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limey222
Michael Cubbon
Portland, OR
(129 posts)

Registered:
08/01/2015 12:55PM

Main British Car:
1969 MGB GM 3.4L V6

Engine warning light from 94 GM 3.4 PCM
Posted by: limey222
Date: September 01, 2015 07:04PM

A very simple question, can anyone see a reason why I can't use a small 12v red led pilot light to signal a fault condition? I am concerned about it having too low a resistance to ground unlike a conventional bulb.

See: [www.ebay.com]



Edited 1 time(s). Last edit at 09/01/2015 07:08PM by limey222.


kstevusa
kelly stevenson
Southern Middle Tennessee
(985 posts)

Registered:
10/25/2007 09:37AM

Main British Car:
2003 Jaguar XK8 Coupe 4.2L DOHC/ VVT / 6sp. AT

authors avatar
Re: Engine warning light from 94 GM 3.4 PCM
Posted by: kstevusa
Date: September 02, 2015 08:01AM

Should be OK, I used a orange LED for C E L.


MGBV8
Carl Floyd
Kingsport, TN
(4513 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Engine warning light from 94 GM 3.4 PCM
Posted by: MGBV8
Date: September 02, 2015 09:42AM

Generally, you use a resistor with a LED.

[led.linear1.org]
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kstevusa
kelly stevenson
Southern Middle Tennessee
(985 posts)

Registered:
10/25/2007 09:37AM

Main British Car:
2003 Jaguar XK8 Coupe 4.2L DOHC/ VVT / 6sp. AT

authors avatar
Re: Engine warning light from 94 GM 3.4 PCM
Posted by: kstevusa
Date: September 02, 2015 10:53AM

I just ordered an Orange 12V. led from Speedway motors assortment and connected directly to the feed from my ECM. Nary a problem, it has illuminated; so it works. No parallel series so is resistor needed?


danmas
Dan Masters
Alcoa, Tennessee
(578 posts)

Registered:
10/28/2007 12:11AM

Main British Car:
1974 MGBGT Ford 302

authors avatar
Re: Engine warning light from 94 GM 3.4 PCM
Posted by: danmas
Date: September 02, 2015 12:34PM

Quote:
Generally, you use a resistor with a LED.

When you buy an LED labeled for 12 volts, such as these, it will have a resistor built in.
image.jpg
image.jpg


MGBV8
Carl Floyd
Kingsport, TN
(4513 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Engine warning light from 94 GM 3.4 PCM
Posted by: MGBV8
Date: September 02, 2015 01:41PM

Right, Dan. I was thinking of a bare bones LED.

http://cdn-reichelt.de/bilder/web/xxl_ws/A500/LED3ST.png

Kelly, in series in a basic LED application to limit the current (& adjust the brightness).


danmas
Dan Masters
Alcoa, Tennessee
(578 posts)

Registered:
10/28/2007 12:11AM

Main British Car:
1974 MGBGT Ford 302

authors avatar
Re: Engine warning light from 94 GM 3.4 PCM
Posted by: danmas
Date: September 02, 2015 02:59PM

Quote:
... in series in a basic LED application to limit the current (& adjust the brightness)

Carl,

I used the LEDs shown in the top pic in my MG. The blue LED high beam indicator was blindingly bright compared to the others, so I had to add a resistor in series to tone it down a bit.



kstevusa
kelly stevenson
Southern Middle Tennessee
(985 posts)

Registered:
10/25/2007 09:37AM

Main British Car:
2003 Jaguar XK8 Coupe 4.2L DOHC/ VVT / 6sp. AT

authors avatar
Re: Engine warning light from 94 GM 3.4 PCM
Posted by: kstevusa
Date: September 02, 2015 03:03PM

OR, just purchase from Speedway, solder and shrink wrap & mount. No reason to complicate things :-)


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