Brilliant idea needed!!!

I work in the trailer manufacturing business.
We use LED tail-light clusters.
The modern truck/tractors utilise a computer system to perform diagnostics
on various systems within the rig. One of these is the lighting system.
A pulse is sent to each tail light, the system monitoring the current. If
there is current flow, it is assumed the incandescent globes are OK.

Unfortunately, the LED lamps draw such a small amount of current that the
computer does not see a "filament" and flags a major fault on the truck
dashboard. In addition to the error message, the system continues to send
curent pulss in the forlorn hope that things at the rear of the rig have
improved. This causes the entire suite of LED lamps to flash like a
low-class disco!

There are ways around it. Some manufacturers have placed incandescent globes
in parallel with the LED lamps, others have used high wattage resistors.
Neither is acceptable for obvious reasons.

There must be a way to "tell" the computer that the LED lamps are fine by
emulating the current drawn by an incandescent globe, without using the
solutions noted above.

Do any of you outstandingly brilliant contributors have any novel and
innovative ideas?????

Geocacher <(E-Mail Removed)> wrote in sci.electronics.design:
> I work in the trailer manufacturing business.
> We use LED tail-light clusters.
> The modern truck/tractors utilise a computer system to perform diagnostics
> on various systems within the rig. One of these is the lighting system.
> A pulse is sent to each tail light, the system monitoring the current. If
> there is current flow, it is assumed the incandescent globes are OK.
>
> Unfortunately, the LED lamps draw such a small amount of current that the
> computer does not see a "filament" and flags a major fault on the truck
> dashboard. In addition to the error message, the system continues to send
> curent pulss in the forlorn hope that things at the rear of the rig have
> improved. This causes the entire suite of LED lamps to flash like a
> low-class disco!
>
> There are ways around it. Some manufacturers have placed incandescent globes
> in parallel with the LED lamps, others have used high wattage resistors.
> Neither is acceptable for obvious reasons.
>
> There must be a way to "tell" the computer that the LED lamps are fine by
> emulating the current drawn by an incandescent globe, without using the
> solutions noted above.

The test you describe is applicable while the tail-lights are off. Does
the diagnostic system permanently monitor the current when they are
switched on? If so, I don't see a simple solution except re-calibrating
the current the diagnostic system expects.

For the test you describe you could use the parallel resistor, but switch
it off after a second or so of power. The duration must be long enough
to cover the test pulse and short enough not to cause excess power
consumption in the long run. A more sophisticated solution would check
if the LED array draws the expected current and only add the parallel
resistor if it does.

Anno
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" Geocacher" <(E-Mail Removed)> wrote in message
news:dgu6ht$g24$(E-Mail Removed)...
> I work in the trailer manufacturing business.
> We use LED tail-light clusters.
> The modern truck/tractors utilise a computer system to perform diagnostics
> on various systems within the rig. One of these is the lighting system.
> A pulse is sent to each tail light, the system monitoring the current. If
> there is current flow, it is assumed the incandescent globes are OK.
>
> Unfortunately, the LED lamps draw such a small amount of current that the
> computer does not see a "filament" and flags a major fault on the truck
> dashboard. In addition to the error message, the system continues to send
> curent pulss in the forlorn hope that things at the rear of the rig have
> improved. This causes the entire suite of LED lamps to flash like a
> low-class disco!

The first thing that comes to mind is to place a lage capacitor (1000uF?)
across the LEDS, to draw a high current pulse during the test, providing the
test is short enough. But I suspect this will flash the lights as well since
the cap is discharged through the LED's.

Meindert

In article <(E-Mail Removed)>,
(E-Mail Removed) says...
> " Geocacher" <(E-Mail Removed)> wrote in message
> news:dgu6ht$g24$(E-Mail Removed)...
> > I work in the trailer manufacturing business.
> > We use LED tail-light clusters.
> > The modern truck/tractors utilise a computer system to perform diagnostics
> > on various systems within the rig. One of these is the lighting system.
> > A pulse is sent to each tail light, the system monitoring the current. If
> > there is current flow, it is assumed the incandescent globes are OK.
> >
> > Unfortunately, the LED lamps draw such a small amount of current that the
> > computer does not see a "filament" and flags a major fault on the truck
> > dashboard. In addition to the error message, the system continues to send
> > curent pulss in the forlorn hope that things at the rear of the rig have
> > improved. This causes the entire suite of LED lamps to flash like a
> > low-class disco!
>
> The first thing that comes to mind is to place a lage capacitor (1000uF?)
> across the LEDS, to draw a high current pulse during the test, providing the
> test is short enough. But I suspect this will flash the lights as well since
> the cap is discharged through the LED's.

How about a diode in series with the cap to isolate the LEDs? Maybe a
resistor across the cap to discharge it since the LEDs won't.

--
Keith

Geocacher wrote:
> I work in the trailer manufacturing business.
> We use LED tail-light clusters.
> The modern truck/tractors utilise a computer system to perform diagnostics
> on various systems within the rig. One of these is the lighting system.
> A pulse is sent to each tail light, the system monitoring the current. If
> there is current flow, it is assumed the incandescent globes are OK.
>
> Unfortunately, the LED lamps draw such a small amount of current that the
> computer does not see a "filament" and flags a major fault on the truck
> dashboard. In addition to the error message, the system continues to send
> curent pulss in the forlorn hope that things at the rear of the rig have
> improved. This causes the entire suite of LED lamps to flash like a
> low-class disco!
>
> There are ways around it. Some manufacturers have placed incandescent globes
> in parallel with the LED lamps, others have used high wattage resistors.
> Neither is acceptable for obvious reasons.
>
> There must be a way to "tell" the computer that the LED lamps are fine by
> emulating the current drawn by an incandescent globe, without using the
> solutions noted above.
>
> Do any of you outstandingly brilliant contributors have any novel and
> innovative ideas?????
>
>
Eventually the computer manufacturers will get off their duffs and
correct _their_ problem. Call them up, tell them LED tail lights have
been on the market for years, and ask them which one of their
competitors does the job right.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Geocacher wrote:
> I work in the trailer manufacturing business.
> We use LED tail-light clusters.
> The modern truck/tractors utilise a computer system to perform diagnostics
> on various systems within the rig. One of these is the lighting system.
> A pulse is sent to each tail light, the system monitoring the current. If
> there is current flow, it is assumed the incandescent globes are OK.
>
> Unfortunately, the LED lamps draw such a small amount of current that the
> computer does not see a "filament" and flags a major fault on the truck
> dashboard. In addition to the error message, the system continues to send
> curent pulss in the forlorn hope that things at the rear of the rig have
> improved. This causes the entire suite of LED lamps to flash like a
> low-class disco!
>
> There are ways around it. Some manufacturers have placed incandescent globes
> in parallel with the LED lamps, others have used high wattage resistors.
> Neither is acceptable for obvious reasons.
>
> There must be a way to "tell" the computer that the LED lamps are fine by
> emulating the current drawn by an incandescent globe, without using the
> solutions noted above.
>
> Do any of you outstandingly brilliant contributors have any novel and
> innovative ideas?????
>
>

Easily and obviously fixed but how much do you want to pay for the
answer????

" Geocacher" <(E-Mail Removed)> a écrit dans le message de
news:dgu6ht$g24$(E-Mail Removed)...
> I work in the trailer manufacturing business.
> We use LED tail-light clusters.
> The modern truck/tractors utilise a computer system to perform diagnostics
> on various systems within the rig. One of these is the lighting system.
> A pulse is sent to each tail light, the system monitoring the current. If
> there is current flow, it is assumed the incandescent globes are OK.
>
> Unfortunately, the LED lamps draw such a small amount of current that the
> computer does not see a "filament" and flags a major fault on the truck
> dashboard. In addition to the error message, the system continues to send
> curent pulss in the forlorn hope that things at the rear of the rig have
> improved. This causes the entire suite of LED lamps to flash like a
> low-class disco!
>
> There are ways around it. Some manufacturers have placed incandescent
globes
> in parallel with the LED lamps, others have used high wattage resistors.
> Neither is acceptable for obvious reasons.
>
> There must be a way to "tell" the computer that the LED lamps are fine by
> emulating the current drawn by an incandescent globe, without using the
> solutions noted above.
>
> Do any of you outstandingly brilliant contributors have any novel and
> innovative ideas?????
>

You can have the information in about 50ms if you pay me the right price.


--
Thanks,
Fred.

The payment you request would be adequately supplied by the outright
admiration of your peers on this forum. They (me included) would bow our
heads in honour of the man who could fix the problem in 50mS!


"Fred Bartoli"
<fred._canxxxel_this_bartoli@RemoveThatAlso_free.f r_AndThisToo> wrote in
message news:4332d190$0$21208$(E-Mail Removed)...
>
> " Geocacher" <(E-Mail Removed)> a écrit dans le message de
> news:dgu6ht$g24$(E-Mail Removed)...
>> I work in the trailer manufacturing business.
>> We use LED tail-light clusters.
>> The modern truck/tractors utilise a computer system to perform
>> diagnostics
>> on various systems within the rig. One of these is the lighting system.
>> A pulse is sent to each tail light, the system monitoring the current. If
>> there is current flow, it is assumed the incandescent globes are OK.
>>
>> Unfortunately, the LED lamps draw such a small amount of current that the
>> computer does not see a "filament" and flags a major fault on the truck
>> dashboard. In addition to the error message, the system continues to send
>> curent pulss in the forlorn hope that things at the rear of the rig have
>> improved. This causes the entire suite of LED lamps to flash like a
>> low-class disco!
>>
>> There are ways around it. Some manufacturers have placed incandescent
> globes
>> in parallel with the LED lamps, others have used high wattage resistors.
>> Neither is acceptable for obvious reasons.
>>
>> There must be a way to "tell" the computer that the LED lamps are fine by
>> emulating the current drawn by an incandescent globe, without using the
>> solutions noted above.
>>
>> Do any of you outstandingly brilliant contributors have any novel and
>> innovative ideas?????
>>
>
> You can have the information in about 50ms if you pay me the right price.
>
>
> --
> Thanks,
> Fred.
>
>

On Thu, 22 Sep 2005 14:02:56 +0200, " Geocacher" <(E-Mail Removed)> wrote:

>I work in the trailer manufacturing business.
>We use LED tail-light clusters.
>The modern truck/tractors utilise a computer system to perform diagnostics
>on various systems within the rig. One of these is the lighting system.
>A pulse is sent to each tail light, the system monitoring the current. If
>there is current flow, it is assumed the incandescent globes are OK.
>
>Unfortunately, the LED lamps draw such a small amount of current that the
>computer does not see a "filament" and flags a major fault on the truck
>dashboard. In addition to the error message, the system continues to send
>curent pulss in the forlorn hope that things at the rear of the rig have
>improved. This causes the entire suite of LED lamps to flash like a
>low-class disco!
>
>There are ways around it. Some manufacturers have placed incandescent globes
>in parallel with the LED lamps, others have used high wattage resistors.
>Neither is acceptable for obvious reasons.
>
>There must be a way to "tell" the computer that the LED lamps are fine by
>emulating the current drawn by an incandescent globe, without using the
>solutions noted above.
>
>Do any of you outstandingly brilliant contributors have any novel and
>innovative ideas?????
>

The computer doesn't send the pulse, it instructs the "system" to send
the pulse and measure the response.

Change your algorithm, so the response is meaningful... maybe trickle
100uA and measure the voltage... LED's ARE junction devices, you know?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

" Geocacher" <(E-Mail Removed)> a écrit dans le message de
news:dguk7a$b53$(E-Mail Removed)...
> The payment you request would be adequately supplied by the outright
> admiration of your peers on this forum. They (me included) would bow our
> heads in honour of the man who could fix the problem in 50mS!
>
>

The answer was in the answer. Just find it :-)


--
Thanks,
Fred.