mark vi amp wiring - need to bypass the amp

[sly]

my google fu fails me. I know there's some premium sound diagrams on this site somewhere for the early 80s boxen, but I can't find them. Going with an aftermarket stereo and I need to make a bypass cable unless someone knows of one for the round pin plugs for the ?-82 Mark VI. All I can find is the 88+ premium sound bypass cable.

[gadget73]

in a practical sense there is no spoon. Its the old common ground BS that you can't do much with. I strongly suspect you're gonna be stuck running new wiring to the speakers directly.

[sly]

there's 8 separate wires going back to the amp... and 8 separate wires going out to the speakers... if the speakers themselves are not grounded to the car... it would work fine... it looks like the power is a DC offset fed over the 4 positive speaker wires via the premium sound switch. I just need to know which wire is which for the pass-through so I can cut the amp out of the loop. I guess I could just ring out the amp and the wires from the front to the trunk and make sure.

If I figure it out... I'll post pinouts.

[sly]

ok... here's why there's no bypass cable for the football amp... there's no need. The signal goes back to the amp, and returns to the front to be overlapped with the signal out to the speakers. (I think).

so the way to bypass the amp... un-plug it. that's it. Use the adapter kit for aftermarket stereos and just plug in. The amp specific connections in the dash are not compatible. I also disconnected the cables in the trunk as well just to make sure that the amp doesn't get power at all, but all the wires are still sitting there.

This is for the 4 channel amp with the round pins in the rectangular harnesses. I'm sure it's similar for all of the old football amps, but since I don't have access to the actual wiring diagrams, I can't say for sure.

[gadget73]

hm, intersting. They must be using some different stuff than the mid 80s Towncars then. Townies had 3 wires from the radio to rear speakers, left, right, and common, and 3 wires to the amp. From the amp to the front speakers it has 4 wires, making a bypass effectively impossible.

[sly]

yeah... I think the change happened in 83 or 85... this would be for the older ones. with 8 wires per harness on the amp and a 6 and 8 slot harness in the dash for the premium side.

The speakers are in need of replacing up front... I think cone rot in the doors... but the rear speakers sound good. I'll replace them all eventually though.

[sly]

just to close up this thread... replaced all the speakers, removed all the premium sound stuffs (amp and wiring). No more need for amp bypass info since just disconnecting the amp bypasses it.

[porschpow]

Sorry to dig up the old post, but im going through the same thing now. I do have the factory amp on my TC 1989. Don't you have to disconnect the power supply too?? How did you run your new stereo?

[tjc78]

Mark VI amp setup is nothing like your 89. Full response coming in your other thread.

[sly]

in the Mark VI, the amp uses the speaker level outs from the factory head unit. removing the cable that goes to the amp gives you the exact same plug as the line coming FROM the amp. So just removing the amp section from the circuit effectively bypasses the amp. And yes, way different from (and inferior to) the setup in the 89.

[gadget73]

The 89 amp has a bypass harness available, but the feed to the back is some mighty skinny wire. There is an adapter that lets you run the stock amp with an aftermarket head unit by connecting to the RCA outputs. One of those on each end (I think the amp end is the same as the radio end) would give you a nice 4 channel feed to any aftermarket amp you want to use in the trunk. The speaker output wires and the remote turn-on wire are already in the stock harness. Just feed it a heavier power cable and you're good to go.

[tjc78]

There is an adapter that lets you run the stock amp with an aftermarket head unit by connecting to the RCA outputs. One of those on each end (I think the amp end is the same as the radio end) .

The amp end is actually a different connector, it's a rectangular plug. What you suggest could still be done with an old set of RCAs and the amp bypass cable. In my 89 I ran new RCAs, but did use the speaker wires. I wish all cars had that setup.

[gadget73]

come to think of it, I do remember that its a rectangular plug. My Mark VII has that setup, but the Towncar does not. It used this funky semi-common ground thing and only had the amp on the front speakers. My front speaker wiring is actually the original wiring from the car though, which helped get rid of some mess under the dash.