Ford Factory Amp Bypass

Hello all,

My problem is this. I recently purchased a '91 Grand Marquis, in decent shape, for a good price. The previous owner even left his after-market cd deck and all four speakers. However, the old unit was wired improperly, the tuner had static on a lot of channels, and the cd functionality was sporadic at best. So, I purchased a new deck and proceeded to install it.

After having problems (turned out to be a fuse) I managed to start hooking up the unlabeled speakers through trial and error. There are 3 sets of non-factory speaker leads that do NOT go through the harness; these I hooked up first. Some idiot had run his own wire, which is fine, but only ONE set went to the back speakers (rt channel) and was spliced over to the left rear. *sigh*

So, instead of running another wire, I thought I'd use the factory harness on the deck end and find the other end in the trunk. I found the corresponding left rear and hooked it up, and nothing happens (the wiring was still being routed to the amp but I believe power has been cut from it.) So, I need to bypass the amp, at least for this one speaker -- but I'm too cheap to buy the stupid cord. Is it possible to bypass it without the amp bypass harness? I sure hope so, 'cause I already cut all the wires My hope is to take the l.r. wires from one side and crimp them to the l.r. wires on the other. Problem is, one side is all speaker wires while the other side seems to be acc power, switched power, ground, and only one side (+?) for the four speakers. However, that little bypass thingy can't possibly be doing anything terribly different. Please Help!

try finding a wiring diagram and actually useing the factory amp. if that doesnt work, find the factory amp and splice into it, thats all the bypass harness will do, but its much easier with the harness than trial and error. if all else fails, rewire each speaker. good luck.

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I tried splicing into the speaker wires on one side, it didn't work. The only thing I can think is that I spliced into the wrong side -- but it's the only side with wires that are the same as the ones on the speaker harness; not solid colors, but black w/ green stripe and pink w/ green stripe. Very disctinctive. So I assume I am to splice into the other side, but the wires aren't similar, and there appears to be 2 powers, a ground, and then 1 wire per speaker, so I'm lost. My friend has an '85 Merc and my have a service manual for it, I'll try that if it comes through. If anyone else has a manual for a '91 Merc laying around, I could probably use the diagram (can't find it anywhere.) In the meantime, if anyone has any more advice, it's much appreciated :)

Here is the wiring diagram for your car. The reason it seems there is only one wire per speaker, is because indeed there is only one wire.

Your car has what is called a "common ground", in which all speakers share the same ground, and without using the factory amplifier,  you have to run new wires to each speaker.

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Wow, thank you Chad I was about to give up anyway, but I hate giving up. At least now I know it's not possible unless I wanted to hook up that amplifier, and then there's the probability of the audio being overdriven anyway. I suppose I could have bought the bypass harness, but I'd rather run 1 wire than drop the dough on that anyway. Now, off to get some speaker wire. Thanks again ss-installer and Chad7n7.

OK, I ran the wire and it wasn't bad at all. In fact it was quite easy. Stereo sounds great now. Now, to figure out how to operate and program this stupid aftermarket car alarm; my front door power locks won't work :(

(No need to reply, I'll make a new post in the proper forum about that if I can't get it figured out)