I have a 1/0 awg dedicated line running to a distribution block in my trunk. Now this morning I go to drive my car & the amplifier won't turn on. The car starts up fine, the head-unit powers up, but nothing happens with the amp. Realizing I needed to get where I was going I held off looking more into it til this evening. So after going thru all the steps to see where the problem is (check voltage, check relays, check fuses, etc) things gets weird...

With the car ignition off the distribution block voltage is fine (12.8 volt avg), but as soon as I engage the accessory setting the voltage on that line drops to 300mv. This also stays the same when the engine is running as well.

The 1/0 awg line is not new (installed about 3 months ago) and has been working fine up until this morning. Does anyone have any ideas as to what else I should be looking for?

 

Potential short, although I would expect a fuse to pop. Is the line fused at the battery?

 

Did you try connecting the remote wire terminal to a hot 12 volt wire and see if that's working?..

It might be just something as simple as the remote wire coming lose or was fried.

 

When tracing back the issue, I found that it seems to be with the 1/0 awg line itself by testing the voltage on the distribution block in the trunk with no output wires connected. This is a straight run to the battery with a fuse just off the post.

I looked at the fuse and it doesn't look popped. If it was a short, wouldn't the voltage be the same even with the ignition off? The drop only occurs when the ignition is engaged, and only appears to affect that line.

 

That sounds really odd...

 

Tell me about it, it started happening out of the blue.

 

Check your voltage on both sides of the fuse, with ign on and off.

Put your DMM on continuity or ohm and check the fuse - may not look blown but can still be bad.

I have seen some amps feedback 12VDC on the supply side when they are off (internal caps?) - even when the supply line is disconnected. When you turn the ign on is the HU also on?

Try the ign on-off test with the HU both off and on.

 

I'll check the voltage on both sides tonight when I get home.

The HU powers fine, it's on a separate line (Here is a quick shot of my battery). The 10 awg for the HU shares the post with the 4 awg line to the fusebox. The 4 awg line to the alternator is by itself. The yellow 1/0 awg is the line with the problems right now.

 

I would start with at the battery and work your way back testing it out. Like Will said that power your seeing could be from the HU remote sending power through it or the internal caps...

Check that fuse with the MM and then move on. This has got to be something stupid... its just to wierd.

 

It's looking like its a short in the remote signal wire. Once I disconnected that from the back of the HU, the voltage stays stable. Unfortunately it looks like it fuxor'd my amp in the process & now I have to wait on a replacement from cardomain (good thing for replacement warranties).