98 s70 - new alpine headunit, rear door speakers inop

[normtodd]

Greetings all - I apologize in advance for this long post, but ill go into detail as to minimize followup questions

ok - so i inherited a 1998 volvo s70 that came with the stock volvo hu the sc-813. the car has 8 speakers (2 in dash, 2 in front doors, 2 in rear doors, 2 on rear deck.

when i got the car, the only speakers that were working were the driver's dash speaker and the drivers door speaker. not good. i surmised that one of 3 things was happening:

1) the amp in the sc-813 had gone bad
2) all of the speakers were bad except for the working speakers in the drivers dash and drivers door.
3) there was some catastrophic wiring issue

i was given a friends old Alpine CDA-9856, and figured i would install that and see what happened.

I ordered from crutchfield the appropriate harness to connect into the plugs that went into the sc813. i ordered from ebay an alpine wiring harness and soldered/heatwrapped it to the 2 volvo harness from crutchfield. so far so good.

i hooked everything up and it all the speakers worked (and sounded great) except for the rear door speakers.

in reading the various forums, i believe that the wiring for the stock system was that for the rear speakers, the wiring was in parallel to the 2 sets of 8 ohm speakers, so as the headunit "read" the rear speakers as a 4 ohm net set (so to speak).

if there was a wiring issue with the harness, i imagine I would not get any sound from the rear deck at all.

the logical part of my brain says I should leave well enough alone and keep it as it is now. the sound is so much better that right now I cant logically justify doing anything else.

but my gut just wont leave it alone.

for what reason would the rear deck speakers work like a champ and the rear doors not work at all?

for reference, the CDA-9856 claims to power output 18 W RMS x 4 so this should (i think) work fine.

what am I not thinking of here?

thanks in advance for everyone's help - im dying to figure this out.

[BEJinFbk]

I have a suggestion, but you may not like it.
Anytime I get involved with a car stereo with "Issues",
my first step is confirming that everything works.

Starting with the "Car Side", I plug in the adapter and check all
the power, ground, illumination leads and speakers for correct operation.
Power, ground and illumination can be checked with a meter.
For speakers, a 1.5 volt battery will answer the basic Go/No Go question.
You should hear a solid POP when connecting the battery.
( You can also confirm polarity with this method.
The cone will move OUT if positive is positive.
It will move IN if you have polarity reversed.)

For the deck? A 12 volt power source and a pair of speakers will get the job done.
ALWAYS bench a used deck before you even look at the car. ( Ask me how I know! )

Here's the part you won't like... You'll have to cut and resolder...Sorry.

[normtodd]

fair enough and a sound suggestion - it will definitely be my MO for the future before i install anything. lesson learned.

but before i start cutting the harness to test before resoldering etc, let me ask this:

i found this from bay 13 over at volvospeed this diagram that breaks out what each lead does that connects to the head unit

http://www.volvospeed.com/Repair/radiocon.php

which states that:

the 14 pin "A" connector:

1A = Dash Left Speaker +,
2A = Dash Left Speaker -,
3A = Antenna +,
4A = Battery + 12V,
5A = Not used,
6A = Ground,
7A = Dash Right Speaker +,
8A = Dash Right Speaker -,
9A = Not used,
10A = Rheostat +,
11A = Rheostat Ground,
12A Battery + 12V ,
13A = ACC +,
14A = Ground.

Breaking down the 10 pin "B" connector:

1B = Left Rear Speaker -,
2B = Left Rear Speaker +,
3B = Left Front Door Speaker -,
4B = Left Front Door Speaker +,
5B = Right Rear Speaker -,
6B = Right Rear Speaker +,
7B & 8B = Not used,
9B = Right Front Door Speaker -,
10B = Right Front Door Speaker + .

"The rear speaker wires supply the rear hat shelf and door speakers if installed, wire coloring is the same for the hat shelf and the rear door speakers."

so as i read this, the wiring in question is from the B connector and specifically 1b, 2b, and 5b, 6b and are the leads to look at since everything else works; that those leads feed the rear doors AND the rear deck (called hat shelf by bay 13).

so the plan would be to snip and test with a battery wires from 1b-2b and 5b-6b (corresponding to green/green-black and violet/violet-black) that i get a "pop" from both the rear doors AND the rear deck speakers.

does that sound like the appropriate gameplan/next step?

also most importantly i suppose before i go any farther, is the spec detailed above from bay 13 still applicable for the 1998 s70?

all the best and thanks in advance

[normtodd]

so i am sheepishly posting this followup, but wanted to bring this issue to a close.

it turns out that there is no sound from the rear door speakers because there are no rear door speakers.

I checked the original window sticker that was in the file of service records and it indeed reflects that only 6 speakers are installed.

now i suppose the next step is to install speakers in those doors!

thanks for all. nothing to see here, move along.