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Auto Electronics/Indicator bulb smoked

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Question
Problem: indicator bulb blew so replaced with 12v 21watt as per usual, but when turned on to test, it smoked inside and the glass went for clear to white in about 3  or so seconds. Basically fried itself. battery read 12.74v and the contacts are clean. dud new bulb ?   maybe ??  any idaes thanks

Answer
Hello James,

This is a question i get asked very frequently, i recommend reading the answers i have given on light in the past, however, for the current moment:

This sounds to be a situation where you have one of three things going on.

1. Bad Ground wire
2. Short in the wire
3. Ground out

To start, if the vehicle has a bulb system where the bulb is dual filament meaning it handles say brake light and turn signal light, then you are dealing with a 3 wire bulb setup.

To check for a problem you will need a test light.  Ground the test light  and then probe the tip into the wires on the lights harness.  One wire will make the bulb in the test light come on when the brake is pushed, the test light bulb should remain on as long as the brake is being pressed.

The next wire should turn on when the signal is turned on and the bulb in the test light will flash in time with the light.

The third wire should not make the test light turn on at all, this is your ground wire.

If the bulb to the test light blows, you know that that wire is where your problem is.  Trace the wire and check for broken, frayed or grounded wires.  If the bulb wont light at all, ensure it is not the ground wire, by testing the other wires, normally the ground wire is a solid color wire, however they can be multicolored.  If the bulb is not lighting on a wire that it should be, then you know that that wire is part of your problem.  Check that for broken, frayed, or grounded wiring, and also check all fuses controlling the light.

For additional information refer to my earlier post at this link on all experts.

http://en.allexperts.com/q/Auto-Electronics-3977/2010/11/Tail-Lights.htm

Please keep me informed of your progress.

Thank you and Good Luck.

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Antonio Ibarra Jr.

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I am here to answer any questions regarding Automotive Electrical. Specifically automotive aftermarket products and their application, installation, diagnosis and repair. I am also able to assist with ANY and ALL qeustions relating to EMERGENCY VEHICLES, to include POLICE, FIRE and EMS Vehicles, their components, order options, equipment, maintenance, upfitting of aftermarket equipment and more.

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I have 10 Years of automotive & aftermarket industry experience, both working as a technician and now running my own business, selling, servicing, repairing and installing automotive aftermarket equipment into personal vehicles as well as emergency vehicles. I am a licensed Master Automotive Electrical Technician (ASE Certified), I am also Certified by the Emergency Vehicle Technician Certification Commission as an Emergency Vehicle Master Technician. I am Certified by Motorola as a Master two-way radio repair technician for low band, high band, VHF, UHF, HAM radios and CB radios. I am a Certified Master Emergency Vehicle equipment and component service and repair technician. I am a Certified Master computer components and interfacing/networking service and repair technician. Licensed Master fabrication specialist. Whelen accredited and certified Master Emergency Vehicle Systems Repair Technician

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ASE Certified, EVTCC Certified, EVOCC Certified, CEVO II Police, Fire and EMS Certified, DOT certified, NTSB Certified, FEMA Certified, NYS DMV Certified automotive Inspector and Master Emergency Vehicle Inspector. I am the owner of one of THREE businesses in the Tri-state area licensed by the DOT and NYS DMV to certify Emergency Vehicles for street use. I am Motorola Certified, Whelen Certified, Dell Certified, Panasonic, Gateway, and Mobile Computing Systems Certified, Kenwood Certified and Yeasau Certified. I have 10 Years Industry Specific Experience. I also Run my own business in the automotive aftermarket industry.

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