Here's a riddle for you guys.

[SentraGuy 0]

Let's see if you can figure this out, because I sure can't.

Sorry about how long it is, I wanted to make sure I was thorough.

Here's some background:

-I drive a 2006 Nissan Sentra.

-I have a Fi BL 12 powered by a SAE 1200d in the trunk. Sounds awesome...

----My car has the "premium" sound system installed from stock . This means that a small Rockford Fosgate amp in the trunk is powering the front speakers. It also means that the signal for everything but the sub is being double-amped. You would never know though, the highs are clear as they were before. (More on this later)

On to the real problem..

I bought a Kenwood Excelon KDC-X794 to replace my stock head unit about 6 months ago. It looks and works just fine (When it does work).

But about 3 months after I bought it, I kept blowing a small 10 amp fuse (Fuse #1, it says "ACC, Mirror" next to it) in the fuse box under the steering column, EVEN at LOW volume, and sometimes with no bass hitting .

I called Crutchfield tech support (Awesome people, btw) and he first told me that I had not grounded the headunit right, because the stock harness in the car is not grounded, as this is what I used for a ground, and the headunit was trying to use the antenna for a ground as back up, and this is what was blowing the fuse. (Can you say run-on?)

So I regrounded to a bolt behind the head unit, and then powered up the head unit with the antenna UNPLUGGED, so this must mean the ground is fine.

Well, the fuse kept blowing. I called Crutchfield back, and talked to the same guy. He was baffled as well and told me to send the HU back, as it could be defective. And so I did. And they sent me another free of any charge.

I installed the 'new' one, and couldn't have been happier. The fuse was not blowing, even at full tilt. This lasted a while.

BUT, oddly enough, about 3 months after I installed that one (today), the same fuse blew again, at low volume.

Here is what I think it MAY be:

- Something to do with the signal being double-amped. Although I just have the small stock speakers up front.

-Two of the times it blew, I was playing the same song (Mi Casa, Tu Casa) but one time the volume was only at about 10/35. This song may have been playing some of the other times, I don't remember) COULD be a coincidence.

-Something wrong with how I wired the harness, although I repeated how I wired it to the Crutchfield guy, and he said I did it right.

-The guy from Crutchfield said that fuse (#1 under the steering column) should normally pull less that 1 amp, so something must be going drastically wrong for it to spike to over 10 amps at random.

If anyone can help me out at all, I will be very much appreciative . This is blowing my mind and I am running out of options.

[hove 15]

DAMN this is a tuff riddle!!! Good luck man! I really am coming up with a blank

someone will chime in here and hopfully get you what you need to know!

[Impious 1,476]

Is there a short in the power wire somewhere, or possible that the connection is making contact with something?

Can you make the event happen, or is it completely random?

Are you using the internal amplifier in the headunit?

[SentraGuy 0]

Is there a short in the power wire somewhere, or possible that the connection is making contact with something?

Can you make the event happen, or is it completely random?

Are you using the internal amplifier in the headunit?

Well, I did wrap all exposed wire with electrical tape or shrink wrap. Unlikely, but I will double check when I pull it back out.

I can not. I can replace the fuse RIGHT after it happens, and it may work for 10 min, then poof.

I am not, the dang stock amp in the trunk is still powering the front stage. I didnt even connect the speaker wires from the HU to the harness.

[SentraGuy 0]

Any other ideas?

[altoncustomtech 773]

The HU's internal amp isn't even hooked up to the harness? If so it's not being double amped, the stock amp is powering the speakers by itself.

[SentraGuy 0]

The HU's internal amp isn't even hooked up to the harness? If so it's not being double amped, the stock amp is powering the speakers by itself.

The RCA's are, and that is what is going back to the stock amp. I havent connected the speaker wires, is what I meant.

[altoncustomtech 773]

Right, so it's not being double amped, it's working the same way as it would with any external amplifier. Which also unfortunately rules out some problems I've seen where the HU's internal amp was driving the inputs of a stock amp, can cause problems like these. Have you measured the voltage behind the HU? I could see where constantly running on a low voltage could cause problems with the HU after a period of time. Or, perhaps the stock amp is on the same fuse and it's just starting to fail?

[Quentin Jarrell 671]

The factory amp under the rear deck has rca inputs? Are you sure you have a good ground and not grounding through the rca's?

[altoncustomtech 773]

They make harness adapters now to connect the aftermarket HU RCA's to the factory amp inputs.

[SentraGuy 0]

Right, so it's not being double amped, it's working the same way as it would with any external amplifier. Which also unfortunately rules out some problems I've seen where the HU's internal amp was driving the inputs of a stock amp, can cause problems like these. Have you measured the voltage behind the HU? I could see where constantly running on a low voltage could cause problems with the HU after a period of time. Or, perhaps the stock amp is on the same fuse and it's just starting to fail?

That's a good point about the voltage, ill have to check that as well. I have a stinger voltmeter, and my car stays at about a constant 14v. So I don't see why the voltage would be different behind the HU even at low voltage.

Ahhhh, I see what you mean about double amping. Thanks for clearing that up.

[SentraGuy 0]

The factory amp under the rear deck has rca inputs? Are you sure you have a good ground and not grounding through the rca's?

Well no, the stock RCA harness behind the HU runs into the amp, I was confused.

I checked the grounding point with a DMM, and it is definitely a good ground.

[SentraGuy 0]

They make harness adapters now to connect the aftermarket HU RCA's to the factory amp inputs.

Yes, I got the one that would work with the premium system.

[shizzzon 461]

unplug the rcas going out of the headunit into the STOCK amp.

This would leave just bass playing, correct?

If so, do this..

You say it only takes 10min for the fuse to blow again so try that...

If it works for more than 30 min.. the RCA grounding theory may hold true...

[SentraGuy 0]

unplug the rcas going out of the headunit into the STOCK amp.

This would leave just bass playing, correct?

If so, do this..

You say it only takes 10min for the fuse to blow again so try that...

If it works for more than 30 min.. the RCA grounding theory may hold true...

I will try that.

If this is the case, would that mean bad RCA cable? Or worse?

[shizzzon 461]

to ensure you test each theory out properly, I or we will let you know what to do next based on outcome.

[SentraGuy 0]

to ensure you test each theory out properly, I or we will let you know what to do next based on outcome.

I'm not sure if your reply cut off or what, but what should I test first?

[j-roadtatts 1,129]

unplug the rcas going out of the headunit into the STOCK amp.

This would leave just bass playing, correct?

If so, do this..

You say it only takes 10min for the fuse to blow again so try that...

If it works for more than 30 min.. the RCA grounding theory may hold true...

I will try that.

If this is the case, would that mean bad RCA cable? Or worse?

to ensure you test each theory out properly, I or we will let you know what to do next based on outcome.

I'm not sure if your reply cut off or what, but what should I test first?

[REVpuggie 23]

I suggest playing a test tone cd , testing if it happens on a particular frequency , this could mean there is a wire power wire making ground that is hanging in free air most of the time and makes ground when it resonates ...probably the wire got accidentally moved when installing the other HU .

please get rid of the electrical tape , there are kinds of tape what come loose in cold weather ...normally got something to do with how old the tape is and stiffness of the tape itself , the only good tape is the super soft one you have to pull untill it turns grey , that stuff will hold forever .

[Julian 641]

Hmm... Maybe the power wire is being pinched and grounding once you push it back in? I'd go over everything you did very slowly and carefully inspect for cuts/etc.

[SentraGuy 0]

Hmm... Maybe the power wire is being pinched and grounding once you push it back in? I'd go over everything you did very slowly and carefully inspect for cuts/etc.

I'm planning on spending most of today doing this, and testing out other various possibilities.

I'm also hopefully going to be buying some new speakers up front, and this will let me get rid of that stock amp in the trunk. Is it possible this amp is causing the fuse to pop?

[altoncustomtech 773]

That's a good point about the voltage, ill have to check that as well. I have a stinger voltmeter, and my car stays at about a constant 14v. So I don't see why the voltage would be different behind the HU even at low voltage.

Ahhhh, I see what you mean about double amping. Thanks for clearing that up.

It's just something to check. Factory wiring harnesses are well known for having a multitude of problems, low voltage not being a common one, but it's been seen.