Both turn signals and brake lights are powered through the 2nd fuse up in
the 2- or 4-way fuse block, but if this had failed a number of other
circuits like all the electric instruments and reversing lights would also
be out. The brake lights and turn signals use separate green wires right
back to the fuse block, it could be bad connections here. A Lucas 35amp
fuse has a 17amp load rating and a 35amp blow rating.
According to my diagrams a North American 71 has hazards, and the most
common cause of turn signal failure in a car with hazards is the hazard
switch. The hazard switch disconnects the turn signals when the hazards are
on, and reconnects them when they are off, but only if the switch is working
properly. You can check this by bridging the two green wires on the back of
the hazard switch. If it is the switch it can sometimes be temporarily
fixed by flicking the switch on and off a few times, or more permanently by
dismantling and cleaning it. Failing that check for 12v on the green and
light-green/brown wires on the turn flasher to determine whether the problem
is in the feed, the flasher, or the wiring up towards the turn switch.
The brake light problem could be the switch, the green feed to the switch,
or the green/purple from the switch to the 4-way connector in the boot.
Look for 12v on the green side of the switch (ignition on) and the
green/purple side of the switch (ignition on and pedal down) to see which
way to go.
You might like to have a look at the web site below for individual
schematics - select 'Spanners', 'Electrics' and 'Schematics'.
PaulH
http://www.mgb-stuff.org.uk
----- Original Message -----
From: Rick Wagner <wagner@fuse.net>
To: <mgs@autox.team.net>
Sent: Thursday, August 03, 2000 10:35 PM
Subject: Electrical issue
> Ok.....I know the Lucas electrical systems cause many headaches, so prior
> to me cleaning every connector and tracing wires I figured I would ask a
> few questions. First I have a 71 MBG Roadster. Headlights/Taillights/side
> markers and reverse lamps all work fine. However, the Break lights and
> Turn signals do not work at all. I have checked the Fuse and that is fine.
> Does anyone have any idea what it could be? What are the first 3 or 4
> things I should check?
>
> Thanks
>
> -Rick
>
> --
>
>
> "We don't know who we are
> until we see what we can do"
>
>
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