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Factory Sub Amp Wiring

tdb420

Member
Joined
May 3, 2007
Messages
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City, State
Florissant MO
Year, Model & Trim Level
1993 Eddie Bauer 4x4
I am trying to hook up my factory sub woofer amp to an aftermarket head unit. To make it work I am using an RCA cable from the sub-out of the head unit that I am going to splice into the wiring harness that holds the remote wire and the positive and ground sound input connections. My question is how do I identify what the wires are so I can make the connection correctly.
 



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Don't attempt to splice the wires. The factory amp system uses a wacky shielded cable setup which is very difficult to splice. They sell adapters for a couple bucks that let you connect the radio to the connector without cutting it off.

Do you have the actual sub in the rear passenger side or just the cargo bin meaning you have the factory amp for the 4 speakers?

The factory amp is pretty bad, you'd probably be better off running the door speakers off of the headunit instead of the factory amp. My truck had the factory amp (no sub) and had an aftermarket radio installed with the adapter. I removed the factory amp and rewired the speakers. It sounds better that way than it did with the amp.
 






Alright I was able to identify the wires after I got my hands on a meter and I was able to make the splice. Now my problem is that the amp still doesn't work. My question is if the factory amp takes an RCA signal or if it takes essentially the signal from a headphone jack. If anyone has some insight on this please reply.
 






I have a 94 with JBL Sound.
The Factory amp does NOT take speaker level inputs from the radio. It takes only line level inputs. Also, it appears that the crossover frequency for the sub woofer is factory set, and takes place within the amp.(There may be adjustments on the amp but I haven't taken that panel off to get a look at the amp yet). The amp takes the 4 line level inputs and, of course, amplifies them and sends those signals to the individual speakers at speaker level, and has an additional output (which looks to me like an additional integral amplifier) for the sub woofer. I replaced the head in my 94 and the new head only had speaker level outputs. I got a box from Crutchfield.com to convert speaker level to line level, used the adapter plug that came with it and it works great. You do have to adjust the line levels at the adapter so you don't overdrive the amp. It takes a few minutes to get it right, but sounds great when your done.

My factory install had a wire from the original head which signals the amp that the radio is on or off. My new unit is also equipped with a signal, or amp on/amp off wire.
 






I recently added a factory sub to my aftermarket stereo. I took the whole box into the local stereo shop and was able to find a small amp to fit next to the front speaker amp. I had to do a little trimming so the wires would slide behind the front amp. I was then able to use the RCA cables to run my sub. The front speakers still use the factory amp through the plug in the dash. They are just spliced in with the colored speaker wires on the stereo.
 






If this helps, they do make "bypass kits" for the factory amp, as well as a connector to interface with it. Thy bypass connects the input cable to the output cable at the amp and the speaker output of the head to the amp cable.

This is terrible because now you are running speaker signal over really thin wires inside that multiwire cable, which is not nearly ideal.

The interface connector goes from the speaker outputs on the head to the amp cable. There is no circuitry involved, it's straight through. So you CAN feed speaker level signals to the amp apparently. My truck was this way, there was a 45wx4 JVC cassette deck feeding the factory amp. It worked but is not the best thing for audio quality.

Honestly I would strongly suspect that the amp in the factory system is worse than the one in the head, and the best thing to do is to bypass it. You have the sub though, and we want to save it....

I have a amp/sub box combo from a 1st gen limited right here in my basement. Looking at it there are two amps. One is for the sub, the other is for the remaining speakers and contains the crossover. There is a connector at the bottom of the sub amp which has power and speaker connections, and one at the top with the input from the crossover.

Presumably you should be able to use only the sub amp by connecting it to the sub out on the head, and then rewire for the door speakers to the head. I say presumably because I have not tested running a sub out into that amp's input connector.

You could also replace the amp and sub with higher quality stuff as well...
 






Hi Tedj. Are there any adjustments for the crossover freq. on the main or sub amp?
 












Thanks for all the info guys. Right now I have the line level connections and remote wire all soldered together and I still can't get this amp to work. I have even tried different sources besides my head unit and still nothing. The only sound I can get is a slight pop when I hook up the other side of the RCA cable. Right now this is all just a temp set up because I normally run an aftermarket sub and amp so if I can't this to work then its whatever but I am curious as to how it would sound.
 






Are you sure that you have the wiring correct? Keep in mind that the connector kits have you feed speaker level signal into the amp... so maybe line (RCA) will not work?
I was trying to find more about the expected voltages etc but the ford manual is not written with the intent of hacking around the system. Not much info...
These are the diagrams that they show....

Picture_225.png


Picture_226.png
 






What is the make/model numbers of the head unit you are using?
You should not have the (usually)blu/wht remote wire connected to the speaker outputs. The "remote" or blue with white stripe wire should connect to the remote output of the head unit and tells the amp to turn on when the radio is on and turn off when the radio is off.
But if you can provide the make and model number of the head unit I will try to find a diagram that will tell you what wire goes to what.
 






I have a 91 sport that came with the one amp and no sub. I got it and someone had already put the amp bypass harness in and a cheapo sony head unit in with a wire harness adapter. I took the sony out and put in my newer explod head unit and explod 4x6's in all the factory spots. I then went down to the junk yard and pulled a factory JBL sub setup from a 91 XLT. I took the amp bypass out as well as the original amp. I ran a power and ground to the sub amp and hooked everything up and it sounds great. Ive carved out the old six inch hole and added a JL audio 8" sub. And for the factory amp it sounds good. Its not staying but for a cheap thump it was worth what I paid. No splicing was required. The harness behind the head unit runs everything fine. Yes the factory amp system has a remote wire. It does all run on high output lines. Your amp isnt working because you need the harness connected.
 






Subwoofer Wires

Hi guys, I have a 96 Explorer Limited and can anyone tell me on the factory subwoofer, theres a black wire with a green stripe and a black wire with a white stripe. Which one is positive?
 






If your just looking for polarity on a speaker, use a standard AA battery. Touch the speaker wires to each end of the battery. If the speaker moves in then you have the negative wire on the positve of the battery. If the speaker moves outward then you have the positive to the positve. Copy copy?
 






I have a 91 eddie bauer with the 2 amp jbl sound system. I bought the harness to integrate into the factory amps(purchased from crutchfield) to the Eclipse head deck. The front door and back door speakers work, but the sub does not. I've tried a different sub with the same results. I'm guessing I have to do the whole RCA splicing ordeal? My head deck has 3 sets of 5v preamp outputs. 2 of which are being used by the harness I got from crutchfield(front/rear) leaving the 'non-fader' pre-out for a sub. Any ideas?
 






Give Crutchfield a call.

I have a 91 eddie bauer with the 2 amp jbl sound system. I bought the harness to integrate into the factory amps(purchased from crutchfield) to the Eclipse head deck. The front door and back door speakers work, but the sub does not. I've tried a different sub with the same results. I'm guessing I have to do the whole RCA splicing ordeal? My head deck has 3 sets of 5v preamp outputs. 2 of which are being used by the harness I got from crutchfield(front/rear) leaving the 'non-fader' pre-out for a sub. Any ideas?

I had a similar problem with my '94. I called crutchfield and they were able to help solve my problem. I would try them since the harnesses may be different.

Hope this helps.
 












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