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Re: TR6 flasher/directionals

To: jesup@cbmvax.cbm.commodore.com (Randell Jesup)
Subject: Re: TR6 flasher/directionals
From: pwv@tc.fluke.com (Pat Vilbrandt)
Date: Wed, 6 Oct 1993 08:52:45 -0700
On Oct 4,  7:57pm, Randell Jesup wrote:
>       I just replaced the flasher unit in my '70 TR6.  After installing
> it, I still had no blinks until I fiddled with the rear bulb carriers to
> give them a better ground (stupid design).  That made the right side work,
> in fact it flashes annoyingly fast.  The left side, though, is about .5
> hertz, or maybe .25Hz, and then only if the engine is running.

It sounds to me like you have (cue ominous background music, crank on reverb)

     ... THE DREADED BAD GROUND SYNDROME!!!!

>       I woulnd't be confused except that the resistance for the left and
> right circuits, measured from the flasher, is almost identical (~20 ohms
> left, ~18-19 right).

Both of those numbers are too high.  Should be about half that amount.  And
the voltage at the bulbs when on should be almost the battery voltage.

>       To add to the amusement, when driving home at night saturday, I
> noticed the lights were dim.  Neither flasher would work, and trying to use
> them caused the headlights to dim more.  High beams came on slowly and even
> dimmer than lows, it seemed.

Yep, bad system ground.  I'm assuming that you've already checked the
grounding straps and the battery ground connection to the engine/body.
Good.  It's quite possible that there's enough rust in the body (in a 24 year
old LBC?? - nah!! ;^) that there is no longer a low impedance connection thru
the body.  Try this: connect one end of a long wire to the ground terminal on
the battery.  Stretch the other end around to the left side back of the car
and measure the voltage from both sides of the bulb to this wire.  Bet you'll
find the 2 volts you're missing!

I've seen people "cure" problems like this by running a piece of #10 wire from
the back bumper to the engine block.  All of you with slow, erratic turn
signals might want to consider this!

   Pat Vilbrandt      Fluke Corporation      Everett, Washington USA
   pwv@tc.fluke.COM or: { uunet, uw-beaver, sun, microsoft }!fluke!pwv



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