[Mgs] Question on MGB Light Switches

John Di Fede difejo at optonline.net
Tue Nov 15 16:05:17 MST 2016


Jack, Sarah,

It has been a while since I've studied my 1973 MGB wiring diagram.

I think there are two separate circuits for the high beams.  The regular
headlight high beam circuit and the flash to pass circuit.

I would check your light switch on the dash.  Check it to verify that it is
making the proper contacts within the switch to send power to the high beam
circuit.  I believe the dash switch sends the high beam power to the stalk
on the steering column when you have the headlights switched on.   Pushing
the stalk forward then further completes the circuit and turns the high
beams on.    These dash switches are known to burn out from handling the
full current needed to operate the headlights.   

This stalk also has a flash to pass circuit that is activated when you pull
the stalk backwards.   I think there is a constant power supply to the stalk
that supplies the power to this circuit when you flash to pass.   This power
supply is a distinct circuit that does not flow through the headlight
switch.      This is why the flash to pass circuit works in the daylight
when your headlights are not switched on.    

The problem I think you have is that the dash switch is not supplying power
to the stalk for your high beam circuit.  

Also, there is known problem with the 4 way flasher switch in some (my 1973)
MGB where if you move the switch on and off vigorously the flashers will
work properly.  Perhaps this will fix your headlight switch.  Move the
headlight switch on off a few times vigorously and see if that helps.  If
not remove the switch and test it with a volt ohm meter.

I believe the dash switches are available through Moss and the major parts
suppliers.

Check you wiring diagram.  Good luck

John Difede
1973 MGB
     

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Subject: Mgs Digest, Vol 114, Issue 6

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Today's Topics:

   1. Question on MGB Light Switches (Jack Wheeler)
   2. Re: Question on MGB Light Switches (S. Carr)
   3. Re: Question on MGB Light Switches (David Councill)
   4. Re: Question on MGB Light Switches (S. Carr)


----------------------------------------------------------------------

Message: 1
Date: Mon, 14 Nov 2016 23:52:14 +0000 (UTC)
From: Jack Wheeler <jwheeler1947 at yahoo.com>
To: "mgs at autox.team.net" <mgs at autox.team.net>
Subject: [Mgs] Question on MGB Light Switches
Message-ID: <562886890.4993881.1479167534369 at mail.yahoo.com>
Content-Type: text/plain; charset="utf-8"

I have a 1971 MGB that has a problem with the headlight switches.? Before I
start replacing everything and hope for the best, I thought I would ask if
any of you has had a similar problem, or can suggest a possible solution.
When I push bottom of the light switch (on the dash) to the first position,
the parking lamps and tail lights come on.? OK, so far.? When I push the
light switch to the second position, the headlights come on with the low
beam.? OK, again.? Now comes the problem.
When I move the stalk on the left side of the steering column forward
(toward the dash), the lights go off (i.e. no high beams).? If I pull this
stalk all the way towards me, the high beams do come on, so the bubs are
apparently OK.
My first thought was that it may be the high beam/low beam and direction
indicator switch located on the steering column.? Does this sound right??
Any other thoughts?
And finally, if this is the case, is this switch available, and if so, do
you have a source you would recommend.
Thanks for your help.
Jack Wheeler



   







   
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Message: 2
Date: Mon, 14 Nov 2016 22:47:17 -0500
From: "S. Carr" <britfan1 at epix.net>
To: <mgs at autox.team.net>
Subject: Re: [Mgs] Question on MGB Light Switches
Message-ID: <8613609E54FF4FA4B461C2355C4ECDD3 at HomePC>
Content-Type: text/plain; charset="utf-8"

I hope somebody comes up with the answer to this, as I have exactly the same
problem on our ?71 B/GT.

After removing the steering column cowl (and putting it back together
without breaking the plastic where the screws go is even harder than
removal?good thing we had another one in the spares bin!) I noticed that the
contact that apparently completes the forward-for-high-beam circuit was no
longer there?apparently burned away.  So I raided our spares bin for a used
stalk?from another year, as it has icons on it that the one in the car
doesn?t, but the plug and all the wire colors matched and the ?missing?
contact was there?and plugged it in while things were still apart.  Still no
high beams (though, like Jack, I can flash them by pulling the stalk
backward), so I put everything back together with the original stalk, and
try not to drive the car at night....

Help us both!

Sarah Carr
?71 B/GT in PA


From: Jack Wheeler via Mgs
Sent: Monday, November 14, 2016 6:52 PM
To: mgs at autox.team.net
Subject: [Mgs] Question on MGB Light Switches

I have a 1971 MGB that has a problem with the headlight switches.  Before I
start replacing everything and hope for the best, I thought I would ask if
any of you has had a similar problem, or can suggest a possible solution.


When I push bottom of the light switch (on the dash) to the first position,
the parking lamps and tail lights come on.  OK, so far.  When I push the
light switch to the second position, the headlights come on with the low
beam.  OK, again.  Now comes the problem.


When I move the stalk on the left side of the steering column forward
(toward the dash), the lights go off (i.e. no high beams).  If I pull this
stalk all the way towards me, the high beams do come on, so the bubs are
apparently OK.


My first thought was that it may be the high beam/low beam and direction
indicator switch located on the steering column.  Does this sound right?
Any other thoughts?


And finally, if this is the case, is this switch available, and if so, do
you have a source you would recommend.


Thanks for your help.


Jack Wheeler
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Message: 3
Date: Tue, 15 Nov 2016 07:56:28 -0800
From: "David Councill" <dcouncill at karamursel.org>
To: <mgs at autox.team.net>
Subject: Re: [Mgs] Question on MGB Light Switches
Message-ID: <009401d23f58$d41d07f0$7c5717d0$@karamursel.org>
Content-Type: text/plain; charset="utf-8"

These turn signal switch units should be readily available new from Moss
Motors and other distributers. I replaced mine at one point several years
ago in my 71 BGT (most parts now in my 72B).

 

http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29081  - part
number 27

 

Also, to be sure, test the switch while the cowl is still off to insure the
high beam part is working and not partially obstructed by the cowl.

 

David Councill

72 B

67 BGT

64 B

 

From: Mgs [mailto:mgs-bounces at autox.team.net] On Behalf Of S. Carr via Mgs
Sent: Monday, November 14, 2016 7:47 PM
To: mgs at autox.team.net
Subject: Re: [Mgs] Question on MGB Light Switches

 

I hope somebody comes up with the answer to this, as I have exactly the same
problem on our ?71 B/GT.

 

After removing the steering column cowl (and putting it back together
without breaking the plastic where the screws go is even harder than
removal?good thing we had another one in the spares bin!) I noticed that the
contact that apparently completes the forward-for-high-beam circuit was no
longer there?apparently burned away.  So I raided our spares bin for a used
stalk?from another year, as it has icons on it that the one in the car
doesn?t, but the plug and all the wire colors matched and the ?missing?
contact was there?and plugged it in while things were still apart.  Still no
high beams (though, like Jack, I can flash them by pulling the stalk
backward), so I put everything back together with the original stalk, and
try not to drive the car at night....

 

Help us both!

 

Sarah Carr

?71 B/GT in PA

 

 

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Message: 4
Date: Tue, 15 Nov 2016 13:38:27 -0500
From: "S. Carr" <britfan1 at epix.net>
To: <mgs at autox.team.net>
Subject: Re: [Mgs] Question on MGB Light Switches
Message-ID: <FF5342EF69DF4012A5633ABB4B01FEE1 at HomePC>
Content-Type: text/plain; charset="utf-8"

Thanks David ? I  know a replacement is available, but I?m baffled as to why
the second, apparently good, unit didn?t work either....

Sarah

From: David Councill via Mgs
Sent: Tuesday, November 15, 2016 10:56 AM
To: mgs at autox.team.net
Subject: Re: [Mgs] Question on MGB Light Switches

These turn signal switch units should be readily available new from Moss
Motors and other distributers. I replaced mine at one point several years
ago in my 71 BGT (most parts now in my 72B).

 

http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29081  - part
number 27

 

Also, to be sure, test the switch while the cowl is still off to insure the
high beam part is working and not partially obstructed by the cowl.

 

David Councill

72 B

67 BGT

64 B
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