355 interior LED intensity problems / what's on the dimmer? | FerrariChat

355 interior LED intensity problems / what's on the dimmer?

Discussion in '348/355' started by hjp, Aug 5, 2015.

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  1. hjp

    hjp Formula Junior

    Feb 23, 2013
    591
    Kansas City, Mo.
    Full Name:
    Jerry Peterson
    There are 3 lights that light up all the elements in the HVAC panel except the
    STOP" and "REC" buttons. These 3 lights are tied together and are on the dash dimmer control and are only on when the car lights are on. If the car lights are off, they are off. My question is about the other 2 lights that are inside the "STOP" and "REC" buttons. My car is all apart right now so I can't check for myself. Hopefully one of you can help me.

    I believe these 2 lights are both off in the up position and come on only when the buttons are pushed. Is this correct? Do the car's lights have to be on for them to work or do they work regardless of whether the car lights are on or not? In other words, as long as the key is on they work and are independent of the car's lights. Is this correct?

    Here's what this is all about. Much of the interior lights in my '96 355 Spider have been replaced with LEDs. But there's a problem with the intensities. When the dash lights are full up on the dimmer, they are too bright. That's easily fixed by turning them down. But when I do, the HVAC lights are way too dim since they are on the same dimmer. I have the Hill Engineering HVAC overlay. The 3 general lights in my HVAC panel have been replaced with single element LEDs but all my dash lights have been replaced with 3 element LEDs. That's because the 2 types of LEDs fit the OEM sockets that way. The lights inside the "STOP" and "REC" buttons are very tiny incandescent bulbs and can't be changed to LEDs due to their size and shape.

    Here's my plan to fix this. None of the other center console lights are on the dimmer. Just the HVAC panel lights. When the dimmer is full up, the HVAC panel lights then match the other console lights in intensity perfectly. Since I see no reason why they need to be dimmer controlled any more than the other console lights, I plan to take them off the dimmer and put them on a constant 12 volt circuit that is switched with the car's lights just like the rest of the console lights. This would also be reversible if ever needed.

    So back to my questions. I'm trying to figure out what circuit might work for my purpose. It needs to be a constant un-dimmed 12 volt circuit and be switched with the car's lights. If the "STOP" and "REC" button circuit feed is not on the dimmer and is also switched with the car's lights, then this should work and would be convenient since its on the same circuit board. If not, another possible candidate might be the ash tray light but it would have to be tied in. Not a problem, just not as convenient.

    So, can one of you guys help me with this?
     
  2. m.stojanovic

    m.stojanovic F1 Rookie
    Silver Subscribed

    Dec 22, 2011
    3,288
    Serbia - Niš
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    Miroljub Stojanovic
    I have a 348 but I think the principles are similar.

    The lights inside the switches should be activated by the ignition switch, not dimmed.

    The HVAC and instrument illumination comes on with the car lights, both on the same dimmer. The dimmer has incoming 12V and regulated outgoing to the HVAC and instrument lights. To balance the intensity, you can either insert a resistor in the line dimmer to the instruments or provide full 12V to the HVAC. You have to determine the value and the size (wattage) of the resistor by trial. I suggest you buy a number of resistors in the range 82 to 270 Ohm (2 Watt to be on the safe side). Once you determine the correct Ohms check how hot the resistor gets after few minutes. If too hot, go for higher wattage. If you prefer full 12V tot he HVAC, just disconnect the HVAC illumination line from where it is connected to the dimmer and connect it to the incoming 12V supply to the dimmer.
     
  3. hjp

    hjp Formula Junior

    Feb 23, 2013
    591
    Kansas City, Mo.
    Full Name:
    Jerry Peterson
    You say "should be". Can you confirm the lights inside the STOP and REC buttons are activated by the ignition switch and do not require the lights to be on for them to be on? IE, they are independent of both the light switch and dimmer and only turn on when pushed down?
     
  4. m.stojanovic

    m.stojanovic F1 Rookie
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    Dec 22, 2011
    3,288
    Serbia - Niš
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    Miroljub Stojanovic
    The STOP and REC buttons are mechanical switches with a small bulb behind to indicate the switch position, on & off. Therefore, you need these indicator lights to operate irrespective of whether the car lights are on or off otherwise you will not know the switch position during the day. If the small bulbs burn, the switch will still operate. If the bulbs are good but do not light up, it means:

    Either that there is no power coming to the switches (if the bulbs are directly powered by the switches; I think they are as I can see (on the pictures) 3 legs on these switches - 2 to switch whatever they are switching and one for the bulb), or

    If there is power coming to the switches but the bulbs do not light up, it means that either the part of the switch that lights up the bulb is faulty or that there is problem with the circuit board (this would be in the case the bulbs are not powered directly by the switches but by the circuit board).

    This is about all I can contribute as I have not had any experience with the 355 but I have had experience with switches with similar functions (and containing small bulbs) on other cars.
     
  5. taz355

    taz355 F1 Veteran
    Owner Silver Subscribed

    Feb 18, 2008
    6,016
    Indio Ca/ Alberta
    Full Name:
    Grant
    Jerry went through all this when i changed mine too Led. Go to the other site and Dave has a video posted. Its very good and explains it all. To answer your question they are quite dim when not pushed and quite bright when pushed. You should not have to change anything. They look off when out during daylight but they are dimmly lit when its dark.
     
  6. taz355

    taz355 F1 Veteran
    Owner Silver Subscribed

    Feb 18, 2008
    6,016
    Indio Ca/ Alberta
    Full Name:
    Grant
    Actually i also changed the stop and recirc with leds as well and blue socks.
     
  7. hjp

    hjp Formula Junior

    Feb 23, 2013
    591
    Kansas City, Mo.
    Full Name:
    Jerry Peterson
    Thanks Grant.
     

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