BritishV8 Forum

General Category => Engine, Transmission, & Rear Axle assy. => Topic started by: limey222 on September 01, 2015, 07:04:38 PM

Title: Engine warning light from 94 GM 3.4 PCM
Post by: limey222 on September 01, 2015, 07:04:38 PM
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: http://www.ebay.com/itm/321705079086?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Title: Engine warning light from 94 GM 3.4 PCM
Post by: limey222 on September 02, 2015, 01:34:38 AM
 -- moved topic --
Title: Re: Engine warning light from 94 GM 3.4 PCM
Post by: kstevusa on September 02, 2015, 08:01:55 AM
Should be OK, I used a orange LED for C E L.
Title: Re: Engine warning light from 94 GM 3.4 PCM
Post by: MGBV8 on September 02, 2015, 09:42:51 AM
Generally, you use a resistor with a LED.

http://led.linear1.org/1led.wiz
Title: Re: Engine warning light from 94 GM 3.4 PCM
Post by: kstevusa on September 02, 2015, 10:53:20 AM
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?
Title: Re: Engine warning light from 94 GM 3.4 PCM
Post by: danmas on September 02, 2015, 12:34:28 PM
QuoteGenerally, 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
Title: Re: Engine warning light from 94 GM 3.4 PCM
Post by: MGBV8 on September 02, 2015, 01:41:55 PM
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).
Title: Re: Engine warning light from 94 GM 3.4 PCM
Post by: danmas on September 02, 2015, 02:59:59 PM
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.
Title: Re: Engine warning light from 94 GM 3.4 PCM
Post by: kstevusa on September 02, 2015, 03:03:52 PM
OR, just purchase from Speedway, solder and shrink wrap & mount.  No reason to complicate things  :-)