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Led Turn Signal Bulbs/lamps


wwest
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The electronic turn signal flasher in my '95 LS400 is mounted in the driver's side left "kick-panel" at the very top and forward toward the firewall.

The circuit is designed to flash at a normal rate if at least two bulbs are working, 3.6 amps of total current draw. It also flashes at the normal rate when the hazard switch is on, 7.2 amps of current flow. But in turn signal mode if one bulb should fail the relay will fast-flash to make the driver aware of the failure.

It does this by sensing the current flow through a resistive nichrome wire "link" which is carefully trimmed to drop 80 millivolts, 0.080 volts with both turn signal bulbs working.

So the goal, to prevent fast flashing with the low current draw of LED lamps, is to replace that nichrome wire link with a resistor that will drop at least 80 millivolts with both LED turn signal lamps powered.

In my case each amber turn signal LED draws 0.120 amps, 0.240 total, so I wanted to replace the nichrome wire with a resistor of ~0.70 ohms.

I didn't happen to have a .7 ohm resistor on hand so I substituted a 1.0 ohm resistor.

With the 1 ohm resistor I don't get fast flash if one LED is out but...

In the picture the larger 1/2 watt blue banded 1 ohm resistor at the top replaced the nichrome link.

If you wish to have the viability of installing incandescent lamps temporarily should a LED lamp fail then I would recommend a 5 amp diode mounted in parallel with the 1/2 watt resistor, anode nearest in the picture, 12 volt B+ point. Otherwise the 1/2 watt resistor would not long survive a 1.8 amp current flow.

post-4016-1202595097_thumb.jpg

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wow that is totally different from my flasher on my 98 which has 8 wires integrating the hazard into it but in the same physical area.

Like i mentioned in your other thread i am getting a replacement unit which should plug right in with no worries of fast flashing.

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