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Electrical gremlins related to ignition light
petroldiaries - 19/3/18 at 06:52 PM

I hit some electrical gremlins in Episode 7 of my Westfield restore diary (See link below). I'm fitting replacement LED dash lights as the old ones have seen better days, also I'm fitting new switches as these have started to discolour and are showing signs of corrosion on the back. I've been contacted by someone whose recommend I check the ignition switch as he's seen similar engine running down issues when jiggling the wires, anyone else seen similar?

https://youtu.be/B12DvmgrSSs


If anyone can make use of a full set of old switches let me know, free to anyone who wants on here.


petroldiaries - 19/3/18 at 07:00 PM

It probably helps if I post a picture;o)


CosKev3 - 19/3/18 at 07:03 PM

Just be aware you will need to do some extra fiddling about with the wiring if you intend to use a LED instead of a filament bulb for the ignition light


petroldiaries - 19/3/18 at 07:07 PM

quote:
Originally posted by CosKev3
Just be aware you will need to do some extra fiddling about with the wiring if you intend to use a LED instead of a filament bulb for the ignition light


Erm ok I just assumed i could do a like for like swap, is there more to it?


daviep - 19/3/18 at 07:36 PM

quote:
Originally posted by petroldiaries
quote:
Originally posted by CosKev3
Just be aware you will need to do some extra fiddling about with the wiring if you intend to use a LED instead of a filament bulb for the ignition light


Erm ok I just assumed i could do a like for like swap, is there more to it?


Charging circuit may not work with LED installed instead of filament bulb, LED may not draw enough current through the alternator excitation circuit to start charging process. You can install an additional hidden bulb or resistor to make it work properly.


big_wasa - 19/3/18 at 07:49 PM

You could treat your self to a bright 6 display.


starterman - 19/3/18 at 08:08 PM

Daviep is right in what he says about an LED ignition light not working. Put a resistor in the line and it will be ok.

Cheers
Mike


petroldiaries - 19/3/18 at 08:58 PM

Wow thanks for the great advice guys, glad I posted on here otherwise could have been chasing my tail again.


CosKev3 - 19/3/18 at 09:19 PM

Yeah as above ref exitation,your new alternator would not be charging with just a LED warning light


gremlin1234 - 19/3/18 at 09:34 PM

quote:
Originally posted by starterman
Daviep is right in what he says about an LED ignition light not working. Put a resistor in the line and it will be ok.

Cheers
Mike
the resister should be in parallel not series (I am sure you know that, but to make it explicit for others ;-)

other thing to note, led's are 'directional' ie have pos and neg, filament bulbs don't care

edit sp

[Edited on 19/3/18 by gremlin1234]


petroldiaries - 19/3/18 at 09:35 PM

quote:
Originally posted by CosKev3
Yeah as above ref exitation,your new alternator would not be charging with just a LED warning light


Cheers mate!!! I like the hidden bulb idea


daviep - 21/3/18 at 07:37 PM

quote:
Originally posted by gremlin1234
quote:
Originally posted by starterman
Daviep is right in what he says about an LED ignition light not working. Put a resistor in the line and it will be ok.

Cheers
Mike
the resister should be in parallel not series (I am sure you know that, but to make it explicit for others ;-)

[Edited on 19/3/18 by gremlin1234]


TBH I have never given it any thought, what's the reason it must be in parallel? Off the top of my head I can't think why it makes any difference.

Cheers
Davie


starterman - 21/3/18 at 08:18 PM

quote:
Originally posted by gremlin1234
quote:
Originally posted by starterman
Daviep is right in what he says about an LED ignition light not working. Put a resistor in the line and it will be ok.

Cheers
Mike
the resister should be in parallel not series (I am sure you know that, but to make it explicit for others ;-)

other thing to note, led's are 'directional' ie have pos and neg, filament bulbs don't care

edit sp

[Edited on 19/3/18 by gremlin1234]


Just so happens I know about stuff like that, I have been known to repair the odd 20 or 30 alternators and associated stuff a week lol


daviep - 21/3/18 at 08:41 PM

I'm not doubting you, I wanted to know the actual technical reason to increase my understanding.

Cheers
Davie


gremlin1234 - 21/3/18 at 09:51 PM

quote:
Originally posted by daviep


TBH I have never given it any thought, what's the reason it must be in parallel? Off the top of my head I can't think why it makes any difference.

Cheers
Davie
the alternator requires a reasonably small current though the circuit.
a 2.4W 12V bulb is 200mA
led, with is resistor < 10mA
in series these two would only pass the led current. (actually a tiny fraction less, but negligibly so ) ~5mA
in parallel, the current would be the two added together ~ 205mA


daviep - 21/3/18 at 10:47 PM

Thanks, that makes perfect sense I was having a complete brain fart, obviously the resistor in series reduces the current when in fact we are trying to increase it.

Much apppreciated
Davie