Hi Chris
Seems this comes up every year or so.. A response I wrote up
a while ago follows.
BTW the running light can work even though the ground is missing,
as its current finds a sneak path to ground through all the larger
turn signal bulbs.. If it is the ground, when the turnsignal tries
to turn on.. the running light in that fixture should go off.
For a simple explanation... Voltage is just like pressure and
Current is just like water volume in a plumbing system. The
Voltage "pushes" the current through all the wires and loads
(light bulbs). For a much better explanation with some very
simple math that relates the voltage to the current given the
load's resistance see any High School physics book.
Steve F
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Steve Finberg W1GSL w1gsl@mit.edu
PO Box 397082 MIT Br Cambridge MA 02139-7082 617 258 3754
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ADD A REAL GROUND WiRE. (c) 1996 Steve Finberg
Failure of the front turn signals is common on the series IV and V
Alpines and late Tigers. The usual cause is a poor ground return
connection at the front lamp.
This is due to Lucas's failure to provide a proper ground
connection. The circuit depends on the mounting screws making a
good electrical connection from the chrome body of the lamp to
the "Timmerman" nut and them to the steel fender. Any corrosion
in the path will keep the lamp off. To top it off this is all
done with a mounting screw that is tightened against the plastic
lens and only peripherally contacts the chrome lamp body as it
passes through a clearance hole. Its a wonder it ever works.
Often all that is required is to loosen and retighten the
mounting screws, or possibly disassemble the mount and clean all
the surfaces. There should be much less than one ohm resistance
from the chrome lamp body to the battery negative terminal. Be
careful not to over tighten the mounting screws lest the plastic
lens crack...
A much more robust solution is to add a ground wire from the
chrome lamp body to the car ground. Tap a hole in the lamp body
for a #6 screw. Run a #20 or larger black wire to point where
the headlight is grounded. It is near the bonnet hinge.
Thoughtfully Roots left a spare hole.. Use a solder lug at the
lamp body and a "bullet" connector at the ground end. There is
plenty of room for the screw head in the rubber mounting spacer.
Occasionally the slide in contacts for the running light bulb
severly corrode. This occurs when moisture has gotten into the
lamp assembly due to a cracked lens. The lamp fixture can be
salvaged using one of the replacement pop-in the hole lamp holders
available at most parts stores. Drill out the old contacts
(1/2" hole I think), and just pop it in. Be sure to moisture
seal the assembly. The replacement bulb holder should have its
own ground return wire which will ground the chrome turn signal
body.
It has been a long time since I did this mod so forgive me the
details.. But for the last 14 years my turn signals have been
reliable and I have had no trouble with cracking lenses.
RE the flasher not blinking...its not a bug.. its a feature.
It tells you its time to clean the connections... or
that a bulb is blown...
Steve F
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