Wiring issues with indicators and rear lights

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peterc
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Re: Wiring issues with the new LED rear lights

Post by peterc »

Nik
Not knowing what LED's you were testing but Spiyda confirm that the LEDs are a lot more efficient than bulbs, so even though there is more light, the total current with the indicators, brake light and rear light should be less than just a brake light bulb on its own.
Peter C
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peterc
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Re: Wiring issues with the new LED rear lights

Post by peterc »

Just checked the earthing points at the rear of the car together with the A frame and front of car and all no greater ohm reading than the test wire at 0.6 so not a lot wrong with earthing.
In tracing the pulsing supply to brake lights found that the input to the fuse box fluctuates in line with the flasher unit.
Must be feed back within the fuse/ relay area.
More tests tomorrow.
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peterc
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Re: Wiring issues with the new LED rear lights

Post by peterc »

First rule of any job that is not going totally satisfactory is to go back to square one.
What have you added or changed.
Having checked that the earthing points were good what about the actual connection of the wire to lug.
So cut off the new earthing lugs and remake using a better quality climping tool. Also for peace of mind take extra care to ensure that the insulation is clear of the crimping area.
The result is still a small fluctuation in intensity of the brake lights when the indicators are operating but meter now states only 0.4 volts.
So question to our more learned electrically savvy members is what voltage fluctuation (if any) would you expect to see when the indicators are working.
Visual affect on the brake lights is fairly minimal but is it correct?
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Roger King
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Re: Wiring issues with the new LED rear lights

Post by Roger King »

Erm... first rule of any electrical job is not to use crimped connections...
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peterc
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Re: Wiring issues with the new LED rear lights

Post by peterc »

Just one problem Roger.
The whole loom supplied by Gerry is all crimped connections.
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Paul Blore
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Re: Wiring issues with the new LED rear lights

Post by Paul Blore »

I'm inclined to agree with Roger. If I'm using crimp type connectors, I generally solder, rather than crimp them on.

With regard to the small voltage drop, while the LED's use much less power than conventional bulbs, the ones used in these light fittings are pretty hefty and may well cause a small voltage drop I would have thought. Do you get the same effect with the engine running?

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Karl
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Re: Wiring issues with the new LED rear lights

Post by Karl »

LED`s should work on a constant current source, not on a voltage source. Not knowing the circuit of the lamps I think they have a pre resistor in -line.
Still the difference in a car system 12 to 14 V will have the LED current change and with that the intensity. To have the intensity constant you must have a circuit that keeps the current through the LED absolutly constant.
As for the wiring, crimping is since many years standard in industrial applications and very good, using the correct material and tools. Do you find any soldered connections in modern cars with their miles of wiring?
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Roger King
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Re: Wiring issues with the new LED rear lights

Post by Roger King »

Karl wrote:...using the correct material and tools...
I don't know anyone who can replicate a robot production line quality standard. So many times I try to fix something electrical on a classic car, to find there's a rubbish crimped connection at fault. And... (hesitates to say it)... AC never used them...

Saw you in the distance at LMC Karl, but never got close enough to chat - see you at Silverstone?
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Re: Wiring issues with the new LED rear lights

Post by Paul Blore »

Karl wrote:LED`s should work on a constant current source, not on a voltage source. Not knowing the circuit of the lamps I think they have a pre resistor in -line.
Still the difference in a car system 12 to 14 V will have the LED current change and with that the intensity. To have the intensity constant you must have a circuit that keeps the current through the LED absolutly constant.
As for the wiring, crimping is since many years standard in industrial applications and very good, using the correct material and tools. Do you find any soldered connections in modern cars with their miles of wiring?
Assuming that the resistance isn't changing, a variation of voltage will cause a variation of current and vice versa.

Paul
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peterc
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Re: Wiring issues with the new LED rear lights

Post by peterc »

Thanks for comments to date guys
Some interesting reminders of the technical back ground to electricity.
In answer to Paul's question - yes it still has a 0.3 volt drop but of course centered around 14V ( 13.84 - 14.15)
Still thinking how the operation of the indicator circuit can upset the system other than a dodgy earth some where.
Chris has already stated that the entire LED set up only draws the equivalent of one filament type brake light bulb.
Peter C
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