Problems with LEDs for Instrument Cluster Indicator Lights

When I converted my 1982 308GTSi to LED dash and all running lights…. replacing the blinker relay to an LED type worked.

 

Waymar is right change the relay for the blinkers to fix hyper flash ( passenger side ) I changed all instruments to led but not the warning lights as there is no reason because the are not on a lot also LEDs only work one way.to pull the cluster is not a big deal steering wheel off 2 screws and pull forward to change the bulbs test all light before you put it back

 

Brian,

I just did this and here are a few of my conclusions. This was on a '77 so some things may be different on a later model.

1. The "Brake failure/High beam/Parking brake" string is wired with a + ground to the bulb sockets. The BA9s LEDs I used were polarity sensitive so I swapped the wire connections (soldering required) on the High beam socket. I left the Brake failure and Parking brake they way they were and with incandescent bulbs because LEDs in those two were too bright for me.
2. The 4 dash indicator bulbs have a different type of wedge connector than the ones in the speedo. The speedo sockets have the + and- on the same side but the dash indicator sockets have the + on one side and the - on the other. So a wedge bulb with both contacts on one side wont work. That is probably why your cabin fan fuse is blowing.
3. So, I left the 4 dash indicator lights, seatbelt light, Brake failure light, and Parking brake light incandescent because honestly, all of them were too bright for my taste with LED.

I love being able to see everything at night now! I would also recommend pulling all the bezels off and cleaning the lenses. Unbelievable the difference! It takes quite a bit of time and is tedious work, but well worth it.

Greg

 

LEDs require a LED flasher for the dash blinkers and turn signals.

 

LED's don't run on the same voltage as bulbs. Normally 5.5 volts. This is why in many cases of using LED's you need an IC to bring down the voltage. Also LED's are not "on" all the time. They are turned on and off so quickly you can't see it. Its called multiplexing. And that's how you get "dimming". In a bulb you turn down the voltage or current. With an LED you change the duty cycle time of "on" and "off" to make it appear "dim". Again, you need a circuit to do that. LED's also use a lot less current than a light bulb.

You can run some LED types off straight DC but the voltage should be correct, or at least close enough.

Not sure exactly about those two bulbs you mention but it may be because they work by getting the power directly from those devices at 12V.

 

You can buy a LED flasher on Amazon for the blinking lights. No led for alternator, only bulb. Bulb lets current flow both ways, led does not.

 

Exactly. People think LED's are just little bulbs. In reality they are electronic solid state circuits that generate light under certain circumstances.

 

The flasher I use.
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The advantage to putting RED LED in the rear brake lights and Amber/Yellow LED in the rear turn signal will be how much brighter the rear brake and turn signals will be. A good safety feature.
I kept the regular bulbs in the front lights.

Dash instruments are now easy to read at night with LEDs.

 

No harm to the system. The stock flasher relay should work fine with just the LED dash indicators. When you do get around to changing out the turn signal lamps (bulbs), then you will need to change the flasher relay to a suitable unit as suggested above.

 

This is something I would like to do on my 328 so I'm glad it worked out!

 

Good day All,

I wanted to clarify a few of the technical items commented above:

LEDs are not all the same and depending upon the component can be comprised of a single LED device or several wired in series or in parallel. Multiple individual LEDs wired in series/parallel will have different drive needs in terms of current and voltage. The bottom line do not assume every LED's current/voltage needs are the same no matter their physical size.

Given my statement above, an LED part's minimum voltage will vary ... and can vary by a lot. For a single LED, its voltage can be as low as around 2V... but for an LED Assembly comprised of LEDs wired in series/parallel, the minimum voltage can be much higher... 40V or more. I say again, make no assumptions as to the LED's minimum voltage, as too high a voltage can easily cause an LED to fail much sooner than it should.

LEDs are driven differently than incandescent lights in that LEDs are driven by current whereas Incandescents are driven by voltage. In older Auto applications the dimmer control generates a variable output voltage... which varies the light output of these older incandescent bulbs. Connecting a LED bulb to these old dimmers (like those used on older Ferraris), the light output will vary a little and then turn off... because the resulting output voltage is lower than the bias or forward voltage needed by the LED bulb. Varying the LED light out is done using a technique called Pulse Width Modulation (PWM), which was described in the posted comment in that it is a series of On and Off Pulses. However, the total time of the On and Off Pulse is constant... only the duration of the respective On or Off Pulse will change. Secondly, LED light output is not perceived linearly by the human eye, but rather follows a somewhat log curve. So... if you reduce the LED resulting drive current by 50%, the LED light output will be 50%... but the human eye will NOT see a 50% reduction in light output, but something much less. Sophisticated LED dimmer circuits will take this into account and in doing so the human eye will see a linear proportionate change in the light output level.

As for driving LEDs... in small and simple applications involving a single or a few LEDs, simply placing a resistor in series with the LED and the driving voltage will create a rudimentary current source and so the LED will function. However, any variation in the voltage will affect the current and thus the LED light output. The second issue with this simple current source is that there are no protections from abnormal voltage transients or spikes in voltages... which if high enough can electrically stress the LED causing it to fail immediately or reduce the LED's lifetime dramatically. The third issue is if additional LEDs are adding in series or in parallel, then simple current source's current output will change... which can cause all sorts of issues. Most inexpensive auto LED bulbs simply use a resistor in series with LED component resulting in a polarity sensitive bulb along with LED output level variation. Better and superior auto LED bulbs will use a current source semiconductor and these LED bulbs will have more consistent light output and typically longer lifetimes. The reason why most LED bulbs manufacturers do not use a dedicated current source device is because of cost (more parts + more parts to assemble), but also because the additional components adds to the physical size which may not be the same as the original incandescent bulb size.... remember that these LED bulbs have to fit into the same size cavity as the original bulbs.

Lastly, LEDs do consume less power... but have a much higher heat density. If a LED assembly is not designed to accommodate a LED's thermal needs, the LED will fail significantly sooner than it should. In general these LED thermal concerns are much less of an issue for the lower light output LED bulbs like those used in auto dash lights... but not always, as some LED Bulb vendors over drive the LED which increases the LED temp and so these designs fail in short time frames. As an extreme example high brightness LEDs like those used in Auto Headlights, warehouse lighting, etc these LEDs can have a case termps of 90C (194F) and a surface temps of 140C (284F)... and at these temps it is imperative that proper thermodynamic design be done... otherwise these LEDs will fail in a very short amount of time.

Cheers,

Sam

 

Most of your questions have been answered comprehensively, but I will add a bit of explanation. Incandescent indicator circuits use a thermal flasher - the current runs through a heating coil, which heats a bimetallic strip to open and close the circuit. When a bulb drops out, the current load changes, and the circuit opens and closes faster - a simple method to alert you to a lost bulb. LEDs have extremely low current draw, and so the flasher cycles way too fast (or not at all) - hence the need for an electronic one. The alternator light is wired in series to what is called the exciter - 12V is fed to the bulb, and it grounds on the exciter terminal of the alternator. This is needed for an alternator of that vintage to charge. Once it starts charging, it applies 12V to the exciter terminal, so there is no voltage drop through the alternator light, and it goes out. So the alternator light can only be an incandescent bulb.

 

I know this is not directly related to our cars but I have found that LED bulbs in our house seem to have a SHORTER life span than incandescent bulbs! I am not impressed!

 

Ditto that. I have also found that LED bulbs in our house do not last nearly as long as advertised.
While driving, I also notice new vehicles with LED lights that have failed. That should not be happening. Consequently, I am not considering replacing any of the bulbs in my 328.

 

Good day Mike,

Sadly, this is not uncommon. That said, a properly designed LED bulb will last a very long time. One of my first LED designs has had zero failures in 9 years of 24/7 operation with a statistical estimated lifetime is around 30 years.
There are many reasons why LED lights fail and in most cases comes down to the following:

1. Minimal to no thermal design considerations for the LEDs and/or LED fixture

2. Lack of a proper LED electrical design:
- insufficient or non existent electrical design to address input voltage/power electrical anomolies (pump bumps, lightning spikes, etc)
- incorrect support component specifications (some vendors design in the bare minimum spec'd parts, etc)
- use of low quality electrical components

Now, for the typical household "bulb" which uses a "E26 " base (the standard threaded base that most households use or used to use)... the reason for the failures are because of the above, but are made worse because the LED replacement has to be maintain the original mechanical/form factor as the original bulbs. The original bulbs had little space for all of the necessary electronics needed for a long term quality LED light. Secondly, the original design had limited mechanisms to deal with the LED's thermal issues. Thirdly... and this applies to a lot of LED lights... customers simply are not prepared to pay for a quality product. LED lighting has become commodity based and so most customers shop based upon price which forces a race to the bottom (give up quality to reduce price) by manufacturers. I have tried ad nausem to convince numerous customers of the above, but they were singularly focused on price... and so even the best of what is available will last 3-5 years at best. The higher the LED brightness and/or power levels will typically see a marked reduction i lifetimes. Sadly, you can only bring a horse to water...

There is a lot more I can say, but I am sure I have bored you all way too much already.

Cheers,

Sam