wcbjr Posted January 24, 2006 Share Posted January 24, 2006 So I was tapping the radio's 12V constant and ignition sources for the CleanSweep last night and forgot to unhook the + battery terminal. Just so happens that I touch the 12V constant (yellow wire) to the radio's chassis. Sparks flew, let me tell ya. But it didn't long. As soon as that stopped the interior lights all went out, even the trunk light. Alarm didn't work either, pertty much nothing. I tested and tested until I came to a fuse that I thought was a spare because it said "backup". What in the world is that fuse supposed to mean? Why didn't I blow the audio fuse? I forgot what I was supposed to remember. Link to comment Share on other sites More sharing options...
rony Posted January 24, 2006 Share Posted January 24, 2006 Are you sure that wasn't the lumination lead? My Car vBGarage Link to comment Share on other sites More sharing options...
wcbjr Posted January 24, 2006 Author Share Posted January 24, 2006 Oh yes, I know it was the yellow. I forgot what I was supposed to remember. Link to comment Share on other sites More sharing options...
NatesGr8 Posted January 24, 2006 Share Posted January 24, 2006 you should always disconnect the negative lead. Link to comment Share on other sites More sharing options...
wcbjr Posted January 24, 2006 Author Share Posted January 24, 2006 Details, details, but you're correct. I forgot what I was supposed to remember. Link to comment Share on other sites More sharing options...
crash Posted January 24, 2006 Share Posted January 24, 2006 I blew the backup fuse this weekend... I was doing the map light mod and I touched the + and - terminals together when I was swapping their positions in the connector. Anyone know what the "backup" 20A fuse is? Link to comment Share on other sites More sharing options...
emosound Posted January 25, 2006 Share Posted January 25, 2006 Methinks "backup" = reverse lights. -Paul Link to comment Share on other sites More sharing options...
mikeyd Posted January 25, 2006 Share Posted January 25, 2006 In my experience, the "backup" many times is labled as such because it maintains constant power to things such as the radio which need to keep settings or have "backup" power when its switch power source turns off. I have also seen cases where it stands for the reverse lights, but it sounds like in this case it was obviously the constant feed to the radio and also the BIU (contains the alarm/keyless). I've been doin the whole automotive electronics for years and consider myself a professional in that sense, I almost never unhook the battery but instead only be carefull when I'm working with any wire. Every stock wire which is hot runs into a fuse at some point and that is more or less the reason fuses exist after all. The only time u should really worry is when your working on wires going into a module of some sort as you could short something to power or ground that could damage a component inside the module. Good times. Add one-touch operation (and more) to your stock sunroof Link to comment Share on other sites More sharing options...
emosound Posted January 25, 2006 Share Posted January 25, 2006 Could be that, too. The only thing labeled backup in the electical diagram is FB-35 which powers the backup relay (AT), backup switch (MT), Inhibitor switch (AT), and the DRL control module. -Paul Link to comment Share on other sites More sharing options...
Th3Franz Posted January 25, 2006 Share Posted January 25, 2006 Ah, it's only 12V. -Franz The end of a Legacy http://www.youtube.com/th3franz Link to comment Share on other sites More sharing options...
mikeyd Posted January 25, 2006 Share Posted January 25, 2006 Ah, it's only 12V. Yeh , hasn't killed me yet Add one-touch operation (and more) to your stock sunroof Link to comment Share on other sites More sharing options...
wcbjr Posted January 25, 2006 Author Share Posted January 25, 2006 In my experience, the "backup" many times is labled as such because it maintains constant power to things such as the radio which need to keep settings or have "backup" power when its switch power source turns off. I have also seen cases where it stands for the reverse lights, but it sounds like in this case it was obviously the constant feed to the radio and also the BIU (contains the alarm/keyless). That would make sense seeing as how the interior lights went out along with the trunk light, all of which are usable when the key is not in the ignition. I forgot what I was supposed to remember. Link to comment Share on other sites More sharing options...
hal9e3 Posted August 20, 2013 Share Posted August 20, 2013 I was replacing the combo intake/exhaust manifold gasket on my 1972 Volvo 142 (POS doesn't even BEGIN to describe it) when I dropped a socket wrench and it lodged between the + terminal on the alternator and the chassis. Unfortunately the wire was part of the harness that ran along the top of the radiator. Harness caught on fire, battery caught on fire, I finally chopped the + cable in two with something, can't remember what. $400, which was a lot of money in the 70's, to fix it. I STILL don't disconnect the + terminal because I figure I've had my Black Swan event for one lifetime:) Link to comment Share on other sites More sharing options...
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