LED light issue

[humphshumphs]

Not on my 75 Tourer..... but on my trailer

The towbar electrics on my tourer are through a bypass relay and it has a sounder (as required) to 'remind' me that the indicators are working.

All works fine when I checked it with the works trailer board (normal lights), but as my trailer has LED lights, it doesn't sound.... so do I need to add resistors to the trailer LEDs so the bypass relay can 'see' them???

If I do need to add resistors, can I fit them in-line in the cabling (I re-cabled the trailer so can easily add them), but what value resistor/wattage/etc., do I need.

Thanks in advance oh knowledgeable ones

[T-Cut]

Presumably, the trailer relay senses the bulb loading, a bit like the blown bulb monitoring (CANbus) system. If so, you need to add some ballast to the LEDs of fit CANbus friendly versions. I'd have thought the latter is much easier to do. However, if you wnt to modify the existing wiring yourself, the resistors should be wired in parallel with the bulbs. Something like this:



As to resistance value and wattage, the theory has it that you should replicate the equivalent filament bulb on both counts. That can mean quite hefty and therefore expensive resistors. My own tests on doing this suggests that the CANbus test is much more forgiving than the theory and a resistor of considerably less load is OK. However, LED indicators are not so easy. They usually need the theoretical loads and therefore generate a lot of heat (about 20watts per lamp). But it's still a chore unless you have no option with the LED lamps.

TC

[humphshumphs]

Originally Posted by T-Cut

Presumably, the trailer relay senses the bulb loading, a bit like the blown bulb monitoring (CANbus) system. If so, you need to add some ballast to the LEDs of fit CANbus friendly versions. I'd have thought the latter is much easier to do. However, if you wnt to modify the existing wiring yourself, the resistors should be wired in parallel with the bulbs. Something like this:



As to resistance value and wattage, the theory has it that you should replicate the equivalent filament bulb on both counts. That can mean quite hefty and therefore expensive resistors. My own tests on doing this suggests that the CANbus test is much more forgiving than the theory and a resistor of considerably less load is OK. However, LED indicators are not so easy. They usually need the theoretical loads and therefore generate a lot of heat (about 20watts per lamp). But it's still a chore unless you have no option with the LED lamps.

TC

The trailer light units are a 'fixed unit' so I can't change the lights.... but can easily add resistors...

Thanks

[T-Cut]

If it's just the indicator system that's unhappy, I'd suggest buying some of those high wattage wirewound resistors from eBay. There are dozens on offer.

eBay: http://www.ebay.co.uk/sch/i.html?_fr...stors&_sacat=0

Wire them in as I indicated (!) earlier and mount them on a heat sink and with plenty of cooling air around.

TC

[humphshumphs]

Originally Posted by T-Cut

If it's just the indicator system that's unhappy, I'd suggest buying some of those high wattage wirewound resistors from eBay. There are dozens on offer.

eBay: http://www.ebay.co.uk/sch/i.html?_fr...stors&_sacat=0

Wire them in as I indicated (!) earlier and mount them on a heat sink and with plenty of cooling air around.

TC

Cheers for that.... Have just ordered a couple and will let you know when they arrive and are fitted