12 Volt Basics/Safety
Printed From: the12volt.com
Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=1857
Printed Date: July 24, 2025 at 10:31 AM
Topic: 12 Volt Basics/Safety
Posted By: frstwlkr
Subject: 12 Volt Basics/Safety
Date Posted: July 10, 2002 at 11:55 PM
I'm a novice installer diving into car electronics. I've ordered a Fluke model 77 DMM, and have basic tools. I've been told that some rigs may set off the air bags when a wires is tapped into, some say to always disconnect car's battery before touching any wires, otheres say it's not necessary. Please give Your advice on general dos and don'ts, wires to stay away from, customary grounds, hots, running wires from fuse box vs tapping into existing wires, etc. COOL SITE. Thanks!
Replies:
Posted By: GlassWolf
Date Posted: July 11, 2002 at 5:12 PM
with alarm system wiring, fog lamp wiring etc, yes always disconnect the battery. This will help avoid discharging the airbag accidentally.
Airbags are also backed up by a capacitor, so give that a minute or two to discharge fully as well.
Most cars have a fuse or switch to disable airbags as well if needed.
For putting in a radio, generally I don't bother as that's simply plugging in a wiring harness, and comes nowhere close to the airbag wiring.
a DMM won't trigger an airbag like a test lamp will. a test lamp draws current to light the bulb, and thus can trigger the deployment, whereas a DMM represents usually something around 20mega-ohms of resistance to simulate an open circuit. This is sufficient to prevent anything in a 12VDC system from detecting it's presence in a circuit.
Mostly use common sense and stay on the safe side if unsure.
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-GlassWolf
Pioneer Stage-4, Orion, DynAudio, Fi
Posted By: Ronaldo
Date Posted: July 11, 2002 at 6:05 PM
If you disconnect the battery, how are you supposed to verify that you are connecting your accessories to the right wires?
Posted By: mobiletoys2002
Date Posted: July 11, 2002 at 6:38 PM
well frstwlkr i f you stay away from the yellow loom as well as the orange looms these are the colors of the loom they put over airbag harness wiring. Also some air bags will dispaly a light on your dash after removing battery, so if this happens to you then that requires a trip to the dealer to get the code erased. This is why it is usually recomended not to disconect the battery . As far as being on the safe side- always when working around the dash you will not want your face in front of the steering wheel in case something goes wrong. But if you have a general idea of where to connect your wires the chance of this happening is slim. And to verify the corect wires on an alarm you will need power to check the wires. You cannot just go by diagrams because 50% of the time they are not that accurate. You also want to be carefull around the ignition not to short wires out if your cutters touch the ignition or any piece of metal you will short something out . Its pretty much common sense when you are working on wires verify all connections with a (dmm) not a test light as damage to the vehicle can occur. Another good idea is to keep the windows rolled down and the domelight bulb pulled out this will make sure you dont drain the battery or get locked out of the car. 
Posted By: GlassWolf
Date Posted: July 12, 2002 at 9:55 AM
The answer to your question is this:
Know your wiring color codes before you go hacking into the dash of a car!
Get the wire code CD ROM from some place like Metra, Excalibur, etc.. and USE it.
Also use proper wiring harnesses. No reason to cut them out of a car when you can just plug stuff in properly the first time.
pulling the dome light is a nice idea, but not always practical since in vehicles like my Jeep, it has no less than 4 dome lights. 2 in the ceiling and two under dash you'd need to actually unscrew plates to remove. It gets worse when the car has lights in the door panels etc too.
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-GlassWolf
Pioneer Stage-4, Orion, DynAudio, Fi
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