Announcement

Collapse
No announcement yet.

Radio Wiring and Amp Bypass

Collapse
This is a sticky topic.
X
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • bradnic
    replied
    Originally posted by Aleman View Post
    Found out what the two mystery wires go to. Nothing in the E30.

    https://www.r3vlimited.com/board/sho...69&postcount=6
    yes they were for a 'dot matrix' feature. lots of speculation, but the post you linked to was probably close - just a way to display radio or cd track number info somewhere else, probably on the 5 series as mentioned. I've never seen evidence of such a feature back then, but it was certainly common in the early to mid 2000 timeframe.

    Leave a comment:


  • Aleman
    replied
    Originally posted by Andrew325is View Post
    I posted this in another thread I made, but maybe it makes more sense to post it here.

    Does anyone know the best way to do the amp bypass mod while leaving the original wiring intact? I know, needlessly complicated, but I don't want to modify the original wiring so I can revert back to stock without having to re-wire anything later.

    I have an amp that isn't good I'm going to attempt to use for this. The issue I've come across are the common ground speaker wires coming from the radio (this is a 90 325is with premium sound); the 2 yellow/brown and 2 blue/brown wires that combine into the single brown/black wire just before the amp connector. I read there shouldn't be common grounds for the speakers for the aftermarket HU (should be floating ground instead). So do I just connect the positive wires together inside the amp and leave the grounds connected as they are in the amp? Does the amp need to be powered on for the grounds to do whatever they need to do or should I terminate the power and remote turn on wires?

    I used my multimeter to test the grounds at the amp connector for continuity and they don't have continuity. They go through circuitry in the amp, and I don't know exactly how the circuitry is configured and what it consists of or what it does exactly.

    Maybe I should just install a floating ground adapter inside the amp.
    One way to do it is to use a ton of Tap Splice Connectors. You can pull the amp out, and then bridge from speaker loom to radio loom with one of these splice connectors on each wire. No cutting.

    Last edited by Aleman; 05-13-2019, 06:33 AM.

    Leave a comment:


  • Aleman
    replied
    Found out what the two mystery wires go to. Nothing in the E30.

    https://www.r3vlimited.com/board/sho...69&postcount=6

    Leave a comment:


  • Aleman
    replied
    I checked all the wiring diagrams and none of them covers the cm5908. Anyone know what the blue/gray and white/brown wires hardwired from the HU should connect to? Those colors aren't on the 89 wiring diagrams.

    Also, does the yellow/brown HU wire connect to a solid brown wire? And the blue/brown HU wire connect to a solid brown wire? The 89 diagrams only show the yellow HU wire connecting to yellow/red amp wire and blue HU wire connecting to blue/red amp wire.

    I see the yellow HU wire connects to the yellow/bk and the blue HU wire to the blue/bk. Once I get it hooked up and working I'll post a clear chart for the next guy.

    Sent from my smart phone using Tapatalk
    Last edited by Aleman; 05-08-2019, 05:51 PM.

    Leave a comment:


  • bradnic
    replied
    Originally posted by Aleman View Post
    @bradnic
    How do you know if your amp is fried? Symptoms?
    -squealing in one or more speakers
    -distortion from the speakers at less than full volume
    -low static noise from one of more speakers even when nothing is playing in the headunit
    and of course
    -no sound

    Unfortunately to be 100% sure it's the amp and not the radio, you need to do the amp bypass or swap the headunit out. So it's not uncommon to fix a radio and then later find the premium amp needs service too
    Last edited by bradnic; 04-28-2019, 03:24 PM.

    Leave a comment:


  • Aleman
    replied
    @bradnic
    THANKS! That clears up a lot of the mystery.
    How do you know if your amp is fried? Symptoms?

    Sent from my smart phone using Tapatalk

    Leave a comment:


  • bradnic
    replied
    Originally posted by Andrew325is View Post
    I posted this in another thread I made, but maybe it makes more sense to post it here.

    Does anyone know the best way to do the amp bypass mod while leaving the original wiring intact? I know, needlessly complicated, but I don't want to modify the original wiring so I can revert back to stock without having to re-wire anything later.

    I have an amp that isn't good I'm going to attempt to use for this. The issue I've come across are the common ground speaker wires coming from the radio (this is a 90 325is with premium sound); the 2 yellow/brown and 2 blue/brown wires that combine into the single brown/black wire just before the amp connector. I read there shouldn't be common grounds for the speakers for the aftermarket HU (should be floating ground instead). So do I just connect the positive wires together inside the amp and leave the grounds connected as they are in the amp? Does the amp need to be powered on for the grounds to do whatever they need to do or should I terminate the power and remote turn on wires?

    I used my multimeter to test the grounds at the amp connector for continuity and they don't have continuity. They go through circuitry in the amp, and I don't know exactly how the circuitry is configured and what it consists of or what it does exactly.

    Maybe I should just install a floating ground adapter inside the amp.
    You ever get an answer to this?
    I did the amp bypass under the rear seat of my 90 vert. I then reversed it after refurbishing my power amp. I'm working on a harness bypass for aftermarket amps that doesn't require cutting the OEM wiring, but it will be a while.

    If you're asking about getting rid of the common ground extensions at either end so you can run an aftermarket headhunt, right now you're stuck needing to mod the wiring. There actually is a 2 to 4 channel adapter from BMW that DOES preserve the individual speaker grounds. It's expensive though, and still has the German speaker connectors on it.
    Last edited by bradnic; 04-28-2019, 12:53 PM.

    Leave a comment:


  • bradnic
    replied
    So @Aleman you have the 4 channel common ground setup common to the later cars. basically at the head unit all the speaker grounds are terminated on those 2 brown wires that get screwed on to the back of the radio heatsink.

    Radios like the CM5908 and KE83ZBM have 4 amp channels (and a CD changer connector). the earlier radios like the CM5905, CM5907 and KE81ZBM only have 2 amp channels.

    You have probably seen pics with early model E30s showing an external fader knob. That fader was how a 2 channel radio drove 4 sets of speakers in the early model cars.

    The left side of the big black connector in your wiring is what the old external fader used to plug into. In common ground 4 channel cars like yours the headhunt wiring included a 2 to 4 channel adapter harness that replaced the fader. The right side of that black connector is one end of the adapter. the other end is a rectangular connector with 4 blades labeled LH (links hinted = left rear) and RH (rechts hinten = right rear). Those are the rear head unit speaker connections.

    Here is a standalone picture of the 2 to 4 channel adapter, part number 61101388934


    Note that there are no ground wires in that harness - on either end. You can tell what the head unit output wires do from the color coding:
    blue head unit wires are for the right channels
    yellow head unit wires are for the left channels
    blue or yellow red striped wires are for the front channels
    blue or yellow black striped wires are for the right channels

    Now regarding the BMW Sound System wiring, those head unit speaker outputs get routed to your blaupunkt trunk amp harness. It's about 90% certain the amp is fried. You can either (1) rebuild it, (2) bypass it and run headunit only or (3) bypass it and replace with an aftermarket 4 or 5 channel amp. @Rontgen's pic beautifully captures the bypass you need to do for case 2. For case 3 you route the yellow and blue wire pairs to the aftermarket amp's speaker level inputs, and the aftermarket amp's outputs get wired to the black and grey striped wires that go to the four speaker sets.

    Here are the power amp output wiring colors (probably posted for the 135th time lol)
    grey amp wires are for the front speakers
    black amp wires are for the rear speakers
    grey or black wires with red stripes are left channel
    grey or black wires with violet / purple stripes are left channel ground
    grey or black wires with white stripes are right channel
    grey or black wires with brown stripes are right channel ground


    the three remaining power amp wires are self explanatory, red for battery, white for amp on/off and brown for ground.

    FYI I'm working on an adapter harness for all this so no wire cutting is needed, but will be a while. First install will be Cosmo, my 86 Cosmoblau 325. It will be running an Infinity REF 4555A 5 channel amp and a JBL 1224SS trunk sub.

    for completeness, here's a 1986 BMW Sound System schematic for TWO CHANNEL RADIOS showing the wiring for the radio, amp, speakers and power antenna. Note the radio output wiring is common ground.


    Here's the same set of schematics for a 1989 late production BMW sound system car with FOUR CHANNEL RADIO wiring. Again the radio output wiring to the power amp is a common ground setup.

    Finally, here's an 1989 4 CHANNEL RADIO ONLY late production schematic. Note each speaker has it's own ground wire. Early production is electrically the same with some harness connector differences


    NOTE The 1989 325i / 325is electrical troubleshooting manual has 4 different radio + amp schematics based on early vs late production, radio only vs BMW Sound system. Make sure you're looking at the right version for your car!
    -- 2 channel (up to early 88 or so) or 4 channel radio
    -- radio only, or BMW Sound System with amp
    -- coupe/sedan or convertible. Convertibles with BMW Sound System do not have rear tweeters, or crossovers on the rear speakers.
    Last edited by bradnic; 04-28-2019, 03:38 PM.

    Leave a comment:


  • Aleman
    replied
    How do I wire my CM5908 WITH the amp? On the wiring diagram for a 1989 with amp, it shows only one wire per speaker from the HU to the amp, rather than 2 (just like rontgen explains above). I think I can figure it out by trial and error as far as which of the two wires from the radio I should use per speaker. My big question is around what I see in the factory wiring. There's a harness connected to the speaker harness that looks factory given all the German language and BMW logos, but it looks like something really strange is going on there. 8 speaker wires in, 2 out. I hesitate to cut any harness, so have you guys ever seen this setup in a late model E30 with premium sound? 1990. Maybe my car had something other than a CM5908?

    Thanks for any info you may share.

    Sent from my smart phone using Tapatalk
    Last edited by Aleman; 04-27-2019, 12:34 PM.

    Leave a comment:


  • Andrew325is
    replied
    I posted this in another thread I made, but maybe it makes more sense to post it here.

    Does anyone know the best way to do the amp bypass mod while leaving the original wiring intact? I know, needlessly complicated, but I don't want to modify the original wiring so I can revert back to stock without having to re-wire anything later.

    I have an amp that isn't good I'm going to attempt to use for this. The issue I've come across are the common ground speaker wires coming from the radio (this is a 90 325is with premium sound); the 2 yellow/brown and 2 blue/brown wires that combine into the single brown/black wire just before the amp connector. I read there shouldn't be common grounds for the speakers for the aftermarket HU (should be floating ground instead). So do I just connect the positive wires together inside the amp and leave the grounds connected as they are in the amp? Does the amp need to be powered on for the grounds to do whatever they need to do or should I terminate the power and remote turn on wires?

    I used my multimeter to test the grounds at the amp connector for continuity and they don't have continuity. They go through circuitry in the amp, and I don't know exactly how the circuitry is configured and what it consists of or what it does exactly.

    Maybe I should just install a floating ground adapter inside the amp.
    Last edited by Andrew325is; 02-21-2019, 12:16 PM.

    Leave a comment:


  • Rontgen
    replied
    Did this re-wire tonight on my sonís 90 325is. The car has premium sound with no fader dial in the dash. Very bizarre wiring for what should be a very simple audio circuit.

    From amp to speakers is a piece of cake and Lukeís original post is spot on. 4 speakers, 4 twisted pairs, 8 wires total. Easy.

    The connection from the front of the car to the amp input is where things get confusing. Rather than sending 8 wires from the radio to the amp like any sane person would do, BMW opted to tie all the grounds together at both ends. Lucky for us, the twisted pairs still exist, you just have to untape the harness and work your way back until you find them. Keep in mind that the ground colors in the first post may not match your car. Youíll probably end up with 2 yellow/brown wires and 2 blue/brown. Just keep the twisted pairs together and connect one at a time.

    Picture of our trunk wiring before we taped it all up with cloth harness tape. Hope this helps!

    Leave a comment:


  • HEIS83
    replied
    no amp in the trunk. right now i am waiting on the headunit to be returned so I can hook back up and troubleshoot again. I want to avoid having to re-wire the speakers but I am running out of possible solutions.

    Leave a comment:


  • george graves
    replied
    So, this might help a bit. But some amps don't play nicely with shared grounds - or different ground on the speakers vs the amp/deck. And the "factory fader" can be a know problem. But as you said, it was cut out, but perhaps the wiring was the issue? It's too early in the AM for me to think ;) Hope that bit of trivia helps!

    Leave a comment:


  • HEIS83
    replied
    Originally posted by george graves View Post
    Stock amp is on the driver's side of the trunk, on the back side of the wheel wel, under a carpeted panel. Did your car had a "fader" in the dash?
    Yes there is a fader in the dash, but PO had an aftermarket stereo and the fader wires had been cut. What is strange is that the new speakers/head unit worked great for a few months and then crapped out randomly one day. ill double check the trunk again tonight and see if I can track the amp down.

    In researching I didn't find any fuses that would be related to it and if one was and it went, then the whole stereo would go.

    Leave a comment:


  • george graves
    replied
    Stock amp is on the driver's side of the trunk, on the back side of the wheel wel, under a carpeted panel. Did your car had a "fader" in the dash?

    Leave a comment:

Working...
X