At 10:11 PM 11/6/99 -0500, Keith Gernert wrote:
>I just recently acquired a 1979 MGB ....
>....
>The right turn signal does not work when the headlights are on.
Congratulations, and welcome to the mysterious world of Lucas electrics. I
shall attempt to demystify it a little.
Before 20 other people echo it to the whole mailing list, check the ground
connection(s), black wires, near the RF headlight and parking lights.
There will be a 4-way connector there with probably three black wires
plugged into it, one from the headlight, one from the parking light and
turn signal assembly, and one going to a ground screw on the body. On your
"new" car (newer than mine) there may also be another black wire there from
the side marker lamp (if it does not ground exclusively on the fender).
This ground connection is shared by all the lamps in the vacinity. If it
is not grounded on the body the parking light and turn signal circuits will
be finding a ground return through the headlight bulb filaments and from
there on to other grounding points in the wiring harness. In this case the
parking and signal lamps will still work, but the lamps will be a little
dimmer than normal, and the signal may blink at a little diferent speed,
because the other devices now in series with these lamps makes for a little
more resistance in the circuit and a little less current. Then when you
turn on the headlights the downhill side of the marker and turn signal
circuits suddenly see a higher voltage on the wire that they were
previously using for their ground return. This may dim those lights a
little more, and the turn signal is likely to stop blinking all together
with the reduced current, although the bulb may stay lit.
>.... when the headlights are on, the right rear turn signal lamp stays on,
and the right turn indicator on the dash stays dimly lit. This is without
the turn signal stalk being engaged. Flipping it makes no change. Weird.
This would be caused by the headlight finding a ground return through the
right rear TL and TS bulbs, and in the process presenting a small voltage
to the dash indicator bulb which is hooked to the turn signal circuit.
>Now, the right side high-beam does not work, either, but I hope that has
nothing to do with this.
That might be just a burned out bulb. Otherwise it may be a bad connection
going to that lamp. With the lights on high beam, check for voltage on the
blue wire with white stripe near the RF headlight, which should also be
plugged into a 3-way connector running power from the dipper switch to both
headlamps. If you get voltage there, remove the headlamp bulb and check
the connector there for corrosion. Otherwise test the bulb or try a new one.
Regards,
Barney Gaylord
1958 MGA with an attitude
http://www.ntsource.com/~barneymg
|