Previous owner must have just attached wires until there was sound from 4 speakers! Unfortunately I don't even know which radio system was in the car originally. Fader switch has a total of 8 input wires, BLACK, BLUE, YELLOW, GREEN, BLK/WHITE, BLUE/GRAY, BLK/PURPLE & BLK/GREEN. Don't actually know if the fader was even in play after the hack job!

Pulled radio (JVC KD-GS820) and found a horrible mess. Appears there were a total of 5 (?) factory connectors: 1st one is obviously the antenna. My car has the dash antenna switch, which currently works perfectly, BTW!

2nd one is a black oblong/rectangular(?) plug with a brown wire input at the far left position & a brown wire that connects to the 4th position, then an empty space, then a green wire in the middle, the brown wire from the far left into the 4th position, and two wires on the far right, both brown with a blue stripe, the exiting wire has some kind of square plug attached. I believe this is/was the power input plug on the original radio.

THIS WAS NOT CURRENTLY HOOKED UP TO ANYTHING! But the radio had sound.

The 3rd one is a black sheath with a single blue wire: I'm led to believe this is the antenna.

4th has 4 wires: BROWN, RED/WHITE, BLACK/GRAY & GRAY/BLUE wires coming out of a black sheath.

5th has a total of 5 wires coming out of another black sheath: BLUE, GREEN, BROWN and two BLACK WIRES, one of which has a spade plug and then continues on (before it was hacked off).

I have a new JVC unit to install that has what I would consider to be the "normal" type harness: a total of 13 wires.

A) BLACK = Ground
B) YELLOW = 12v+ constant
C) RED = to an accessory 12v+ terminal
D) BLUE/WHITE = to antenna
E) ORANGE/WHITE = to illumination

then the actual speaker connections,

WHITE (+) & WHITE/BLACK (-) = Left front speaker
GRAY (+) & GRAY/BLACK (-) = Right front speaker
GREEN (+) & GREEN/BLACK (-) = Left rear speaker
PURPLE (+) & PURPLE/BLACK = Right rear speaker

From a day on the SEARCH function I'm pretty sure the single BLUE wire in the black sheath 3rd is the antenna, so = D) BLUE/WHITE to antenna on the JVC.

The RED/WHITE from the 4th should be 12v+ constant = B) YELLOW on the JVC.

BROWN from the 4th should be the GROUND = A) BLACK on the JVC.

This leaves C) RED to an accessory 12v+ & E) ORANGE/WHITE to illumination on the JVC.

Plus the 8 speaker connections.

Any assistance would be greatly appreciated.

p.s. WHY, OH why, couldn't the MB engineers used a little longer wires on the fader & window switches?

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'91 420 SEL @ 199K, '92 SVX @ 181K, '93 SC400 @ 86K, '93 Kaw ZX-11 @ 30K, '87 F250 @ 181K , 2001 Valkyrie Interstate @ 6K, Y2K Honda NightHawk 250 with 1.5K, '88 420SEL I.@ 179K & the 2nd latest, an '88 420SEL II.@ 210K runnin' parts car, '85 F150 300/NP435

More reading seems to indicate the BLACK/GRAY from the 4th sheath is switched 12v+ and should be connected to C) RED to accessory on the JVC, and that the GRAY/BLUE would be the dimmer connection, so = E) ORANGE/WHITE on the JVC.

Can I go directly from the JVC harness to the 8 wires coming out of the fader? Wouldn't these be the speaker wires, or is it a 4 in, 4 out situation?

I know it would help to know what radio it had to begin with, but...

HELP (AGAIN?) !

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'91 420 SEL @ 199K, '92 SVX @ 181K, '93 SC400 @ 86K, '93 Kaw ZX-11 @ 30K, '87 F250 @ 181K , 2001 Valkyrie Interstate @ 6K, Y2K Honda NightHawk 250 with 1.5K, '88 420SEL I.@ 179K & the 2nd latest, an '88 420SEL II.@ 210K runnin' parts car, '85 F150 300/NP435

Have located a wiring diagram (pg. 135 '88 to 8/'88 production) that shows a GREEN and BLUE wire going from the head unit back to the fader as the left and right "pre-amp outputs", then BLACK/WHITE, YELLOW, BLACK/VIOLET (I mistakenly described this a "purple") and BLACK/GREEN wires going back to the amplifiers as LF, LR, RF & RR (+) speaker inputs.

That leaves the two BLACK wires on the 5th connection I described in my original post (which, incidentally are connected as two spade terminals, one male and one female) as the as the left and right "on/off input" & the BLUE/GRAY as the switched 12v+... This accounts for the 8 wires in the fader...

I hope?

If I were to try and by-pass the amps without running new wires to the amps/speakers it would seem to me that running all the speaker grounds to the TWO BLACK and the various (+) speaker wires from the new JVC unit ( WHITE JVC = LF, GREEN JVC = LR, GRAY JVC = RF, & PURPLE JVC = RR) into the corresponding wires at the fader and using the JVC head unit for the front/rear fader function? This would mean NOT connecting the GREEN & BLUE wire on the MB loom. But what about the various speaker grounds?

This diagram shows a BROWN WIRE coming out of the pre-amp described as "signal ground" and becomes a BLUE and a VIOLET wire going to the amps where it again is described as "signal gnd". Should this not be consistant? It is, after all, hardwired.

Isn't GROUND basically = GROUND, regardles of the signal path?

HELP III !!!

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'91 420 SEL @ 199K, '92 SVX @ 181K, '93 SC400 @ 86K, '93 Kaw ZX-11 @ 30K, '87 F250 @ 181K , 2001 Valkyrie Interstate @ 6K, Y2K Honda NightHawk 250 with 1.5K, '88 420SEL I.@ 179K & the 2nd latest, an '88 420SEL II.@ 210K runnin' parts car, '85 F150 300/NP435