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MIL light wiring issue

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Old Jan 17, 2013 | 06:33 PM
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Default MIL light wiring issue

well, I decided to pick up a check engine light for the dash, so i drilled a 5/16" hole connected the brown wire from comp. harness (psi harness) to light, then another to 12v. my problem is when I start engine the light comes on for 2-3 seconds and goes out, burning the bulb, tried it twice, same results. (red light with short pigtail from oreillys). thoughts???? before I installed in the dash I tested the light under the hood across the battery for 30 seconds or more????
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Old Jan 17, 2013 | 06:57 PM
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It should come on for a few seconds, that's normal. Burning out the bulb seems odd. I'm assuming you removed the bulb and tested it on the battery?
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Old Jan 17, 2013 | 09:15 PM
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When you say you tried it twice, do you mean you turned the key on twice or tried two different light bulbs? I agree, it's odd that it would actually burn the bulb out if you first tried it on a battery and it didn't.
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Old Jan 18, 2013 | 06:54 AM
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The brown wire from our harness (underdash section) should be going to the bulb and then the other side of the bulb goes to switched 12-volt power. Are you using a 12-volt bulb, led or something else? Give us a call if you would like to discuss.

Jon
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Old Jan 18, 2013 | 04:35 PM
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Yes Jon,did like you said with 12v bulb. I'll call you when I get a chance.
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Old Jan 18, 2013 | 05:06 PM
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I have something related to this. I picked up an led light to use as my CEL and after the truck starts, the light will dim but never goes completely out. Have you guys heard of this? Should I add a resister or something to the circuit? Is there a reason the led stays lit after it starts? After reading this thread I thought I would ask. Thanks, Jason.
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Old Jan 18, 2013 | 05:12 PM
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Your LED operation is normal.
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Old Jan 19, 2013 | 07:52 AM
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Oh, okay. But if I did want it to go out completely, how would I go about that? Increase the resistance if the circuit?
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Old Jan 19, 2013 | 08:55 AM
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Nope. Use a LM7805 voltage regulator between the 12 volt supply and the led. That will not let it illuminate till the PCM drives the cel to ground.

Read my post comment here
for background info as to why it is dimly lit.

https://ls1tech.com/forums/conversio...s-present.html


I still prefer to have a dimly lit LED as a check that it is functional. It will be fully BRIGHTLY lit when you first turn the key on then go dim after the car starts running as long as you dont have any codes.

Last edited by aknovaman; Jan 19, 2013 at 07:04 PM.
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Old Jan 19, 2013 | 12:42 PM
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Thank you very much for posting that.
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Old Jan 19, 2013 | 05:56 PM
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Ok, new info here! Before posting my problem I should have checked the second bulb, turns out mil light is working correctly. I took it for a drive today and light came on and stayed on the whole time, plugged in tool and malfunction on bank one, maybe o2 sensor? Confused me because I thought the mil light would come on every time you start the engine, but only briefly and go out?
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Old Jan 19, 2013 | 08:14 PM
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It should pop on for a few seconds as a check to show it isn't burned out, then go out until the PCM sets a code.
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