240 aftermarket radio issues

Old 12-21-2018, 12:23 AM
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Default 240 aftermarket radio issues

Hello everyone,

I recently purchased a Volvo 240 wagon DL which had the radio missing, according to the previous owner it was stolen. Because of this, I decided to get a cheapo aftermarket stereo off amazon so I could listen to something while sitting in traffic. After opening up the guts of the interior I found what seemed to be the old harness which had been cut off. Using a multimeter I identified the +12 wire, the front left and right speaker wires, and the ground. After some more digging through cables, I found what seemed to be some pretty sketchy looking wires which through testing hooked up to the rear left and right speakers. Also, I found, tucked away behind some carpet, the antenna wire.

Using the diagram provided I hooked up the wires in order for the radio to work, I taped into the cigarette lighter positive as an "ignition turn on" so that the radio wouldn't always be on. After finishing up I decided to hook up the front left speaker and test out the system. Once the car was put into the electricals on position (1 before the position where the engine would start cranking) all the lights turned on and so did the radio, happily I clicked the on button and let the radio load for the second, then it started showing that it was playing music yet nothing was coming from the speaker.

Disappointed I took the multimeter and went through to test the wires to the speakers, I was only getting around 1 volt or so. I went and tested the actual pins on the head unit and to my surprise, the pins for the front two speakers only displayed 1 or so volts, whereas the rear two showed about 10. Thinking to myself that this is what I get for getting a cheapo head unit reconnected the speaker to rear left set of connections and the same problem happened, now all of the pins were showing barely any voltage.

Next, I thought it was the head unit in general not being powerful enough or just cheap and bad so I bought a 40 dollar one that came with its own set of speakers so I could be sure that they were the right impedance and everything. but the same issues happened, before plugging in the speakers I tested the voltage and I was getting a strong 10 volts. After I tried hooking up the new speakers the voltage went down to 1 and would not go back up even if I disconnected everything and tried again. I thought that maybe you need to have both speakers hooked up at the same time for some reason, this did not help either. After all this testing and frustration I removed the head unit and it was warm were the harness plugs into the head unit. I am not sure if I blew something or broke it, and any help would be wonderful.

Some more details:
- The speakers are not blown, I tested them with a double a battery from which they made a pop sound.
- The fuse of the back of the head unit is also intact
- When I bypassed the dodgy wiring by connecting the speaker directly to the short wires from the head unit the same issue persisted.
- The speakers never made any noise or indication that they were working other than when I tested them with a double a.

Any help at all would be appreciated, I have had the poor thing sitting in my driveway for a couple days now with the interior ripped apart. What started out as a seemingly one evening cheap project has spread to much more time and money consuming one and at this point, I just want to get it working so I can put everything back together again. Thank you.
Old 12-21-2018, 02:02 PM
Join Date: Mar 2012
Location: Ridgefield, CT
Posts: 4,794

do you have an old boom box or stereo that you can use to wire up to the speakers or perhaps an old speaker to hook to the head unit. Geez, where's Radio Shack when you need em? I'd start by testing the individual components - if the head unit was new coming out of the store then I'd be making sure there is connectivity to the speakers and that the wiring is complete. Also make sure the radio chassis has a solid ground to the car.
Old 12-21-2018, 02:21 PM
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Location: 37 North on the left coast
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there shouldn't be any measurable voltage on speaker wires except blips of audio frequency AC when its turned up really loud.

I'd be verifying the radio is getting proper power, most aftermarket stereos need two power wires, a yellow one thats always powered, and a red one thats powered when the vehicle is in 'aux' or 'on', and they need a good ground (black). often its the red wire that is really powering the radio, while the yellow one is just powering the station and settings memory when the car is off, but I've seen some that were the other way, the yellow was the 'real' power to the radio (and memory), while the red just acted as a control circuit to tell the radio its OK to turn on.

Last edited by pierce; 12-21-2018 at 02:32 PM.
Old 12-21-2018, 02:31 PM
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Join Date: Oct 2010
Location: 37 North on the left coast
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you don't say what year this car is, the wiring changes year to year... so I arbitrarily checked the wiring for a 1987/1988 as thats what we had...

a 87/88 240, the radio had a 9 pin 3x3 block connector.... JIS below refers to the japanese standard for stereo wiring

pin 1, green, wasn't connected to the stereo just the antenna, and provides the antenna with always-on power. you can tap this to power the JIS yellow
pin 2, yellow-black, is switched power, should go to JIS red wire
pin 3, red, is antenna control, should go to JIS blue wire
pin 9, black, is ground, and should go to JIS black

pin 4, yellow-white, is left front speaker +, JIS white
pin 7, white, is left front speaker -, JIS white-black
pin 5, grey-white, is right front speaker +, JIS grey
pin 8, grey, is right front speaker -, JIS grey-black

the JIS

most volvo 240's did NOT have rear speakers wired from the factory, although some later ones got dealer added speakers
Old 12-24-2018, 10:21 AM
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Join Date: Dec 2018
Posts: 2

I fixed it!

After messing around I got the super cheap radio to work outside the car in the engine bay, but only sometimes and if you moved it even slightly or pushed on the wires it would not work. The other one I could not get to work at all. The solution was to buy yet another radio! As they say third times a charm. I bought another one for around 40 dollars and it worked perfectly when I installed it.

Basically, if everything should be working and you check it 5 times but it's not. Then the radio is bad... and if your buying cheap i guess there are a lot more lemons then I thought.

Thanks for the help!
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