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MG MGB Technical - Flasher Location?

Can someone tell me where the flasher is for the turn signals? 1973 MGB partially assembled. Thanks, Tom
Tom

It's behind the glove box.

Clifton
Clifton Gordon

Pushed into a spring-clip, with two terminals having green and light-green/brown wires attached.

Not to be confused with the voltage stabiliser, sometimes in a similar location but screwed to the firewall, also with two terminals but green and light-green/green wires. Or the hazard flasher unit, which can sometimes be adjacent to the turn flasher, also in a spring-clip and with two terminals, but with brown and light-green/brown wires. Despite being the same colour the two light-green/brown wires on the turn and hazard flashers are *not* electrically the same and should not be reversed.
Paul Hunt

Thanks for the information, I found it and it must have a stuck contact? I replaced it with a modern flasher from Auto Zone and everything works fine. The replacement will flash without a "load" but the oroginals don't. Thats how you tell if/when you lose a lamp with the original flasher. BTW, it cost more than Moss but no shipping.. Rgards, Tom
Tom

"The replacement will flash without a "load" but the oroginals don't"

The replacement is a safety hazard, then, for the reason you state i.e. it *won't* flash differently if one (or both) bulb has failed. Personally I would never use one of these, the risk of getting rear-ended is just too high.

Modern turn/indicator flasher units should flash at double-speed if a bulb has failed, whereas the original units stop flashing and the remaining bulb (and tell-tales) glow permanently. Both warn you of bulb failure and allow you to take appropriate action i.e. hand signals or to take particular care when turning until you can replace the bulb.

So-called 'heavy duty' flashers are the ones that tend not to respond to bulb failure. The other thing to be aware of is that you haven't been sold a hazard flasher instead of a turn flasher. Turn flashers light the bulbs immediately the switch is operated, then start to flash off-on-off-on. Hazard flashers do nothing for a second or so when the switch is operated, then start flashing on-off-on-off. This delay in operation is another safety hazard should they be used in place of a turn flasher.

Some people who have slow or non-flashing when both bulbs are working chose to fit a modern flasher unit instead of fixing the root cause, which will be incorrect bulbs and/or bad connections.
Paul Hunt

Then in my situation where my left dash light turn indicator wont flash (but lights) and my right turn indicator will flash I must have a bulb or connection problem on the left side of car....is that correct? Thanks, guys.

JOHN
JW Colson

Correct. These can be tricky to track down, and there could be several small problems contributing, so you might not find a single point that is clearly wrong and fixes it. the best way to tackle these is to bypass the turn flasher unit by connecting the two spades together and turning the ignition on. Plot the voltages through the right-hand i.e. working side i.e. green/white wires first at all the connections, which are typically at the switch, where the switch harness joins the main harness, where the main harness splits out to connect to the rear harness and goes back in for the front lights (in the mass by the fusebox), at the bullet connectors by the headlight, on the bulb holder live side, and bulb holder ground side. On each bullet connection test both sides, making sure you touch the bullet itself with the voltmeter provbe and not the sleeve of the connector.

With the exception of the last one ideally you should see battery voltage all the way through, but some volt-drop as you progress is inevitable. On the bulb holder ground you should see zero volts, if you see any voltage there is a bad connection to ground, which is via the fixing screws on all but rubber bumper fronts, which have a ground wire going back to connectors by the headlight.

Then do the other i.e. faulty side, and compare voltages. Any sudden drop in voltage from one point to another indicates (ho ho) a bad connection between those two points.

Bear in mind you could have tired or incorrect bulbs, swapping sides will prove/eliminate that. I've also known of two cases where there was a bad connection between the brass bulb holder and the alloy casting in rear lights, so check each side of every metal to metal conenction inside the light units as well as the wiring connections.
Paul Hunt

This thread was discussed between 31/05/2008 and 04/06/2008

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