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Lighting query (Transport)

G

Geocacher

Jan 1, 1970
0
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?????
 
S

St. John Smythe

Jan 1, 1970
0
Geocacher said:
Do any of you outstandingly brilliant contributors have any novel and
innovative ideas?????

Instead of putting on a "blowout patch" (by kludging apparent current
draw at the lights), you should put the onus on the computer
manufacturer to get into the 21st century and provide you with a
retrofit. LEDs on trucks are no longer cutting edge technology.
 
G

Geocacher

Jan 1, 1970
0
Believe me we have had extensive discussions (arguments/shouting matches)
with the truck suppliers. I would imagine that the computer system sensing
program could be adjusted to suit, but no-one here (South Africa) is
prepared to even attempt a fix. I imagine it will happen, but it appears
that this will be later rather than sooner!
More and more of the modern trucks are fitted with these so-called
"intelligent" dashboards, but the importers are more interested in making
the sale and getting commission than trying to resolve the problem.
So ... the problem persists.
 
S

St. John Smythe

Jan 1, 1970
0
Geocacher said:
Believe me we have had extensive discussions (arguments/shouting matches)
with the truck suppliers. I would imagine that the computer system sensing
program could be adjusted to suit, but no-one here (South Africa) is
prepared to even attempt a fix. I imagine it will happen, but it appears
that this will be later rather than sooner!
More and more of the modern trucks are fitted with these so-called
"intelligent" dashboards, but the importers are more interested in making
the sale and getting commission than trying to resolve the problem.
So ... the problem persists.

Because the system is (presumably) sensing current flow, and the LEDs
don't flow enough current, the approach I would take would be to use a
power transistor, turned on by the smaller current flow through the
LEDs, to flow a large enough current to satisfy the computer. That's
fairly straightforward, and you should be able to find a local
electronics person to put something together for you. It might even be
marketable (hint).
 
M

Mike Berger

Jan 1, 1970
0
Actually the problem is exacerbated. They lose the value of
performing the diagnostics on the lights.
 
G

Geocacher

Jan 1, 1970
0
Mike's response is right on the money! "Fixing" the problem by additional
current-drawing devices (of whatever type) will negate the diagnostic
capabilities of the system.

Given that the truck suppliers won't let us tinker with their computer
(voids the warranty) there MUST be a method to solve this problem at the
trailer side!
 
C

CWatters

Jan 1, 1970
0
Geocacher said:
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.

One solution might be to fit a large capcitor in parallel with the LEDs.
That might work if the test pulse is short enough.
 
C

CWatters

Jan 1, 1970
0
CWatters said:
One solution might be to fit a large capcitor in parallel with the LEDs.
That might work if the test pulse is short enough.

or you could build a circuit that detects the test pulse and switches in a
dummy load briefly.
 
M

Mike Meakin

Jan 1, 1970
0
Gentlemen,

I have done this very thing for a major UK truck lighting supplier and it
wasn't easy. You're on the right lines about switching a dummy load in - BUT
you have to do it at the right time ! Different manufacturers use different
schemes - some single tests and some multiple tests and you have to find out
who does what and when they do it ?

I am not at liberty to 'reveal all' but please be assured it is possible. I
think another UK supplier has a smart electronic load available as an add on
for those using LED lighting. Will look up my notes and post link.
 
G

Geocacher

Jan 1, 1970
0
That's good news! I look forward to seeing the link / more information.
Thanks
 
M

Mike Meakin

Jan 1, 1970
0
The company is Britax
Web link:
http://www.britax-pmg.com/

Device is E07.00.24V & 12V - Smart Load Devices

Web site was not working correctly this morning so couldn't find link to
this product.
 
J

Jasen Betts

Jan 1, 1970
0
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?????

how is the current to the indicators measured?

if's a through-hole type hall-effect sensot put more turns of wire through
the hole. if it's a shunt resistor replace it with one of higher resistance.

otherwise you'd need to reprogram the computer.

Bye.
Jasen
 
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