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E30 OEM Radio - CD Changer Pin Diagram Needed

Discussion in 'E30 (1984-1993)' started by Brian A, Jan 10, 2009.

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    Brian A

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    My 1991 318i has a factory radio with a round plug in the back for connecting a trunk-mounted CD Changer.

    I need a wiring diagram for this plug, i.e. what are each of the pins for?

    I expect that two of these pins are plain line-level inputs from the CD changer. If this is the case, plus knowing the signal pin that would fool the radio into thinking a CD changer is connected, I should be able to install a line-level phone jack input fairly easily. This would allow me to play my iPod through the factory radio.

    First I need a wiring diagram. I maybe using the wrong key words in Google, but I cannot find one posted anywhere.

    Here are photos of the plug I am referencing and the faceplate of the unit installed:

    dunlapgl guest

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    Any luck with this? I'm trying to take my '90 325is back to a stock radio and would love to have my ipod connected.

    Also, do you have any other pictures of the wiring on the back of your radio? I'm working through a mess of spliced wires. I'm specifically curious about the 3 blades and 4 wires coming out of the back. Are all the blades used?
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    Brian A

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    I have not had any luck with the 1991 318i. I believe all of the other plugs are outputs directly to the speakers. There is no seperate power amp so no line-level outputs.

    I had successfully wired in a iPod jack into my 1987 325i. The procedure is documented extensively starting on page 87 of the August 2007 Roundel (avalable online).

    If your radio is exactly the same as mine in the photos above, it's going to be tough. I opened up the case to snoop around a little, and saw a few points on the circuit boards where one might be able to hack, but it was more work than I wanted to take on for a high school commuter / track car.

    Let us know if you figure it out. I bet a lot of people would be interested (including me!!)
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    John in VA

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    MGarrison

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    Some pertinent info here: http://www.pelicanparts.com/bmw/tec...-95-CD-Changer/101-Projects-95-CD-Changer.htm

    Looks like your radio has a 13 pin plug. Apparently, this type of connection is called MBus, or M-Bus, used by both Pioneer, and Alpine, in BMW radios, at least up to a certain point in time. According to the Pelican article, the Alpine MBus setup was specific to BMW, so even if you found an Alpine 13-pin round-plug pinout, it wouldn't be accurate for BMW. That also means something like THIS isn't going to work with BMW head units; too bad... woulda been convenient, huh? However, that one might be an 8-pin Alpine MBus rather than BMW's 13 or 14 pins, which obviously wouldn't work at all.

    However, in theory, you can use the procedure outlined in the Pelican article to find which kind of radio you have. Here's an adapter cable, but it's meant to plug into the cable out of the radio at the end which terminates in the trunk. The interesting part is your head unit has 13 pins, but looks like BMW went to a 14-pin connector at the other end, and this adapter takes the 14 back to 13 to work with compatible aftermarket CD changers. Can't speak for the accuracy of the pinouts, but that might be useful for trying to figure out how to wire up some sort of ipod adapter.

    I can't find any BMW early Pioneer MBus-to-Ipod adapter, so, no luck there, at least for my search attempts.

    Looks like folks tried some other routes - one way apparently is to tie into the cassette's line feeds in the stereo, requiring a 'dead-cassette' to switch to the cassette input, allowing whatever your in-putting to play through.

    http://www.s14.net/forums/showthread.php?t=45871
    http://forums.bimmerforums.com/forum/showthread.php?t=557930

    Another option would be to retrofit a later radio - I _think_ the C33 seems to be a popular choice for aesthetics - this writeup supercedes the tape function with ipod, but he makes it think a tape is in, and toggles between tape/cd-changer, with the tape being the ipod input. Somewhere I caught a comment that if the head unit has an aux input, the leads could be soldered to that (I guess either a plug to fit ipod, or rca-jacks), and then a dead tape or tweaking the tape deck wouldn't be necessary.

    Here someone fitted a cd33 in a 5'er closer in vintage to an E30, except used a DICE adapter to allow ipod input.

    Here's a corollary thread to yours on r3vlimited; user StereoInstaller1 appears to be less than enthused about the tape-deck wiring-in (posts 18 & 25) and suggest an alternative in post 29.

    Somebody on Ebay is modding some BMW head units to have a rca jack on the front panel - http://cgi.ebay.com/ebaymotors/BMW-...700883?pt=Car_Audio_Video&hash=item483c714293

    Some additional comments about that on MyE28.com (towards the end of the post): http://www.mye28.com/viewtopic.php?t=87596; post includes links to a couple other modded radios in addition to the one listed above.

    The question would be what it takes to wire one of those into the E30, but perhaps user jjcarr there on MyE28 would share what he had to do.
    -----------------------------------------------------------------------------------

    Not directly related, but perhaps of peripheral interest:
    Alpine connector pinouts - note the two round 13-pin ones, totally different from BMW, but, also for different audio components: http://elsegra.com/Car pinouts/ALPINE.htm

    Now somebody did this & this to figure out what apparently is early 5-pin Alpine MBus... if anyone went that far with BMW's 13 pin MBus, you'd know way more about it than you could probably use.

    And last but not least, apparently people have been finding it a priority to be able to hook their laptops to their car stereo. Not sure why, but, there it is - http://car2pc.com/compatibility_full.html#bmw. If the purpose is using a laptop as a music server, given the storage capacities of flash memory these days, that seems superfluous to me, but I can see how managing and accessing music files would be a lot easier on a large, uncompromised display.

    If you get it figured out, if this is the right size (pin arrangement looks the same), the hard part would be connecting the small wires needed (at least it would for me... micro-soldering, not my forté), and it could plug right in.

    Brian, seriously dude - you need to do more googling. ;) :p
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    Brian A

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    You, Sir, are a Google search demi-god. I HAVE searched and couldn't find nothin'.

    neep3r guest

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    [IMG]
    • Member

    Brian A

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    You guys are Rock Stars.

    Now, do you have any idea what might be the control pin to use the signal from the external source? I am guessing RXEN ("Receiver Enable")??? I'd hate to apply a voltage to something that shouldn't take it.

    Thanks again for finding the diagram; it helps a lot!

    345861 guest

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    Brian, did you ever figure this out? I see the R/L outputs, you're close! I'd sacrifice the CD changer for my iPod.
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    das boots

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    +1. As a new forum member, I will gladly give up the CD changer for my IPOD......
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    Brian A

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    WARNING! LITANY OF FLAKY ALIBIS FOLLOW:

    No, I've been out of town for virtually the whole time since March. Haven't had a chance to work on it. Bought a CD pigtail from a scrapyard BMW, but turned out to be the wrong one. Car currently is in San Diego with my teen daughter. No time. etc.

    ... should be easy now that we have the pin diagram. All that is needed is a key to what the darn pins mean.
    • Member

    MGarrison

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    Guessing here, but I think you can test that pretty easily without risking much (as long as you don't short anything), if you have both a working head unit AND cd player.

    Compare the pinout neep3r put up with the 13-pin one shown at the bottom of this link I had earlier: http://www.bavtech.com/e34-guides/1995-540i-cd-changer/bmwpio-adapters.php

    Since the pinouts listed are so similar, that's a logical starting point, ya? EZ enough to test - unplug the cable from the radio, and run test wires to each corresponding pin from the radio to the plug (I'd guess the pita part is trying to get a wire to get a good connection to the pins and plug) - play a cd from the changer, and break each wire's connection one at a time with a cd playing, while trying all cd-playing functions on the head unit, and you'll know if a particular connection seems to make any difference.

    According to the bavtech pinout, if you have a pioneer 'm-bus' cd-changer, pins 7 & 9 coming out of the radio have no function (don't know about an Alpine BMW cd-changer).

    If the bavtech diagram corresponds to neep3r's, then:
    Pins:
    10 = RST (Reset)
    11 = RXN (Enable)
    12 = DATA
    13 = SCK (Clock)

    Next question, what are the functions of pins 10-13, and, more importantly, are they relevant for getting a line-level sound input into the head unit?

    If you strip a little extra insulation off one wire and swap that wire to each pin, you can more easily tap onto the wire with a voltmeter to measure the voltages, so you could start to get an idea, if the head unit needs a particular voltage signal for the cd-mode to function, what it is (assuming it's just a straigh voltage and not some modulated signal controlling a particular function).

    Without knowing more about exactly what info/data is interfaced/exchanged between the head unit and cd-changer, it gets a bit speculative; Since there's L/R channel inputs and grounds, I would guess the cd-changer does the digital-to-analog conversion and not the head unit. If that's the case, then pins 10-13 probably just control the cd-changer; stuff like possibly providing a power-on signal, play, stop, pause, ff/rew, next/previous track, track selection, cd-selection, and whatever other functions there are. I'm no electronics whiz, some electronics engineer could probably advise how to access those, decipher them, or interpret them with an oscilloscope, or whatever.

    But, if you find that switching the radio to cd-mode isn't dependent on some sort of data interface return-signal from the cd changer (ie, it will go into cd-play mode whether a changer is connected or not), then all you probably have to do is get a line-level analog signal to the channel & ground inputs, ya? If the head unit is looking for a signal from the changer, then the issue becomes what that signal is, whether it can be identified and duplicated or whatever to fool the head unit into 'thinking' a changer is connected.

    I think various ipod adapter cables can accomplish the wiring end, and I think you can google up Ipod pinouts, if that's needed. Considering that trying to get 13 tiny wires to each pin in the plug without any shorting to another is probably a hair-pulling act-in-frustration, this: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=CP-1113-ND , IF it fits, would undoubtedly make it a bit less risky, although wiring it up might be equally frustrating (let me know if you can control nano-bots :p). Anyway, until someone shows up who knows these BMW radios inside-out and can say something more definitive or to-the-contrary, I'd think you at least stand a chance of being able to get an ipod output into the head unit. Ya won't know without trying, at least, and if you're careful enough I would think you could test connections and voltages without frying the changer or head unit.

    If anyone knows why that won't work or is a bad idea, we're all ears. Offered with the caveat of course that ymmv and proceed at your own risk - short something out or get the wrong signal to something, and who knows what little piece of electronics ya might fry in the head unit or cd-changer.. _and_ that neep3r's and bavtech's pinouts, which one is for an E30 and the other for '95 540i, are a guess that they're the same, based on their similarity.
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    das boots

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    Thanks....Now I am really lost. Do not know if this can be done at all. I now noticed the rear of the E30 radios are totally different from from the C33 radios. So, evidently, the power supply and connections are not compatible. Even though a C33 can fit inside a E30 sleeve radio, they still cannot work. Not interchangeable. Another lost cause.....back to the drawing board.
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    das boots

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    A little background on doing my homework what I have researched and some more questions. I am in the process of procuring a C33 to replace the E30 stock radio head unit. I have found out that in order for the C33 to work, power adapters are required replacements. http://www.s14.net/forums/showthread.php?t=45871 Wiring Adapter Tubing/Harness 65128350192 and Antenna Adapter 65121388950. I noticed you have a recommended http://www.autosoundcentral.com/DICE_i_BMW_t_BMW_Mini_Cooper_iPod_Adapter_p/ibmwt.htm for IPOD compatiblity. I am also wondering if this http://www.ecstuning.com/BMW-E46-323Ci-M52_2.5L/ES1896860/ would also be suffice or compatible? Are both Dice be able to play the IPOD in lew of the CD changer? Thanks.
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    MGarrison

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    Hey Lawrence - best answer I can give ya is I'm not sure. Just for clarification, my first post was just sharing whatever info I could dig up, to be helpful, but I haven't tried to connect or convert a stock head unit to take an input from an ipod.

    I haven't been all that impressed with the sound quality of my old E30 & E34 radio, I just went with aftermarket units, one being a JVC, the other an Alpine. What I'd like to see that isn't out there is a din-sized head unit that both plays cd and can work with the really large capacity SDXC flash memory cards (128gb!) Expensive, but price will come down eventually and almost as much capacity as the highest capacity ipod. Downside would be in-car tune/folder access and manipulation, 'coz unlikely some head unit is going to have that as refined as ipod. But, with 128gb, don't know if I'd care - load it up with music I like, and tell the radio to play it at random, it'd be ages before I heard the same tune again!

    As for whether that particular Dice would work with.... a C33?? I don't know, you'd have to verify that, I don't know what years/models the C33 was used in, and that ECStuning link says it's for E46 323i. If the C33 was the radio in that car, you'd guess so.

    Good luck with the project though, sorry not to have specific experience to share!

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