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Old 3rd January 2018, 14:08   #1
rrr
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Default Symphony not communicating with CD changer

I bought a low mileage 75 1.8 last year with a Harmony radio in it. I decided to upgrade to Symphony and add a glovebox mounted CD changer XQU100430 which I took from a donor car and which was working faultlessly there. I bought a blue mini ISO connector, cut away the connector from the Symphony-CD changer wiring and soldered the blue mini ISO to the wires according to the diagram I found on this forum (unfortunately picture not available any longer). When I connect the changer to the wiring, it "wakes up" and seems to scroll through the carriers in search of discs which can be heard (I did all the testing with "genuine" CDs, no copies, so the changer should face no difficulty with reading the discs). However, the Harmony headset does not recognize the CD changer during this process and when TAPE/CD button is pressed the display only says "NO TAPE". As I have another changer of the same type, I tested it only to get the same result. Then I had no energy to go further and ran the car using radio/tape only. Then I got a brand new Symphony unit and decided to go back to the problem during Christmas holiday. I removed the home-made wiring, checked all the wire colours only to find that everything is as the picture shows. Installed the new Symphony headset, connected the CD changer, same result as before. Connected the second CD changer, same result... Not to forger, the steering wheel control also does not work since the beginning (wires also connected according to the picture).
Would anyone have an idea what the problem is? What have I done wrong? I know a CD changer is an obsolete thing, however would like to keep the car equipped with the original audio system and not go for something contemporary (and probably more sensible...).
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Old 3rd January 2018, 15:52   #2
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I would check that you have a K Bus connection between the changer and

the Symphony, you also need to make sure that the above K Bus connection

is connected to the car's K Bus circuit.

The 75 relies on the K Bus circuit to enable the Symphony to "Talk" to the

changer.

The K Bus is connected to the Symphony via pin 19 on the Blue mini ISO

plug.

The K Bus circuit can be found on various connections in the 75, the closest

to the radio is on the back of the IPK.

It is possible you just have a loose White/Red/Yellow wire and this needs to

be attached to the wire on pin 19 blue mini ISO.



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Old 6th January 2018, 11:50   #3
rrr
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Thanks for the advice! Today I finally got to the job, unfortunately with no success until now. First I checked the K-Bus connection of the Symphony head unti only to discover that the BMW plug to ISO from eBay had this pin missing. I cannibalised one pin from another eBay BMW plug to ISO and lead a wire to the K-Bus socket (where all the K-Bus wires meet). I used a wire with a connector from a donor car, so I was quite happy with a "clean" result and hoped I found the problem. Checked the wiring between head unit and CD changer to confirm that the K-Bus wire is connected to position 19 in the blue mini ISO.
However, after doing all this nothing changed. The head unit keeps showing NO TAPE message when CD/Tape button is pressed and does not react to the steering wheel control.
I even tried to check the Radio unit using TOAF, but it has not found any Radio unit.
Any hints are highly appreciated...
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Old 6th January 2018, 13:17   #4
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It still sounds as if you have no K Bus connection to the K Bus circuit in the car.

Pin 7 on the BMW plug is the K Bus connection.

You have established that the K Bus [White/Red/Yellow] is connected between

the Symphony and the CD changer, now you need to make sure that the K Bus

wire between the radio and CD changer is connected to the cars K Bus circuit.

If you look at the back of the IPK [speedo] you will see a White/Red/Yellow

wire in one of the plugs.

Connect your Radio/CD changer K Bus wire to the K Bus at the back of the

IPK.

You may be able to find a White/Red?Yellow elsewhere in the 75, any of

these will work ok.



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Old 6th January 2018, 19:58   #5
rrr
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Thank you for the picture and advice. It also seems to me that head unit + CD changer are not connected to the car, but I do not understand why as I have already fitted the empty hole No. 7 of BMW plug with a pin, soldered to a wire connected on its other end to the "center" of all K-Bus wires (a grey plastic box which connects together all the K-Bus wires situated above passenger (LHD) feet). Really cannot understand why the head unit + changer remain unconnected to the K-Bus
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Old 8th January 2018, 09:15   #6
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Update - problem solved. After checking all the connections according to the picture above and finding all was connected correctly, I tried with the new head unit. Both CD changer and steering wheel remote control work perfectly with it. So I expect there was something wrong with the head unit I used first. Anyway, thanks for help
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Old 27th January 2021, 01:05   #7
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Hi, does anyone have the wiring diagram for the cd changer plug for the harmony, I need to convert mine to iso
many thanks

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