Technic 2/4 stereo harness diagram

Gamma · 05-04-2024, 03:56 PM

2010 bmw 328i
Base stereo; no tweeters, no amp

I have recently received the technic 2/4 stereo harness and an alpine Mx-f30 4 channel amp with speaker level input harness (harness with white connector). I also have bimmertech PnP fronts and subs coming but will change those out with stock speakers once they arrive. I am trying to plan this out before going and taking out all the seats and panels. The technic harness cables are labeled as follows:

Long 4 Wire Female #1 (red,black,white,white/black)
White = LF+
White/black = LF-
Red = 12v
Black = ground

Long 4 Wire Female #2 (blue,blue/black,grey,grey/black)
Grey = RF+
Grey/black = RF-
Blue = antenna
Blue/black = not labeled (remote?)

Long 2 Wire Male #1 (red,black)
Red = not labeled
Black = not labeled

Long 2 Wire Male #2 (white,black)
White = not labeled
Black = not labeled

Short 2 Wire Female #1 (white,black)
White = not labeled
Black = not labeled

Short 2 Wire Female #2 (black,red)
Red = not labeled
Black = not labeled

On my alpine speaker level harness the white and grey wires are the LF & RF respectively. I would then wire these with the white and grey on both of the long 4 wire female cables. Beyond that I am completely stumped. I was under the impression the technic harness did not have a remote wire but there looks like one on the L4WF#2 cable so would that go to the remote on the alpine amp? Would I be connecting the S2WF’s with their L2WM counterparts?

Any advise would be great as there is little documentation on this harness from previous threads (I’ve been reading all of them) and there is no wiring diagram provided with the technic harness.

EDIT***

After some thinking on this, would it be fair to assume that I would be removing the 4 wire males from both subs, plugging in the L4WF's then running those to the trunk. I would be wiring the white and greys to the same colors on my alpine harness. Then the red 12v wire to the power on the amp, ground to ground on amp and the blue/black wire (remote?) to the remote on amp. Then I would be plugging in the L2WM's to both subs and run that to the trunk, hooking them up to my alpine harness on the green and violet wires (RL/RR)? That would just leave the 2 S2WF's that im still unsure of what they are for (maybe they are adapting aftermarket subs such as the SWS-8??)

ctuna · 05-04-2024, 05:34 PM

The OEM Stereo system is:

– OEM HU/iDrive powering front, rear and underseat woofers
– 4 channel output split into 6 speakers: front speakers connected in parallel with under seat woofers
– front outputs are full range, rear outputs are high passed
– (4) 4″ mids and (2) 6.5″ woofers. i3 woofers are 6×9″. No tweeters
– 15W x 4 (Professional Radio)/25W x 4 (iDrive) max power high level outputs

Stereo 2/4 harness is for use with an aftermarket 4-channel amp to power the front speakers and under seat woofers. Rear speakers are kept powered by the OEM HU/iDrive unit. No need to remove OEM HU/iDrive unit – Stereo 2/4 harness connects directly to the OEM woofer connectors.

The Stereo 2/4 harness requires an aftermarket 4ch amp with high level inputs and signal sensing, component speakers than can lower the built-in treble boost of the OEM signal or a DSP unit with signal sensing.

Stereo 2/4 harness is not applicable to Stereo systems with 2-wires at the woofer connector (pre 0909 production).

The Stereo 2/4 harness is designed for experienced DIYer’s and/or professional installers. Ordering of the Stereo 2/4 harness does not include installation support of any aftermarket equipment. Support is only limited to problems or/and warranty with the harness itself.

If you notice one of the amp requirements is for signal sensing. Which means no turn on lines for the amp .
Does that amp have turn on signal sensing ?

All the wires are for Inputs to the Amp and speaker only don't know how you got antenna in there.
There is no turn on wire running to the speakers. It splits the parallel connection to the door and floors when you pull out the connector.

Gamma · 05-04-2024, 05:42 PM

Quote:

Originally Posted by ctuna

The OEM Stereo system is:

– OEM HU/iDrive powering front, rear and underseat woofers
– 4 channel output split into 6 speakers: front speakers connected in parallel with under seat woofers
– front outputs are full range, rear outputs are high passed
– (4) 4″ mids and (2) 6.5″ woofers. i3 woofers are 6×9″. No tweeters
– 15W x 4 (Professional Radio)/25W x 4 (iDrive) max power high level outputs

Stereo 2/4 harness is for use with an aftermarket 4-channel amp to power the front speakers and under seat woofers. Rear speakers are kept powered by the OEM HU/iDrive unit. No need to remove OEM HU/iDrive unit – Stereo 2/4 harness connects directly to the OEM woofer connectors.

The Stereo 2/4 harness requires an aftermarket 4ch amp with high level inputs and signal sensing, component speakers than can lower the built-in treble boost of the OEM signal or a DSP unit with signal sensing.

Stereo 2/4 harness is not applicable to Stereo systems with 2-wires at the woofer connector (pre 0909 production).

The Stereo 2/4 harness is designed for experienced DIYer’s and/or professional installers. Ordering of the Stereo 2/4 harness does not include installation support of any aftermarket equipment. Support is only limited to problems or/and warranty with the harness itself.

If you notice one of the amp requirements is for signal sensing. Which means no turn on lines for the amp .
Does that amp have turn on signal sensing ?

Yes it does have signal sensing that’s why I was confused that there is a blue wire on the harness with the word antenna on it and another that is blue/black that is unlabeled (I tried peeling back the electrical tape to see if there was a label written on it further down). Going off of previous AV work, wires that have this color combo tend the be a remote wire. I was under the impression that this harness didn’t have a remote wire but I’m not sure what the wire could be for if not for remote.

Gamma · 05-04-2024, 06:03 PM

I can only assume it would hook up as follows:

Unplug 4 wire males from both subs. Attach TH L4WF’s to the BMW 4WM and run that to the trunk hooking them up as such:

L4WF:
TH white LF+ > Alpine white LF+
TH white/black LF - > Alpine white/black LF-
TH Red 12v > alpine power
TH black ground > alpine ground

L4WF:
TH grey RF+ > alpine grey RF+
TH grey/black > alpine grey/black RF+
TH blue antenna > ???
TH blue/black > ???

Then plug in the L2WM's into each sub and run to the trunk and attach to the alpine speaker harness as such:

L2WM:
TH red > alpine green RR+
TH black > alpine green/black RR-

L2WM:
TH white > alpine violet RL+
TH black > alpine violet RL -

This leaves the S2WF’s and the blue & blue/black wires that I’m unsure of

ctuna · 05-04-2024, 06:11 PM

The way I understand this works is the 4 wire connector you pulled off
the sub has both the feed to the door and one of the front high level channels
on it according to side.
Somehow he splits those I assume with the provided connector such that the High Level signal run of to the Amp and the Door speaker is somehow
connected to a longer cable that runs to the amp .
The sub should have it's own cable that plugs into the connector and runs to the amp.
This thing is all FR to the amp and two set of speaker wires that run back to
the Floors and Door respectively.
The amp should be getting the Front Right and Left channel only for Input
I assume the connector you have at the begging is from for the Amp Inputs
and came with the Amp .
Amps usually have a Way to tie the two channels per side together by switches.

Basic think is the two high level signal run into the amp (FR and FL)and two sets of speaker wire per side run
back one for the floors and one for the doors . I don't know if he combined the Input and Door speaker wires
into one cable or not.
in the setup
There is and Alpine mod pdf that has the BMW color codes.

https://www.e90post.com/forums/attac...4&d=1225483985
Don't know if this helps there where two versions 09 and before and 2010 and after.

Gamma · 05-04-2024, 06:17 PM

Quote:

Originally Posted by ctuna

The way I understand this works is the 4 wire connector you pulled off
the sub has both the feed to the door and one of the front high level channels
on it according to side.
Somehow he splits those I assume with the provided connector such that the High Level signal run of to the Amp and the Door speaker is somehow
connected to a longer cable that runs to the amp .
The sub should have it's own cable that plugs into the connector and runs to the amp.
This thing is all FR to the amp and two set of speaker wires that run back to
the Floors and Door respectively.
The amp should be getting the Front Right and Left channel only for Input
I assume the connector you have at the begging is from for the Amp Inputs
and came with the Amp .
Amps usually have a Way to tie the two channels per side together by switches.
in the setup
There is and Alpine mod pdf that has the BMW color codes.

https://www.scribd.com/document/2206...ystem-Retrofit

Yes the white connector is the alpine speaker level inputs being:

White = left front +
white/black = left front -
grey = right front +
grey/black = right front -
Green = right rear +
Green/black = right rear -
violet = left rear +
violet/black = left rear -

ctuna · 05-05-2024, 02:17 AM

You only run the FR and FL into the amp as Inputs .
Either the Amp has switches to split the channels or
you parallel connect so that both FR and FL run to
both sets of Input channels .

Read the amp manual to clarify this.

Gamma · 05-05-2024, 03:25 AM

Quote:

Originally Posted by ctuna

You only run the FR and FL into the amp as Inputs .
Either the Amp has switches to split the channels or
you parallel connect so that both FR and FL run to
both sets of Input channels .

Do you think I even need to use the 2 short females in this setup?

ctuna · 05-05-2024, 11:03 AM

Usually the Technic harnesses are labeled.
As long as you meet the electrical requirements of the circuit
you will be OK.
Which means the Fr and Fl signals of the Head unit run
to the amp inputs and a speaker signal to the underseat
and speaker signal to the doors runs from the amp to those positions.
One Input channel per side two output channels per side.
Use of Multi meter is recommended to verify connections.
Best to physically inspect the wiring and or use and ohmeter if you are uncertain
of what it does. Wires to speakers should have low ohms and to the Head unit it should be noticeably higher.
If you have the door panels off you will be able to tell what the wire is that feeds
the door speaker.

The best way to have color coded wiring diagrams is to have a copy of Ista D or the shop manual.
Ista D is the diagnostic system used by BMW during the e90 years.
Used to be easy to get on the Coding board through downloads .
Requires some setup but is like having a shop manual with guided troubleshooting.

Gamma · 05-05-2024, 11:32 AM

Quote:

Originally Posted by ctuna

Usually the Technic harnesses are labeled.
As long as you meet the electrical requirements of the circuit
you will be OK.
Which means the Fr and Fl signals of the Head unit run
to the amp inputs and a speaker signal to the underseat
and speaker signal to the doors runs from the amp to those positions.
One Input channel per side two output channels per side.

In this diagram, the purple lines are the factory wires running to the doors and subs. I’m thinking maybe the long 4 wire female (red in diagram) gets plugged into the oem 4 male and that runs to the trunk. The green wire in the diagram are the 2 wire males and that gets plugged in to the sub and ran to the trunk. I’m thinking the grey front right + & - then go to the alpine harness and the sub black and red gets plugged into the blue wires of the 4 wire female.

Gamma · 05-05-2024, 12:22 PM

I’m thinking it would look like this

Gamma · 05-05-2024, 12:31 PM

Here is what it would look like with both sides in that configuration. This would leave the rear channels alone on the alpine harness. I’m thinking this is very similar to how it’s run currently except now you have the front channels going to the alpine

ctuna · 05-05-2024, 03:11 PM

Gamma · 05-05-2024, 09:20 PM

Success!

For anyone in the future, hook up all front left/left sub positives together then all front left/left sub negatives together and Same for the right side. I used push in join connectors that have 4 wire slots and they work great.

ctuna · 05-06-2024, 01:36 AM

Something else about the Technic Harness . He has to
accommodate to different wiring's at the under seats. Pre 2009
does not have 4 wires at the sub connector the parallel
connection is made in the wiring in the door sill .
This may be the reason there is some extra connectors
in the 2/4 kit .

05-04-2024, 03:56 PM	#1
Gamma New Member 0 Rep 14 Posts Drives: 2010 E90 328i Join Date: Apr 2024 Location: Texas iTrader: (0)	Technic 2/4 stereo harness diagram 2010 bmw 328i Base stereo; no tweeters, no amp I have recently received the technic 2/4 stereo harness and an alpine Mx-f30 4 channel amp with speaker level input harness (harness with white connector). I also have bimmertech PnP fronts and subs coming but will change those out with stock speakers once they arrive. I am trying to plan this out before going and taking out all the seats and panels. The technic harness cables are labeled as follows: Long 4 Wire Female #1 (red,black,white,white/black) White = LF+ White/black = LF- Red = 12v Black = ground Long 4 Wire Female #2 (blue,blue/black,grey,grey/black) Grey = RF+ Grey/black = RF- Blue = antenna Blue/black = not labeled (remote?) Long 2 Wire Male #1 (red,black) Red = not labeled Black = not labeled Long 2 Wire Male #2 (white,black) White = not labeled Black = not labeled Short 2 Wire Female #1 (white,black) White = not labeled Black = not labeled Short 2 Wire Female #2 (black,red) Red = not labeled Black = not labeled On my alpine speaker level harness the white and grey wires are the LF & RF respectively. I would then wire these with the white and grey on both of the long 4 wire female cables. Beyond that I am completely stumped. I was under the impression the technic harness did not have a remote wire but there looks like one on the L4WF#2 cable so would that go to the remote on the alpine amp? Would I be connecting the S2WF’s with their L2WM counterparts? Any advise would be great as there is little documentation on this harness from previous threads (I’ve been reading all of them) and there is no wiring diagram provided with the technic harness. EDIT*** After some thinking on this, would it be fair to assume that I would be removing the 4 wire males from both subs, plugging in the L4WF's then running those to the trunk. I would be wiring the white and greys to the same colors on my alpine harness. Then the red 12v wire to the power on the amp, ground to ground on amp and the blue/black wire (remote?) to the remote on amp. Then I would be plugging in the L2WM's to both subs and run that to the trunk, hooking them up to my alpine harness on the green and violet wires (RL/RR)? That would just leave the 2 S2WF's that im still unsure of what they are for (maybe they are adapting aftermarket subs such as the SWS-8??) Attached Images Last edited by Gamma; 05-04-2024 at 05:32 PM..
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05-04-2024, 05:34 PM	#2
ctuna Lieutenant General 1921 Rep 13,124 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	The OEM Stereo system is: – OEM HU/iDrive powering front, rear and underseat woofers – 4 channel output split into 6 speakers: front speakers connected in parallel with under seat woofers – front outputs are full range, rear outputs are high passed – (4) 4″ mids and (2) 6.5″ woofers. i3 woofers are 6×9″. No tweeters – 15W x 4 (Professional Radio)/25W x 4 (iDrive) max power high level outputs Stereo 2/4 harness is for use with an aftermarket 4-channel amp to power the front speakers and under seat woofers. Rear speakers are kept powered by the OEM HU/iDrive unit. No need to remove OEM HU/iDrive unit – Stereo 2/4 harness connects directly to the OEM woofer connectors. The Stereo 2/4 harness requires an aftermarket 4ch amp with high level inputs and signal sensing, component speakers than can lower the built-in treble boost of the OEM signal or a DSP unit with signal sensing. Stereo 2/4 harness is not applicable to Stereo systems with 2-wires at the woofer connector (pre 0909 production). The Stereo 2/4 harness is designed for experienced DIYer’s and/or professional installers. Ordering of the Stereo 2/4 harness does not include installation support of any aftermarket equipment. Support is only limited to problems or/and warranty with the harness itself. If you notice one of the amp requirements is for signal sensing. Which means no turn on lines for the amp . Does that amp have turn on signal sensing ? All the wires are for Inputs to the Amp and speaker only don't know how you got antenna in there. There is no turn on wire running to the speakers. It splits the parallel connection to the door and floors when you pull out the connector. Last edited by ctuna; 05-04-2024 at 05:50 PM..
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05-04-2024, 06:03 PM	#4
Gamma New Member 0 Rep 14 Posts Drives: 2010 E90 328i Join Date: Apr 2024 Location: Texas iTrader: (0)	I can only assume it would hook up as follows: Unplug 4 wire males from both subs. Attach TH L4WF’s to the BMW 4WM and run that to the trunk hooking them up as such: L4WF: TH white LF+ > Alpine white LF+ TH white/black LF - > Alpine white/black LF- TH Red 12v > alpine power TH black ground > alpine ground L4WF: TH grey RF+ > alpine grey RF+ TH grey/black > alpine grey/black RF+ TH blue antenna > ??? TH blue/black > ??? Then plug in the L2WM's into each sub and run to the trunk and attach to the alpine speaker harness as such: L2WM: TH red > alpine green RR+ TH black > alpine green/black RR- L2WM: TH white > alpine violet RL+ TH black > alpine violet RL - This leaves the S2WF’s and the blue & blue/black wires that I’m unsure of
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05-04-2024, 06:11 PM	#5
ctuna Lieutenant General 1921 Rep 13,124 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	The way I understand this works is the 4 wire connector you pulled off the sub has both the feed to the door and one of the front high level channels on it according to side. Somehow he splits those I assume with the provided connector such that the High Level signal run of to the Amp and the Door speaker is somehow connected to a longer cable that runs to the amp . The sub should have it's own cable that plugs into the connector and runs to the amp. This thing is all FR to the amp and two set of speaker wires that run back to the Floors and Door respectively. The amp should be getting the Front Right and Left channel only for Input I assume the connector you have at the begging is from for the Amp Inputs and came with the Amp . Amps usually have a Way to tie the two channels per side together by switches. Basic think is the two high level signal run into the amp (FR and FL)and two sets of speaker wire per side run back one for the floors and one for the doors . I don't know if he combined the Input and Door speaker wires into one cable or not. in the setup There is and Alpine mod pdf that has the BMW color codes. https://www.e90post.com/forums/attac...4&d=1225483985 Don't know if this helps there where two versions 09 and before and 2010 and after. Last edited by ctuna; 05-04-2024 at 06:28 PM..
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05-05-2024, 02:17 AM	#7
ctuna Lieutenant General 1921 Rep 13,124 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	You only run the FR and FL into the amp as Inputs . Either the Amp has switches to split the channels or you parallel connect so that both FR and FL run to both sets of Input channels . Read the amp manual to clarify this.
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05-05-2024, 11:03 AM	#9
ctuna Lieutenant General 1921 Rep 13,124 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	Usually the Technic harnesses are labeled. As long as you meet the electrical requirements of the circuit you will be OK. Which means the Fr and Fl signals of the Head unit run to the amp inputs and a speaker signal to the underseat and speaker signal to the doors runs from the amp to those positions. One Input channel per side two output channels per side. Use of Multi meter is recommended to verify connections. Best to physically inspect the wiring and or use and ohmeter if you are uncertain of what it does. Wires to speakers should have low ohms and to the Head unit it should be noticeably higher. If you have the door panels off you will be able to tell what the wire is that feeds the door speaker. The best way to have color coded wiring diagrams is to have a copy of Ista D or the shop manual. Ista D is the diagnostic system used by BMW during the e90 years. Used to be easy to get on the Coding board through downloads . Requires some setup but is like having a shop manual with guided troubleshooting. Last edited by ctuna; 05-05-2024 at 11:14 AM..
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05-05-2024, 12:22 PM	#11
Gamma New Member 0 Rep 14 Posts Drives: 2010 E90 328i Join Date: Apr 2024 Location: Texas iTrader: (0)	I’m thinking it would look like this Attached Images
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05-05-2024, 12:31 PM	#12
Gamma New Member 0 Rep 14 Posts Drives: 2010 E90 328i Join Date: Apr 2024 Location: Texas iTrader: (0)	Here is what it would look like with both sides in that configuration. This would leave the rear channels alone on the alpine harness. I’m thinking this is very similar to how it’s run currently except now you have the front channels going to the alpine Attached Images
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05-05-2024, 03:11 PM	#13
ctuna Lieutenant General 1921 Rep 13,124 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	FYI Base System Upgrades http://www.e90post.com/forums/showthread.php?t=445266 http://www.monsteraudiodesign.co.uk/ http://www.1addicts.com/forums/showthread.php?t=634957 http://f30.bimmerpost.com/forums/sho....php?t=1003810 http://www.e90post.com/forums/showthread.php?t=822366 http://www.e90post.com/forums/showth...1#post16679904 http://www.e90post.com/forums/showthread.php?t=581379 http://www.e90post.com/forums/showthread.php?t=451941 http://www.e90post.com/forums/showthread.php?t=540954 http://www.e90post.com/forums/showth...ghlight=Dotech http://www.e90post.com/forums/showthread.php?t=495855 http://www.e90post.com/forums/showthread.php?t=494299 http://www.diymobileaudio.com/forum....morel-jbl.html http://www.e90post.com/forums/showth...1#post16679904 http://www.e90post.com/forums/showth...ht=amp+upgrade http://www.bimmerfest.com/forums/sho...d.php?t=550771
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05-05-2024, 09:20 PM	#14
Gamma New Member 0 Rep 14 Posts Drives: 2010 E90 328i Join Date: Apr 2024 Location: Texas iTrader: (0)	Success! For anyone in the future, hook up all front left/left sub positives together then all front left/left sub negatives together and Same for the right side. I used push in join connectors that have 4 wire slots and they work great.
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05-06-2024, 01:36 AM	#15
ctuna Lieutenant General 1921 Rep 13,124 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	Something else about the Technic Harness . He has to accommodate to different wiring's at the under seats. Pre 2009 does not have 4 wires at the sub connector the parallel connection is made in the wiring in the door sill . This may be the reason there is some extra connectors in the 2/4 kit .
	Appreciate 0 Quote