radio installation antenna causes short

-
pishta

pishta

I know I'm right....
Joined
Oct 13, 2004
Messages
23,821
Reaction score
13,679
Location
Tustin, CA
Here is a strange one. I installed a stereo head into my mazda (sorry but it may have general interest too) and it works fine until I plug in the antenna lead. then it blows my 10A dash/taillight fuse! This is very strange. I ohmed out the antenna, it has no short between the center conductor and the ground sheathing, its only tightened to my fender, not an active antenna. I probed the antenna socket on the radio, the socket is grounded with the chassis and there is only .11v on the center contact. There is no continuity between the antenna socket and the center conductor. It works fine with the unit on AUX (no antenna installed) but as soon as I connect antenna, it blows fuse?? It has its own 15A fuse but it runs through a 10A circuit. Should I up the 10A to 15A or just run a dedicated power lead to battery? I liked the harness connection becasue the radio would turn off with key. Oh, and this radio (Boss 612UA) has dismal PLL signal lock, it will drift (treble comes and goes like the speakers are going underwater) while sitting at a light as well as on the road but only when using radio (with no dash or taillights...)
 
pishta said:
Well, I googled it and found this: http://forum.miata.net/vb/archive/index.php/t-53862.html

I guess my ground may not be a constant ground after all? This guys harness ground turned into a 12V+ when the lights turned on.....Hmm, you think you checked everything....
Click to expand...

That was my first thought.
Antenna connections don't carry any voltage that could blow a 10 fuse.

The other question would be WTF?! :D
 
WTF is right, I didnt check whether my "ground" was actually a ground when the dash lights were ON! Turns out it was the 12V+ dash light feed to the old radio, so as soon as I "hit the lights" fuse goes sizzle.......[ame]http://youtu.be/863fYC-Mb_Q[/ame]

All good now. will test reception tomorrow, couldnt get any worse.
 
Damn!! Well I guess you are lucky that this being a pretty complicated solid state device, you didn't smoke it somehow
 
I had a similar problem Friday evening. I was driving my kit car home and turned on the instrument lights, the engine lost power. It was not completely dark so I turned the switch off and all was well. I slept on the problem, because I could not think how that that could happen.

There is a secondary relay in the front since the tank and pump are up front, ECU and engine is in rear. The relay ground was tied to a spare instrument feed. I got the supply instead of the ground. The bulbs provided a good ground for relay coil, but with lights on relay turned off fuel pump. It is fixed now by using correct ground. I hope that is the only error. The wires are the same color, and the 33 year old number tags are falling off. I also have to get into a very awkward position to get under the dash.
 
Did you hear about the two antenna that got married?

The ceremony was boring, but the reception was great!!!
 
KitCarlson said:
.... I got the supply instead of the ground. ... It is fixed now by using correct ground. I hope that is the only error. The wires are the same color, and the 33 year old number tags are falling off. I also have to get into a very awkward position to get under the dash.
Click to expand...

I was flying blind too. I got the 82 Mazda Shop manual (all 120 pages!) and NOWHERE is there a wiring diagram...WTH? My ground is now a ground with everything turned on and engine running, even honked the horn.
 
I had n 81 Mazda, in my early days. Those fuse blocks,on the fender usually gather corrosion, and fail.. Just personal experience, Pishta.
 
already done it.....thanks! This is my second after an 18 year break.
 
You must log in or register to reply here.
-

Back
Top