is a tandem relay device.One relay for left circuit, and one for the right.

14

Cheers bud,

Anyone know whether there are any cheapy repro units avaiable for me to test to check if my unit is bad, I don’t want to pay £40 for an OEM one in case it’s summat else?

15

Have you checked the indicator switch assembly? I’d suspect that before relays.

16

Do you have to remove steering wheel/airbag to get to the switch?

17

Frankly - you are chasing suggestions that aren’t relevant, the flasher switch is NOT causing the problem. If it were faulty in any way then it would be obvious. If it made momentary contact then the flasher wouldn’t work, and if there were a short circuit then the flashers would be on all the time. Head scratching and chasing proverbial rainbows won’t lead to a solution, what you really need is to find a local auto electrician who can sort it out for you.

As you describe all the symptoms above, then it’s clear that there’s a permanent positive feed floating around somewhere that’s causing the problem, and you need expert help to find it and isolate it, which is the only way you’ll solve it eventually. - What you haven’t clarified is to state what exactly happens, you say the right turn flashers are on all the time, but stay lit (no flash), or still flash?

To the best of my knowledge there are NOT two flasher relays, the circuit is common to all Mk’s and there’s no logical reason why Mazda would vary it. If you need verification of that then contact Roadster Robbie, who is sadly, only available now when he posts a reply, so PM him when he does that. Alternatively you can search through all the circuits that Mellens produce for most Mk’s and you will see there is only one relay involved,.