Brilliant idea needed!!!

[Geocacher]

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?????

 

[Anno Siegel]

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

 

[Meindert Sprang]

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

 

[Keith Williams]

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.

 

[Tim Wescott]

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.

 

[Fred Bloggs]

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????

 

[Fred Bartoli]

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.

 

[Geocacher]

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"

 

[Jim Thompson]

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

 

[Fred Bartoli]

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

 

[Adrian Tuddenham]

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! [...]

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

Get rid of the computer. It's probably less reliable than the LEDs
anyway.

 

[Geocacher]

We cannot 'play' with the computer system aboard the truck/tractor, hence
this enquiry. The solution must be attached to the trailer wiring in such a
way that the truck's system is satisfied that the lights are functional.

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! [...]

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

Get rid of the computer. It's probably less reliable than the LEDs
anyway.

 

[Jim Thompson]

We cannot 'play' with the computer system aboard the truck/tractor, hence
this enquiry. The solution must be attached to the trailer wiring in such a
way that the truck's system is satisfied that the lights are functional.

Not clear what you mean. Is "pulse" a VOLTAGE pulse and you measure
the current?

CURRENT pulse?

[...]

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

Get rid of the computer. It's probably less reliable than the LEDs
anyway.

...Jim Thompson

 

[Frank Bemelman]

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

I don't know. Can the current sensor (resistor?) be replaced, does
the fix only fix the disco behaviour, or does it also fix the
annoying error message?

Perhaps a switcher could be used to make the LED units work at
a much lower voltage, drawing a higher current. The remaining
voltage could run a step-up switcher to dump that energy back
into the battery.

 

[martin griffith]

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?????

Look up CAN bus, seems to be the indusrty standard. You need a micro
in the LED array, that can talk to the vehicle


martin

 

[Thomas Magma]

Do you know what the old tail lights current draw is vs. the new LED ones?
Is it 12VDC?

We cannot 'play' with the computer system aboard the truck/tractor, hence
this enquiry. The solution must be attached to the trailer wiring in such
a way that the truck's system is satisfied that the lights are functional.

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! [...]

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

Get rid of the computer. It's probably less reliable than the LEDs
anyway.

 

[Rich Grise]

We cannot 'play' with the computer system aboard the truck/tractor, hence
this enquiry. The solution must be attached to the trailer wiring in such a
way that the truck's system is satisfied that the lights are functional.

Give each LED in the array its own dropping resistor, and run all of
those LED/R strings in parallel. Use enough of them, at enough current,
so the total current is over the threshold. LEDs _do_ take _some_
current, you know. ;-)

Good Luck!
Rich

 

[Genome]

Time for a nice cuddly sleep in my nice cuddly bed.

DNA

 

[Thomas Magma]

OK here is my "brilliant idea" of the day. A resistor that is in series
with a polyfuse and then both in parallel with the LED lamp. This will shunt
the appropriate amount of current to fool the computer into thinking it's
drawing the right amount of current, then the polyfuse will trip before the
resistor has time to heat up. The polyfuse will stay open until the voltage
is removed. So you could probably get away with a small and cheap half watt
resistor.

Here is a link to polyfuses:
http://wickman-fuses.com/download/ptcappnote.pdf

Good luck.
Thomas

We cannot 'play' with the computer system aboard the truck/tractor, hence
this enquiry. The solution must be attached to the trailer wiring in such
a way that the truck's system is satisfied that the lights are functional.

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! [...]

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

Get rid of the computer. It's probably less reliable than the LEDs
anyway.

 

[petrus bitbyter]

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.

This is the place for some brillant questions. How often is that pulse send?
How long does is last? What current does it expect? How much do the LEDs
take? Is the voltage of that pulse the same as the normal operating voltage?
Is that 12V or 24V or other? Is that pulse also send when the lights are on?

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!

Why can't you keep that lights on? Or do they continue to simulate that
disco? What's the flash rate?

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.

Why? I've done that kind of things some more times. It's obvious that the
computer is to old to recognise the LED assemblies but apparently a
modification of it - let alone a new one - is more expensive then the bulbs
or resistors. I feel with you that it does not satisfy the technician but
economics rules you know.

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.

Well, telling the computer requires a current high enough to make it think
it sees incandescent bulbs. Bulbs or resistors come first into mind as you
already know. You can circumvent it only if you have acces to the inside of
the measuring system. It's almost sure that somewhere inside is a small
resistor in the pulse circuit, used to measure the current by measuring the
voltage accross it. If you can replace that resistor by a larger one, the
voltage accross it will increase so the system will "see" more current.

Another approach is to provide the bleeding resistor only when the computer
sends the measuring pulse. That's why I asked so many questions above. When
the pulse comes, the resistor is switched on by a transistor, a timer keeps
it on as long as the pulse lasts and switches it of afterwards. It's some
simple classical electronics once you know how to detect the start of that
measuring pulse.

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

Can't call that innovative. It's stretching the lifetime of an otherwise
obsolete computer system. Can nevertheless be attractive.

petrus bitbyter