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MG MGB Technical - The Flasher

Flasher questions & problems. Where is the "hazard" flasher unit located on my 71B? It doesn't work and I can't find it!

Also, could this be related or not? Turn indicators work fine UNLESS the headlamps are on. Headlamps on: no right turn indicator, no right high beam headlamp. The turn indicator on the dash stays lit....won't flash. Headlamp and parking wiring appear correct. Lamps swapped, same problem. Left side, OK.

Suggestions? Thanks for your help. Jerseyboy.
John

Check the wire connectors. In my '67 the light wires extend to the middle of the grille. They then double up with 1 set going left and the other right. Clean and jiggle and the lights may start working again. Once the lights turn on the switch in the flasher will start to work again.

I replaced the old flasher with a new electronic one that will flash at the same speed with any kind - or no bulbs -. The disadvantage, of course is that you aren't put on notice if a bulb or wiring has failed.

Barry
Barry Parkinson

Thanks Barry, but I just cleaned out extranious wiring from the front valance. My guess is the PO was doing fog lights, or something. I disconnected and reconnected everything with diaelectric grease after removing the "extra" wire. Everything looks good according to wiring diagrams, etc.
Thanks, Jerseyboy
John

The Hazard Flasher is inside the dash center
panel - next to the flashing Hazard Light indicator
(...or next to the cigarette lighter).

You'll need to remove the radio to access it.
Daniel Wong

Hi all.

I suspect that you have a high resistance earth on the right hand side lights.

The hazard switch itself could be the cause of your hazard probs.

Don
Don

John,

Check out the ground on that right-front turn signal. If the ground is open, remember that dual-filament bulbs have a shared ground inside them. If the current doesn't find a ground where it should be, it will start looking for one by going upstream through the other filament. "But then how could a bulb ground through a 'hot' lead?", I hear you ask. It will search backward through the hot lead until it finds a ground through another bulb in the same circuit. In effect, the grounded bulb and the ungrounded bulb end up wired in series.

Related diagnostic questions...

With headlights off, is the intensity and frequency of the right turnsignal equal to the left?

With the turnsignal off, are the highbeams of equal intensity?

When right turnsignal and highbeam are failing, is there any faint glow in either one at all?

When operating the right turnsignal with the highbeams on (thus causing the right highbeam to fail) will the right highbeam go on when you pull the dipswitch stalk toward the steering wheel? This headlight flashing switch draws on a different power source altogether.

What about the right rear turnsignal?

What happens if you disconnect the bullet connector to the right highbeam? Does the turnsignal still fail when the headlamps are turned on? Headlamps also being dual-filament bulbs, I'd check there for a faulty ground also.

I have more questions than answers but I would suspect faulty grounds wherever there are dual-filament bulbs: the right front turnsignal/parking lamp, the right headlight, and the right rear turnsignal/parking lamp.

Because of the involvement with that highbeam, I am inclined to discount the hazard switch. Usually, if the hazard switch fails, there won't be any turnsignal at all.

And if this was an outright short, you would have evacuated a lot of Lucas smoke from the system by now - since the headlight circuits are hot all the time, unfused.

Please do keep us informed. This is as fascinating as it is aggravating.

Allen
Allen

Allen,
I've just read your post and haven't had time to investigate all your questions, but I will. Thanks for some diagnostic leads as where to look. But...I'm focusing on your comment that "usually if the hazard switch fails, there won't be any turn signal at all." I am lead to believe there are two separate "flashers". One for the blinkers, one for the hazard switch. I've located the blinker flasher but cannot find the hazard flasher. These may be related or not. I'll print out your post and head to the garage.......thanks for the interest. As Daniel noted, there might be a flasher in the center console. I have no radio, but I'll be damned if I can find it!
Thanks guys, I'll check it all out tonight and let you know.
John
John

Allen, a few quick answers to your questions...
#1) With headlamps off, both blinkers flash at the same intensity and frequency.
#2) There is NO right highbeam...but the dash indicator shows the rt. blinker indicator on "steady".
#3) No faint glow in either the Rt. headlamp or turn signal.
#4) Highbeam "passing flash"...Rt. headlamp does not flash.
#5) With headlamps "on" neither front or back signals work.
#6) Disconnecting the bullet connector will have to wait until tomorrow. I will have to remove a horn to have a clear view. Blue with white tracer, I believe.

Thanks again,
John
John

Daniel,

I found the flasher, thank you. I had to remove the center console and found it screwed to the frame. It does not look anything like the one I have as a replacement. 2 terminals on the old, 3 terminals on the new.
John
John

As mentioned, I found the flasher. I also found a disconnected ground wire and a loose high beam wire on the right side. Problem solved.....not really. Now the LEFT side front won't flash with the head lamps on, as they do with the lamps off. Should there be a ground wire on the left side front too? I'm getting conflicting stories from parts people.

The hazard flashers work now, too!

Thanks,
John
John

This thread was discussed between 10/08/2005 and 13/08/2005

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