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Old 08-16-2017, 03:03 PM   #1 (permalink)
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Default LED turn signals turn off when headlights on

Put this in General, as opposed to Samurai specific, as I wasn't sure if this was an issue with the Samurai itself, or something to do with adding LEDs to any vehicle.

Adding LED turn signals in to a '87 Samurai. Already switched out the factory relay for an LED compatible electronic unit, so I don't have the rapid flashing issue. These are also complete replacement units, not just adding LED bulbs to the factory housings.

At first I tried to just connect straight to factory plugs, and they didn't work at all. Eventually figured out that if I provide power via the factory turn signal connector, and ground direct to the battery, the turn signal operates correctly.

BUT, if I switch the headlights on, turn signal goes off completely. The rear factory turn signals continue to operate correctly, headlights on or off. I thought it might have something to do with Suzuki's switched ground set up, but after looking at the wiring diagrams, it appears that the turn signals are switching the power.

I'm stumped here. Would this be indicative of a bad ground? I did notice that the turn signal LEDs were considerably dimmer once I grounded to the body instead of direct to battery, so I was planning on adding additional ground jumpers to the body and frame, but even with an additional jumper to battery, the situation didn't improve.
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Old 11-07-2017, 05:28 PM   #2 (permalink)
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Gvs 2 has a reply over in 2g forum about hi/lo headlights, might be of some help if you didn't figure it out yet. These critters are not wired like Detroit iron.
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Old 11-07-2017, 06:16 PM   #3 (permalink)
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Sounds like your doing all the right things.

Link to other thread?


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Old 11-07-2017, 06:25 PM   #4 (permalink)
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First - if you "ground" direct to the battery - how can you have a bad ground?
Second - the headlight circuits are (or should be) completely separate to the turn signals and therefore it should not be possible for there to be any interaction between the two.
Third - if the LED is "grounded" direct to the battery, the only way to get the LED to turn off completely is to remove the power supplied to it.

A couple of questions for you ...
- which battery terminal did you "ground" the LED turn signals to - positive or negative?
- do the LED signals go off when the park lamps or is it only when the head lamps are on?

The fact that the rear signals continue to work tells me that you still have power to the turn signals which leads me to wonder if you have the LED turn signals wired incorrectly (they are sensitive to polarity) and if they go off when you turn the park lamps on, that would further suggest that you have the polarity reversed and have "grounded" them to the battery positive.

Get a test meter and start making voltage measurements -
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