Head unit won't turn on

[Rambo819]

I installed a capacitor and dynamat last night and hooked my amps and sub back up today. I had all the wires labeled so everything is hooked up correctly. I went to test it out this morning and now my head unit won't turn on, I checked all the fuses and even hooked up my old headunit and nothing still. Are there only 2 fuse boxes (one under the hood and one on the side of the dash)? I did try to wire an led into the trunk light and after i hooked everything back up last night the trunk light didn't work but I don't think that would have anything to do with the head unit not turning on. Any help, I am lost???

Thanks in advance

[quicksilver22]

Did you reconnect your battery...?

[Rambo819]

yea, i did the red and black wires have 12 volts when the key is on, i test it with my voltmeter. I am unsure why I am not getting a reading on the yellow wire, its suppose to be 12+ battery.

[pinoyesv6]

are you sure you checked all the fuses? preferably with a test meter to make the fuse is actually still good?

[Jeffylou87]

You blew a fuse when you installed everything..

[mitgalantes]

you sure your lookin at your fuses cuz you can tell if a fuse is blown....you sure you hooked up the cap right did you remember to ground the cap and the cap also has to be hookup to the battery..

[Fishboy55]

I will almost guarantee you that one of the fuses in the yellow protector under the hood is blown. Have you tried disconnecting everything, restoring it to the way it was before you started and powering on the HU? If you do that and the HU doesn't turn on, you have a blown fuse for sure.

[Rambo819]

I ran a wire straight from the battery to the yellow wire on the HU and everything worked. I also noticed when I did that the beeping, when the door is open and the key is in the ignition, wasn't working and the hazard lights wouldn't turn on unless the car was on.

I switched out the 2 fuses I could find for the HU one 10 amp and on 20 amp.


Whats this yellow fuse box? I only saw a black one by the driver's side front strut and one on the driver's side of the dash. Is there another one? Is there a fuse for the trunk light since it hasn't been working either? I couldn't find one.

The cap is hooked up correctly because it has a relay that stops it from turning on if its incorrectly hooked up. Pos from battery to cap, pos from cap to amp, neg to cap and neg from cap to amp.


Its has to be a fuse but I checked pretty much every fuse and can't find a bad one. Any other ideas.

Thanks for all the input, I appreciated it because I am lost on what this is.

[SkylineG1]

you blew a different fuse than what you are looking at. Check all your fuses under the hood & the one's inside.

[pinoyesv6]

I ran a wire straight from the battery to the yellow wire on the HU and everything worked. I also noticed when I did that the beeping, when the door is open and the key is in the ignition, wasn't working and the hazard lights wouldn't turn on unless the car was on.

you just contradicted yourself. what works and what doesn't?

Whats this yellow fuse box? I only saw a black one by the driver's side front strut and one on the driver's side of the dash.

open up the engine bay fuse box and you'll see fuses in a yellow holder. typically that would point to your answer.

[Jeffylou87]

Don't do your audio..

[mitgalantes]

I HOPE YOU CHARGED YOUR CAP FIRST BEFORE INSTALLIN IT>>>power cable goes from battery to cap + terminal. separate power cable from cap + terminal to the amp. make sure the amp and cap are grounded.

[Rambo819]

you just contradicted yourself. what works and what doesn't?

I didn't realize the the hazards and the beeping wasn't working until i hooked up a new wire straight from the battery.

open up the engine bay fuse box and you'll see fuses in a yellow holder. typically that would point to your answer.

The way I read that post before made it seem there was a separate yellow fuse box not a yellow holder inside of the fuse box. I will go check those fuses here in a little bit.

I HOPE YOU CHARGED YOUR CAP FIRST BEFORE INSTALLIN IT>>>power cable goes from battery to cap + terminal. separate power cable from cap + terminal to the amp. make sure the amp and cap are grounded.

Yes the CAP is charged. I am 99% sure it is hooked up right because the internal relay would display and error on the digital display if it wasn't hooked up right and everything is on the CAP is doing its job. I will try removing the CAP and put everything the way it was and see what happens

And why in the heck did you give the HU a 12v source straight from the battery? You have a 12v source in your wiring harness. I think you blew more than 1 fuse and or fried the HU

The 12v source wasn't working when I ran a new 12v wire from the batt and replaced the source wire everything worked hazards, beeping and the HU. It has to be a fuse, just can't find it.

I have never had a problem doing my own audio before and have installed 4 different systems. This one has me lost but I am going check the rest of those fuses and let you guys now what I find.

Thanks for the help

[Rambo819]

I found the problem it was the 10 amp dome light fuse....now I can rest easy finally.

Thanks for all the input!

[Fishboy55]

I will almost guarantee you that one of the fuses in the yellow protector under the hood is blown. Have you tried disconnecting everything, restoring it to the way it was before you started and powering on the HU? If you do that and the HU doesn't turn on, you have a blown fuse for sure.

I should have bet money... 8 Years on TGC and it's always the same thing....

I found the problem it was the 10 amp dome light fuse....now I can rest easy finally.

Thanks for all the input!

Someone should keep track of how many times someone installs their own audio, blows the fuse and then tries everything EXCEPT replacing the fuse to fix it.

Glad you fixed it. This is why anyone who knows anything about audio disconnects the battery before installing any components.

[pinoyesv6]

Chip, let me fix that statement for you...

Someone should keep track of how many times someone installs their own audio, blows the fuse and then tries everything including checking all the fuses EXCEPT the fuse to fix it.

but yea, when working with you car's electronics, whether it be you lighting or your audio or what not, you should disconnect the battery. just reconnect it if you need to do tests or when you're done. besides blowing fuses, you reduce the risk of electrical fires and shocking yourself if you disconnect the battery.

[ZigenScarface]

don't you mean the "-" terminal to the amp?

i hope this is a joke.. if not dont do your own audio...

positive on cap gets wire in from bat and wire out to amp positive
negative on cap goes to chassis, so does negative on amp...

and if you have yours setup this way dissconnect it right away!

[Jeffylou87]

Ftl..

[Rambo819]

I had the battery disconnected but I put the cable on to test out my wiring and ended up changing a few things after and forgot to disconnect it again when I tried to wire up and LED bar to the trunk light and must have crossed the wires at some point. I am guessing that what caused it. I almost always disconnect the battery before doing any work to my car but it must have been losing my mind by that time in the night.

Thanks for the help, I wouldn't have thought the dome light fuse was in series with the HU fuse. Just glad I figured it out.

[ZigenScarface]

if u had a cap ud love it ;) and im MECP certified.. i know how to install a cap =p