[Mgs] 1972 MG Midget wiring question

[Paul Hunt]

If neither side works at all not even glowing with the turn signals, but the 
hazard signals flash all four corners, it is probably the hazard switch, 
power for the turn signals comes through this when the hazards are off.  Can 
also be broken connections in the green 12v fused ignition supply to the 
hazard switch, or the green from the hazard switch to the turn flasher unit, 
or the light-green/brown (colours are for an MGB) from there to the turn 
switch.  Also the turn flasher unit or turn switch themselves.  An easy 
circuit to diagnose, with the ignition on (you might want to disconnect the 
coil to stop it overheating) track 12v with a test-lamp or meter through the 
hazard switch and turn flasher unit to the turn switch.  On an MGB the 
washers and turn flashers and other circuits are all on the green circuit so 
if two fail together that indicates the problem could be from where they 
join back towards the battery.  But it could also mean you have two 
independent faults!

If the both lamps each side glow but don't flash either the turn flasher is 
faulty or there is insufficient current flowing to trigger the turn flasher. 
Unless the bad connection is very bad you are unlikely to spot different 
levels of brightness as only a slight dimming is enough to cause the 
problem.  This is much more difficult to track down as only slightly bad 
connections can cause it, and you may have several very slightly bad 
connections in the circuit.  If both sides do it it could be in the green 
and light-green/brown circuits as above, in fact anywhere back through the 
green, fusebox, white, ignition switch and brown circuits.

If one side works OK but the other side just glows it is a bad connection or 
incorrect or tired bulb that side.  Connections can be anywhere from the 
turn switch, bullet connectors out to the lamp units, bulb to bulb holder, 
and light unit to body (or wired ground where provided).

Of course if one corner doesn't glow at all, that is the designed warning 
for bulb failure, which can be a broken connection out through that corner. 
New flasher units can sometimes get non flashers going as they seem to be 
slightly more sensitive, but as they 'burn in' they will fail also, 
indicating the problem is elsewhere.

PaulH.

----- Original Message ----- 
From: <Rabeys at aol.com>
To: <mgs at autox.team.net>
Sent: Saturday, June 09, 2007 1:51 AM
Subject: [Mgs] 1972 MG Midget wiring question


> Can't seem to get my signals to work.  The hazard switch works and all 
> the
> lights blink, but when I try left and right, nothing.  I checked every 
> ground
> I can think of and cleaned the connections.  I just changed the  relay and 
> it
> worked for a short time, but only  the right signal.  The  right would 
> blink,
> but it seemed slow.  The left didn't blink at all  initially, but the 
> lights
> came on and stayed on.  Every so often it would  blink, about once every 
> 10
> seconds or something weird like that.  Now  neither works.  I'm at a loss. 
> I'm
> not sure if its related, but the  washer switch isnt working either.  The
> signal switch is pretty new and all  connections look great.  I even tried 
> a
> different switch from my parts  car.  Everything worked except the turn 
> signals
> again.  Seems to  coincidental.  I'm sure its something simple.  Any 
> ideas?
>
>
>
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