Blowing fuses!

Well, I have a Pioneer DEH-1500 that I am trying to install in a '93 Mazda B2200. Everything was great until I realized that the wiring harness that cam with the stereo did not have the inline fuse attached for the 12V constant. So, I just reused the inline fuse that was attached to the previous stereo in the truck. When I power up the stereo it starts for a minute until I try to insert a CD when the stereo dies and blows the 32V .5A inline fuse that is attached to the 12V constant wire. My question is this, what are the fuse ratings for this stereo and vehicle for the 12V constant and the switched inline fuse? Or is there a universal rating that is obviously greater than .5A? I really need your expert help, I know I am a newbie but I just want some music while commuting. Can you help a guy out? Thanks.

More than likely it is a 10 amp fuse. You may be able to find that info out at pioneer's web page.

That is the thing, I have been to the Pioneer site and spent alot of time looking there as well as other web sites. You can understand that I do not want to damage my new radio due to my lack of experience with these things. Hopefully, someone can help me out here. I have been singing to myself and getting some crazy looks on the road.

Most manufacturers use 10A for their fuses. Even car manufacturers generally wire in a 10A fuse for the HUs.Sam Roza

It is just the constant that I am having problems with at the moment as I have blown several .5A inline fuses. I would have expected the Pioneer site to be more helpful, perhaps I need to try a 2A and increase until the fuse stops blowing. That seems somewhat logical until I can get a definitive answer. I know this seems very rookie-like but I just want to rock out again in my little mazda.

If you refer to page 19 of the Pioneer DEH-1500 owner's manual it states the max current draw is 10 amps.  Use a 10 or 12 amp fuse.  This deck (and most decks) SHOULD immediately blow a 0.5a fuse.Support the12volt.com

in the "old" days the B/U lead was used primarily for maintaining memory for the clock and radio presets... that was this circuits sole function... nowadays, more often than not the B/U circuit provides VCC to the output stage which is powered all the time and simply goes into a "wait state" until it sees ACC power again... this means that the B/U circuit is now the power supply for the entire radio and as such requires far more current handling.... 10-15 amps  vs. the 100-500 ma it used to require.....Kevin Gerry

Certified Electronics Technician

MECP First Class Installer

Owner/Installer

Classic Car Audio

since 1979

Well, I think I have bigger problems now. I installed the 5A fuse for the constant and listened to a CD for about a half hour when it began to screech. I immediately shut it off and disconnected the wiring harness. After inspecting the fuses and wiring which appear to be correct I powered the unit back up. Now when I increase the volume past level 0 the unit screeches and the power cycles about every 2-3 seconds. I don't get any music out of the speakers and when I disconnect the speakers the unit is still screeching although much quieter. If I didn't know any better I would say that a capacitor is discharging. What is up with this unit??!!! HELP!!

Disconnect your ground from your factory wire harness and find a nice chunk of metal behind the dash , put your wire in a o-ring crimp on connector and secure it to the metal with a already existing bolt.  But be shure to give the metal a quick sand with some sand paper.  Hopefully that should be your only problem.2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.