Subject: Re: [Mgs] Update to lighting issue and another question

From: Barney Gaylord <[email-masked]>
Date: Thu, 04 Apr 2013 16:17:34 -0500

William,

Front sidelamps should have three wires, including a black grouinding 
wire.  This black wire plugs into a twin tube snap connector to 
ground headlampadn sidelamp to one black wire in the harness.  Final 
grounding point for that black harness wire (originally) is a hex nut 
on the tip of a longer fender bolt, second bolt above the air pan on 
right side, close to where youi find a bundle of snap connestors for 
the RH lamps

Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com

At 02:40 PM 4/4/2013 -0400, William Killeffer wrote:
>....
>The problem is that the left side front sidemarker light still does 
>not light up. It could be a bad bulb, but I want to clean its ground 
>connection. Trouble is, I am not sure where that is. A previous 
>email mentioned a grounding point near the starter relay, but I am 
>not sure where that is located. ....
>.....
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From: "PaulHunt73" <[email-masked]>
Date: Fri, 5 Apr 2013 08:47:42 +0100

An MGB, I seem to remember.  Side-marker lamps only have two wires - 12v 
supply and earth.  Originally they came on with the headlamps and there is 
an additional blue wire in the harness by the front headlights, but during 
1972 this changed to come on with the parking lights from a red wire in the 
harness by the headlights.  The earth is wired to black wires by the 
headlights, which goes back to a body earth by the starter relay.  However 
that earth also supplies the headlights, so if they are working it's not the 
body earth that is the problem.  Nor any of the connections by the 
right-hand headlight, but it could be the one bullet on the black wire from 
the side-marker by the left-hand headlight.  Locate the red and black wires 
from that side-marker, and test for voltage with a meter inside the 
bullets - don't dismantle them.  If you have no voltage on the red the 
problem could be either side of the red bullet by the left-hand headlight, 
or one bullet by the right-hand headlight.  If you have voltage on the black 
then the earth at that bullet is the problem.  If you have 12v on the red 
and nothing on the black then the problem lies between those two points i.e. 
either inside the light or the wires leading to it.

The only light unit on an MGB that has three wires including a black earth 
wire is the headlight unit.  All MGB rear light clusters have three wires 
but none are black, the light unit earths through its physical mounting. 
Chrome bumper front parking lights only have two wires and also earth 
through their physical mountings.  Rubber bumper front indicators do have a 
black earth wire but only two wires as they only have one single-filament 
bulb.

PaulH.

----- Original Message ----- 
> The problem is that the left side front sidemarker light still does not 
> light
> up. It could be a bad bulb, but I want to clean its ground connection. 

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