A couple weeks ago I installed my new amp (Aura RPM-4200) and speakers into my truck. It's a 2000 F-150 Lariat, and I am using the stock HU.

I started off using the speaker level inputs on the amp, as my stock HU has no pre-outs, and I figured I may as well use the speaker level inputs since I am already running new speaker cable's. So I got everything installed, and find that I have almost no right channel. If I hook up a speaker to the right channel (either front or rear right channel) music does come from the speaker, but it's so quiet you have to crank the HU volume up to full to really hear anything, and it's very crackly.

So I checked everything, switched speakers/crossovers/cables from left to right etc and still had almost nothing coming out of the right channel. I removed and reinstalled the speaker level input (used different cables to make sure I had not got the inputs/outputs messed up, ruled this out as with them round the wrong way I get 0 sound at all). I checked grounds, gains, balance etc............. still nothing. At this point I start to think maybe my amp is bad.

I then find a suggestion about using an MP3 player and a 3.5mm to RCA cable to test out the amp. So I go buy one of these cables, plug it in and sure enough, I get both left and right channels. So that then rules out my amp.

I go back again and re-check all my input cables and again cut and re-crimp each one making sure I get everything correct. STILL NOTHING!! So I give up and go out and buy a Line Out Converter (and some RCA Y-cables). I get home and give the MP3 player another test using the RCA Y-cables, and get music from all 4 speakers.

Next I went ahead to install the LOC, since I already had speaker cable running to the amp (from the speaker level inputs) I decided to use these for my LOC (if I got interferance using these cables I had planned to relocate the LOC to the back of the HU). I hooked up the LOC to the rear speaker cables, grounded it and had everything connected with no problems. Switched on the HU (first thing I notice is how much better the sound is with an LOC instead of speaker level inputs) and the 2nd thing I notice is STILL NO RIGHT CHANNEL!!!!!!!!!!!!!!!

So I begin to think maybe it is a problem with my rear speakers (the wire colors I have are different to 99% of diagrams I found on the internet) but they work when using the MP3 player, so I am sure I have the right cables. However, to eliminate this variable I decide to hook the LOC up to the front speaker cables, STILL NO RIGHT CHANNEL. If I switch the left and right RCA's the sound moves from left to right, but no matter which way I wire it I STILL GET NO RIGHT CHANNEL.

So I know my speakers all work, I know all channels on my amp worked, I am 99.99% sure that the balance all worked on my HU before starting this, I know it's not my RCA cable as I get the same problem using speaker level inputs.

And so here I am on Wednesday morning with still only half my speakers working, and fast running out of idea's as to what I can check. The 1 single thing I just now thought of is that maybe my + and - are wrong coming into the LOC on the right side, but I find it hard to believe (although still possible) that I managed to get both front and rear on the right side mixed up on the input (LOC/Speaker level) side of things, but that the output (going to speaker from amp) would be correct. The other thing I might check is to remove the amp from the loop and hook the speakers up directly to the HU and just be certain that I have all 4 working running off the HU. Other than those things I am really really stuck.

I heard that some Ford's come with a factory amplifier, could this be causing the problem I have? As far as I was aware I don't have the factory amp, and it's weird that it would cause only the right channel to not work. I don't have anything on my speakers/HU that indicates its a premium system (and the speakers I removed look far from premium!!) but it is the tape deck with the 6 disc changer. Is there any way I can check for the factory amp?

The thing that sucks is I don't know when I can next get time to even look at this, my wife is getting pretty p*ssed with me spending several hours at the weekends on what I told her should not really take more than a couple of hours. So the earliest I can even look at it now is going to be this weekend, and I am not yet sure if I can even do that.

Really fed up with this though, I have no idea what else I can check. Is it possible I fried something on the HU when I first installed? Nothing weird happened when I first powered it on (other than half the speakers not working properly). So I am doubtful (and hopeful) that nothing is wrong with the HU itself.

So any help is massively appreciated, I am completely stuck. Fully p*ssed off, and have no idea what else to try. Thanks for reading, sorry for the long post, trying to provide as much info as possible.

 

I tried following all that the best I could...
Disregard if you tried this already....


From the HU location.... make yourself a set of test leads and jumper from a known set of Working speaker wires from the back of the radio to the "non-working" set. You may have find a few paper clips or something similar to shove lighty into the Back-side of the harness (where the wire comes in) and individually wrap the wires around the paper-clip. Electrical tape if necessary! And make sure they Do not Touch!....

 

Thanks for the reply, what you suggest is about the only thing I have not yet tried. If I get time this weekend I plan to disconnect the amp and hook the right side speakers up directly to the HU again. If the speakers work connected directly to the HU then I have a wiring problem (what I am hoping) and if they don't work then it looks like my HU has a problem (if it does have a problem I have no idea what I did to create it).