Oliver:
Let's go after the problems one at a time.
Fuel Gauge:
If your temp gauge appears to be reading accurately, then you don't have
a voltage stabilizer problem.
Go under the rear of the car, pull the green striped wire off the fuel
sender and ground it to the chassis. With the ignition on, the fuel
gauge should sweep all the way to full.
If it does that correctly. Clean and re-connect the wire to the sender.
If the gauge still reads empty, the float on the sender may have failed,
or the sender itself may have an internal bad connection. In which case
you will need to pull the sender and check it out/replace.
Tail Lights and Dash Lights:
These receive power from the headlight switch. If your headlights are
working, then the switch is getting power.
The side lamps and dash lights only have this one common point, so it is
a given that either the red wire connector at the switch is not making
good contact, or there is an internal problem with the switch.
These 1973-76 headlight switches were pretty short lived, so it's
probably the switch.
Your historical fix is the best call. The most likely culprit is a bad
contact inside the headlight switch. Futzing with it in the past would
get it working, but after enough times carbon build up would get so bad
that futzing doesn't work any more. Removing the switch, dismantling it
and cleaning the contacts or replacing the switch will get you going
again.
This is where a volt meter or test light is really handy. The feed to
the sidelamps from the headlamp switch is the red wire. Check to see if
you have power here with the switch on. I'm betting you don't.
As you surmise, the brake lights are a totally different circuit. If one
works and not the other, the switching is all ok you either have a bad
bulb, bad socket contact or more likely the connector from harness to
lamp assembly has become unplugged.
Boy, three unrelated electrical problems in one car.
All of these problems are pretty typical as the car gets older. Fix them
correctly once and you won't have the same problem again.
BTW. The recommendation to replace the 4 position fuse box is a good
one. Once you start having electrical problems caused by age, the fuse
box is going to start becoming a problem as it is prone to corrosion
between the rivets and clips. Typical symptoms will be a loss of
ignition switched circuits, such as the turn signals, brake lights etc.
I highly recommend replacing the fuse box and the headlight switch on
any older crash dash MGB. Also take the steering column cowl off and
clean all the terminals of the turn signal/High-low beam switch. This
prevents most of the electrical gremlins from getting out of hand.
Kelvin
> -----Original Message-----
> From: mgs-bounces@autox.team.net [mailto:mgs-bounces@autox.team.net]
On
> Behalf Of oliver
> Sent: Tuesday, July 10, 2007 8:35 PM
> To: mgs@autox.team.net
> Subject: [Mgs] i think i know what to do
>
> 1973 mgb roadster, pretty stock less the pollution equipment plus non
> functional add on a/c
>
> the gas gage has read low for some time.
>
> tonight i filled up and it still read dead zero as opposed to just
being
> pessimistic
>
> on the way back i realized i had no tail lights or dash lights. ok.
> btdt.
> pull the light switch, futz with it, put it back in, usually fixes it.
> not
> tonight. brake light works one side only, but that's been that way
for a
> while. i think thats unrelated.
>
> switching in and out of overdrive at one point, which i think was a
> coincidence, the missing lights shine on and work all the way home.
>
> conclusion: errant ground under the dashboard, possible bad voltage
> stabilizer???
>
> thanks for your help.
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