T

tomjdale

Member
My 97 V8 Disco has had the newer TD5 style rear (upper) light clusters fitted.

Since this all the indicators now flash double time? They work ok when my caravan is attached and the electrics connected, but not solo.

Could this be some sort of earth problem? I have checked all the bulbs and they are correct.

Any ideas?
 
I'd check for earth fault, relay connection, bad connection somewhere, wired wrongly.
 
When you say, "I have checked all the bulbs and they are correct", do you mean they all work? Flashing fast usually means you've got a bulb out. Connecting a trailer/caravan would increase the load on the circuit and make it flash at the right rate. (I think)
 
When it is connected to the caravan and is flashing, does the trailer warning flasher in the dash flash?

With ONE bulb flashing it should flash in double quick time.

With TWO bulbs flashing is should flash once a second

With THREE bulbs flashing it shoukld flash normally once a secaond AND flash the wee trailer light in the dash.

Have you by any chance fitted 5 watt bulbs or 24 volt bulbs?

Flasher bulbs should be 12 volts 21 watts, and nothing else.

CharlesY
 
I'm with CharlesY on this. It sounds like a lack of resisitance has been detected. Have you fitted L.E.D. bulbs without the resistors?
 
The little trailer indicator on the dash does not flash when connected to the van.

I think the problem is due to the TD5 rear lights being fitted. The old lights would have had an extra indicator on each side, but this extra light on each side is missing with the TD5 rear lights. Could adding some sort of resistor help?
 
Yes. When fitting LED bulbs to indicators there is a resistor that needs to be fitted to make them flash at the normal speed as they use much less current than a normal bulb. Fitting resisitors should sort out your problem.
 
hmmmmmmmm........ very interesting to know, my BMW has LED rear lights fitted and the onboard computer always sais "tail light failure/brake light failure" so i guess i need to fit a resistor to it it before i sell it then - cheers charlsey - are they expensive and how do i find out which type i need?
 
you could always buy a relay what is suitable for led bulbs. as everyone says its the resistance what is the problem.
 
CharlesY said:
Just fit the correct plain old bulbs and keep the fancy ones for a Landy!

CharlesY
Click to expand...

I would if i could but i cant, its the entire clusters that i would have to replace (theyre built in E46 M3 "look" LED ones). Ive got clear lights in the Landy bumpers and wouldnt mind putting the LEDs in them for peice of mind as I believe LEDs last longer than halogen bulbs and so i wouldnt have to replace them so often - or get pulled pulled by local plod for a failed brake light and them to decide to check my motor out to see if everything is road legal :( Which it IS of course;):)
 
could you not go to an electronic store such as MAPLINS or TANDYS and ask them which resistor they would recommend if you explain to them what the problem was? would it be possible to use a relay off another vehicle that uses LED bulbs?
i put LED indicators on my motorcycle and i had the same problem but got round it by using a normal bulb as a resistor and just moving it out of sight so in effect i had three bulbs on each side but not sure whether this would work for you.
 
You need a big resistor for the purposes of slowing the flash rate down, a wire wound type. Or you can fit one for each side under the bonnet strapped to the body to create a heat sink.

A 21W lamp presents a resistance of around 7ohms to the circuit, these are wired in parallel so the total circuit load = 1/Rt = 1/R1 + 1/R2 + 1/R3...

There are 3 x 21W and 1 x 5W indicator lamps per side, so the relay will be 'looking' for just under 3 ohms.

If possible you need to measure the resistance of the circuit you have now created, either measuring from the flasher relay or find the resistance of one of your LED lamps and work it out from there...

Then you need to subtract you resistance from the expected load (2.916ohms) this will tell you the resistance value you need to add to the circuit.

Next you need to know how much power will be dissipated in the resistor. P = V x I, we know V = 12 but we need to work out I, I = V(12)/R(2.916 or whatever yours will end up when a preferred value resistor is added!) = 4.115W, so your resistor will need to be rated at more than 4W.

These are ideal... 10 Watt Wirewound Resistor > Maplin

HTH
Lerk
 
Or you could do the really simple job of fitting a bulbholder and bulb. somewhere out of sight. and it'll act as a resistor and solve the problem.
 
I have thought about adding an extra bulb in a holder, but the resistor idea sounds better, if I can get the right one?

Would the one one the Maplins link coded H3R3 work then lekr?
 
You really need to check first, but it should be about right...

Don't forget you'll need two - one for either sides indicator circuit.

For the price of em i'd get a couple of values either way too, you can then try the suck it and see method!
 
Finally got round to getting the resistors suggested, but still having no luck.

I tried the following three things,

1. Adding the resistor in series between on the front indicator - no chenage
2. Adding a second bulb on the front indicator (in series again) - no change
3. Adding a second bulb and the resistor in series - No indicator light at all!

No I am confused, could I just get some sort of alternative indicator relay?
 
tomjdale said:
Finally got round to getting the resistors suggested, but still having no luck.

I tried the following three things,

1. Adding the resistor in series between on the front indicator - no chenage
2. Adding a second bulb on the front indicator (in series again) - no change
3. Adding a second bulb and the resistor in series - No indicator light at all!

No I am confused, could I just get some sort of alternative indicator relay?
Click to expand...

First off, assuming you have the correct resisitors, you will need one for every bulb you have replaced. (Unless you have opted for one resisitor with a greater overall resistance).

Secondly, If memory serves me correctly (it was about 3 years ago that I did mine) The resistors need to be wired in parallel to each of the bulb holders.
 
My lights flash fast when the trailer is not connected. I have just replaced my relay with one I bought from Ebay which has 4 spade connectors instead of 3. I'm guessing that if the rear clusters with indicators were fitted it would have been ok. Is it going to cause any long term problems if they flash fast? Does it really matter? I do use a trailer most of the time and they work normally so I can't see it's much of a problem. Could it cause the relay to overheat?
 
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