I have a 1987 BMW 325i. Im trying to install a Kenwood head unit. It previously had a sony after market head unit. The old head unit died.
The connectors don't fit each other exactly, so I cut some of the connectors and am making a direct connection.
Here's the problem. I can get the power/memory/pwr attenna/ground connected and the radio turns on fine. However, there are only two speaker wires that were connected to the old head unit. One + for the right front and One+ for left front. Previously all 4 speakers worked. I tried connecting just the FR+ FL+ from the dash to the head unit as it was connected before, but I don't get any sound.
I checked the new head unit by directly connecting another speaker to it, the head unit works fine. I cant figure out how to get sound! Has anyone encounterd this sort of problem before? Please help!
Replies (5)
swez on 09/21/2005 18:49:05
Each speaker has 2 wires. One is Pos and the other is Neg for that given speaker on a given channel off the HU. Need to ID all speaker wires and what location they feed to.
Best way is a small 9 volt battery, connected to each speaker wire set. When you hear a pop sound as you touch each speaker wire set to battery, note wire color and location of the sound and connect to HU speaker outputs as noted in the manual. Hopefully, this will get you back in biz in short order.
Swez
ttocs on 09/22/2005 21:59:19
sounds like you had a common ground radio in there. They don't make many of those anymore.
Idunno if these are right as I am getting them from a book that I have found problems with before, but this will give you something to start with. Do the test the swez explained, you can use any battery from AA up.
white----------drivers+ front
black-----------drivers -
white-----------drivers + rear
black-----------drivers - WAIT A MIN..............
Ok, now I see our problem, your car is common ground............. What this means is that there is one + wire for the left and the right(or it can be front and rear), and they at some point will go to the same ground. Most radios will have a + and a - wire for each speaker. You can add a common ground radio to a floating ground wiring system, but you cannot do the opposit. I am sure you are good and confused by this point as reading back over it, it sounds strange to me too....
Can you get a pic of what you have in the dash? What we will need to do is find where the grounds become common, and then seperate them so they are now floating ground. The very well could be common right in the dash and it may not be a big deal. However they may have put that sony in there as it was also a common ground radio, and seperating could be a pain... If you could get pics we/I could help better.
UKinstaller on 09/23/2005 00:23:00
ttocs, the common ground radio has returned!! unfortunately, the new 2005 Jeep Grand Cherokees with premium sound is a common ground system. can you believe that??
new dodge durangos are common ground, too. i put a head unit and an amp/sub in a 2005 dodge magnum yesterday. i thought it too was going to be common ground, but fortunately it wasn't.
-UK
ttocs on 09/23/2005 03:23:16
NO WAY!!!!!!!!! Man i'm glad I got out then... It never seemed that two cars having the same make and model had the same wiring. I can recall tracing many speaker wires on mustangs and chryslers to find and seperate the grounds but they would never be the same.....
swez on 09/23/2005 11:10:10
If the car speakers are wired for a common ground system and you wish to change the stock radio to an aftermarket (floating ground system) This can be done by running new "paired" speaker wires to each speaker location. Each speaker will need a + and - wire to feed it. The - connection on stock speakers (or aftermarket) must not be the same ground as the body/chassis. This can damage the new HU.
From previous experience on a 1980 BMW 320i, the stock speakers and HU were really lame. They used a cheap Blaupunkt radio and speakers back then. Hopefully, BMW has upgraded a bit since then. But if not, there is no reason you cannot upgrade now.
However, it may be a good idea to have a Pro do the work for you. This may not be easy/wise for the average DIY'er to do alone.
Swez
The connectors don't fit each other exactly, so I cut some of the connectors and am making a direct connection.
Here's the problem. I can get the power/memory/pwr attenna/ground connected and the radio turns on fine. However, there are only two speaker wires that were connected to the old head unit. One + for the right front and One+ for left front. Previously all 4 speakers worked. I tried connecting just the FR+ FL+ from the dash to the head unit as it was connected before, but I don't get any sound.
I checked the new head unit by directly connecting another speaker to it, the head unit works fine. I cant figure out how to get sound! Has anyone encounterd this sort of problem before? Please help!
Replies (5)
swez on 09/21/2005 18:49:05
Each speaker has 2 wires. One is Pos and the other is Neg for that given speaker on a given channel off the HU. Need to ID all speaker wires and what location they feed to.
Best way is a small 9 volt battery, connected to each speaker wire set. When you hear a pop sound as you touch each speaker wire set to battery, note wire color and location of the sound and connect to HU speaker outputs as noted in the manual. Hopefully, this will get you back in biz in short order.
Swez
ttocs on 09/22/2005 21:59:19
sounds like you had a common ground radio in there. They don't make many of those anymore.
Idunno if these are right as I am getting them from a book that I have found problems with before, but this will give you something to start with. Do the test the swez explained, you can use any battery from AA up.
white----------drivers+ front
black-----------drivers -
white-----------drivers + rear
black-----------drivers - WAIT A MIN..............
Ok, now I see our problem, your car is common ground............. What this means is that there is one + wire for the left and the right(or it can be front and rear), and they at some point will go to the same ground. Most radios will have a + and a - wire for each speaker. You can add a common ground radio to a floating ground wiring system, but you cannot do the opposit. I am sure you are good and confused by this point as reading back over it, it sounds strange to me too....
Can you get a pic of what you have in the dash? What we will need to do is find where the grounds become common, and then seperate them so they are now floating ground. The very well could be common right in the dash and it may not be a big deal. However they may have put that sony in there as it was also a common ground radio, and seperating could be a pain... If you could get pics we/I could help better.
UKinstaller on 09/23/2005 00:23:00
ttocs, the common ground radio has returned!! unfortunately, the new 2005 Jeep Grand Cherokees with premium sound is a common ground system. can you believe that??
new dodge durangos are common ground, too. i put a head unit and an amp/sub in a 2005 dodge magnum yesterday. i thought it too was going to be common ground, but fortunately it wasn't.
-UK
ttocs on 09/23/2005 03:23:16
NO WAY!!!!!!!!! Man i'm glad I got out then... It never seemed that two cars having the same make and model had the same wiring. I can recall tracing many speaker wires on mustangs and chryslers to find and seperate the grounds but they would never be the same.....
swez on 09/23/2005 11:10:10
If the car speakers are wired for a common ground system and you wish to change the stock radio to an aftermarket (floating ground system) This can be done by running new "paired" speaker wires to each speaker location. Each speaker will need a + and - wire to feed it. The - connection on stock speakers (or aftermarket) must not be the same ground as the body/chassis. This can damage the new HU.
From previous experience on a 1980 BMW 320i, the stock speakers and HU were really lame. They used a cheap Blaupunkt radio and speakers back then. Hopefully, BMW has upgraded a bit since then. But if not, there is no reason you cannot upgrade now.
However, it may be a good idea to have a Pro do the work for you. This may not be easy/wise for the average DIY'er to do alone.
Swez
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