Subject: RE: Strange Blinker Bulb Problem
Author: murp-@aol.com
Date: May 10, 2001, 11:27 PM
Post ID: 1706678650
Keith,
The flasher unit is connected in series between +12V (when the turn
signal is on) and its load, which is the bulb. When the load resistance
is low, it will blink fast, and when the resistance is high, it will
blink slow. It looks to me that you have a bad bulb, in which there is a
low resistance to ground for one filament. This is why, when you reverse
the bulb connections, the flasher (rather than the blinker) blinks fast,
or vice versa. That is why I'm really surprised that a new bulb didn't
cure the problem. There is a slim possibility that your bulb socket has
an intermittent fault to ground, and that inserting the bulb causes
this, but this is unlikely because the fault to ground switches from
flasher to blinker (and vice versa) when the bulb is reversed. To
troubleshoot some more, I need a little more information, like whether
the blinkers and flashers use 2 different flasher units, or are switched
between the same one. In any case, I would remove the flasher unit and
measure the resistance to ground of the lead which goes to the bulb
socket. Make sure this is open circuit with the bulb removed, and check
it when the bulb is inserted. I'm not sure what the resistance through
the filament should be, but you can check that it is similar to the
resistance on the other side. Let me know how it turns out.
Brian
'74 Eldo
'78 T3
Keith Ruff wrote:
So confused and frustrated on this one. I got the blinker working fine, so I'm not worried. Flashers work but blink quick and in short burst. But, this dilemma really has got me wanting an answer. Checked all the connections again and even used a lead off of my meter and touched it to the bulb base, then to ground. No change. Checked the blinker switch and flashers, they seemed fine too. It is too strange that one filament on a dual filament bulb can cause either the blinker or flashers to not operate properly (depends on how the bulb is installed). Moe at Cycle Garden says that the flashers operate off of resistance, so perhaps it's time for a new flasher - they depened on the wattage of the bulb to operate. Others mention ground problems or a short in one of the 2 wires. Thing of it is, if I switch the bulb around, or just switch the wires going to it, it will cure the faulty light (blinker or flasher) but then start a problem for the other light. This would tell me that there isn't a ground problem or break in a wire because it would be bad all of the time, not just when the bulb filament is changed. Changing bulbs didn't help either. For some reason, one side of bulb is causing this problem and I can't figure it out. Guess these problems occur with 30 year old wiring harnesses? Not sure what to do now, like I said, it's not a true concern since I will rarely use the flashers, just one of those things I want to figure out since it has eaten me mentally. My auto mechanic feels one of the wires is bad and has offered his assistance in helping me troubleshoot, will take him up on his offer when I get a chance. Keith Ruff 71 Police Amabassador - NJ Ian Adkins wrote:
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