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Automotive headlamp/LED circuit help

Discussion in 'LEDs and Optoelectronics' started by cdnram, May 25, 2013.

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  1. cdnram


    May 25, 2013
    Hi y'all,

    I am trying to build a jumper harness to allow the use of a new style headlight assembly into an older generation of the same vehicle. I have been able to make everything work except the daytime running lights which are now an LED bank as opposed to the low-voltage powered high beam circuit. All circuits are controlled through the vehicle's TIPM (total integrated power module) so I'm not able to go in and change any of the logic, which means I'm forced to use the input voltages that I'm given.

    The issues I'm coming across with this circuit is I have to activate the LEDs off of the existing DRL circuit which is also the high-beam circuit:

    1) The DRL circuit is automatically triggered when the vehicle is put into a gear and the lamp receives 3.3V and I have tried to power the LEDs directly from this line and while they will illuminate they are dim and there is a very noticable humming from the headlight assembly.

    2) When the high-beam circuit is activated the input voltage changes to 12V.

    3) The DRL circuit needs to be deactivated when the turn signal is activated; this occurs in the TIPM and works fine when hooked directly into the existing DRL circuit, but when the high beam circuit is active it doesn't deactivate the circuit, so I can not use a general 12V ignition controlled circuit.

    Now, I have tried running a relay with the 12V coil powered by the DRL circuit but the input voltage of 3.3V is not enough to activate the 12V relay and I can't find a 3V coil relay that would be able to handle the 12V 55W input of the high-beam circuit.

    My ideal system would be one that is able to be activated with the 3.3V DRL circuit but when the 12V input is applied it will block input to the coil relay. This would allow the DRL circuit to function normally but not be affected by the higher input voltage of the high-beam circuit.
  2. discomark10


    Sep 18, 2013
    You could use a relay to turn of the led's when turn signal is activated and a fet instead of a relay as they require allot less to turn on.
  3. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
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