Strange LED problem.

[steelroe]

I have just fitted LED's bulbs all, everything works lovely except that when I press the brake pedal now the dash light, ashtray etc. come on. Aslo the buzzer for the lights left on comes on when I press the brake pedal.

Anyone ever come across this before I start to investigate further.
If I remove the LED's all is fine.

[steelroe]

Only thing i can think of is that given the Brake and Park are the same bulb one of them must have a short somewhere.

Time to investigate further.

[kevinod]

One of those weird problems, good job you know what was changed to narrow it down!

[colm_mcm]

sounds like one of the LED combination bulbs for the brake/parking light is not fitted correctly, and is shorting the two circuits,

remove 1 bulb at a time and see if the problem disappears.

[steelroe]

Had a good look at these this evening and the lamps are fitted correctly. But the is a design flaw in the units.

The units consist of 24 LED's in series with the appropriate resistor (s). When the parks are turned on the power is supplied through 1 resistor and the lamps come on dim.
When the brake is applied the power is supplied to the same leg of the lED's but through a diff value resistor, and they light up much brighter.

Now here is the problem.

They have fitted a blocking diode on the negative leg of the lamp to prevent damage if volltoage is supplied to the negative leg. This is correct.

But there is no blocking diode fitted to the supplly leg of the "PARK" circuit, thus when the brake is applied, voltage is sent up the "PARK" circuit through a resistor and all of the dash lights come on as they are part of the same circuit.

Solution.

I will cut the each of the park supply wire and solder in a blocking diode, this will allow voltage to travel in one direction. Will update once I have this done.

All this aside the units are a hugh improvement over the standard bulbs!!

[mcgon1979]

good solution man, well explained. Did it go well?

[steelroe]

Soldered in a blocking diode to each of the tail light supply wires (near the connector for convienence). This way you only have to use 2 diodes, versus 4 if you godirect to theback of the lamp.

Works perfect

[kevinod]

Nice one! Any before & after pics?

[steelroe]

Will try and get some before and after pics this evening. in the meantime pics here of the LED's at night. Very bright.