Removing Interior Wires

[Phloozy]

I am getting my car gutted and ready for a cage in the off season and want to start tackling the interior wiring harnesses. I am going to be removing all the speakers and airbags so I would like to remove all the wires along with them. This is my first time doing something like this and I am scared I might remove something important.

Has anyone done this before and have any tips? Is there anything I should make sure I dont remove that isnt obvious?

[fe1rx]

Originally Posted by Phloozy

I am getting my car gutted and ready for a cage in the off season and want to start tackling the interior wiring harnesses. I am going to be removing all the speakers and airbags so I would like to remove all the wires along with them. This is my first time doing something like this and I am scared I might remove something important.

Has anyone done this before and have any tips? Is there anything I should make sure I dont remove that isnt obvious?

There is a lot that can go wrong when you start removing wires. There is a lot of interconnectedness in our cars that is not self apparent. At the very least, get a complete set of wiring diagrams and make sure you fully understand them before you remove any wire. You can get wiring diagrams from the manual described in this post:

https://www.1addicts.com/forums/show...0&postcount=69

Wiring diagrams from generic sources like this can only be trusted 95%, and your actual installed options make a difference in which diagram applies (which is not always self-apparent). But they are a very good start.

I have done a bit of what you are proposing as part of my dash logger installation. A relevant excerpt from that thread:

"While I was at it I elected to remove the existing MOST bus, USB interface, and wiring provisions for Sat radio, digital tuner, remote CD changer, exhaust flap and unused shark fin coax. My car had the iPhone integration option, which brought with it all those wiring provisions. I would not have attacked the removal without a wiring diagram in hand as there is significant risk of removing something significant and unintended when stripping wiring. As it is, my radio still works after the stripping out, so all is good. Fun fact, fuse 74 is identified on the fuse map as for the exhaust flap only. Actually, it also powers the gauge cluster, so after stripping out the exhaust flap solenoid and associated wiring, that fuse still has to stay. For reasons perhaps best explained by OCD I want to remove stuff that is not strictly necessary, without giving rise to un-extinguishable warning lights. Threading that needle takes some care."

While it is tempting to strip out wires completely back to their source, in some cases this will not be practical and you will have to leave a capped wire in place. Leaving unused energized wires should be avoided, even if capped. If you are able, remove the associated fuse and call the circuit dead. Identifying the wire with a fuse number is a good idea in case you ever need to add a circuit and want to re-energize it (or later get better access and want to strip it out completely).

Working on one circuit at a time and checking essential functions along the way is a good idea to avoid making a serious mistake that is very difficult to track down. Coding out things as they are removed, and confirming that no codes are thrown is a good idea to keep the logic tidy.

There is a lot said for removing boxes, but not wires, although I suspect your ODC (like mine) won't let you do that.

Do not disable your ABS. Our cars need functioning ABS for proper function of electronic brake force distribution. Without it, threshold braking will suffer.

Unless you are electronically literate, you can very easily screw things up ...

[Phloozy]

Originally Posted by fe1rx

There is a lot that can go wrong when you start removing wires. There is a lot of interconnectedness in our cars that is not self apparent. At the very least, get a complete set of wiring diagrams and make sure you fully understand them before you remove any wire. You can get wiring diagrams from the manual described in this post:

https://www.1addicts.com/forums/show...0&postcount=69

Wiring diagrams from generic sources like this can only be trusted 95%, and your actual installed options make a difference in which diagram applies (which is not always self-apparent). But they are a very good start.

I have done a bit of what you are proposing as part of my dash logger installation. A relevant excerpt from that thread:

"While I was at it I elected to remove the existing MOST bus, USB interface, and wiring provisions for Sat radio, digital tuner, remote CD changer, exhaust flap and unused shark fin coax. My car had the iPhone integration option, which brought with it all those wiring provisions. I would not have attacked the removal without a wiring diagram in hand as there is significant risk of removing something significant and unintended when stripping wiring. As it is, my radio still works after the stripping out, so all is good. Fun fact, fuse 74 is identified on the fuse map as for the exhaust flap only. Actually, it also powers the gauge cluster, so after stripping out the exhaust flap solenoid and associated wiring, that fuse still has to stay. For reasons perhaps best explained by OCD I want to remove stuff that is not strictly necessary, without giving rise to un-extinguishable warning lights. Threading that needle takes some care."

While it is tempting to strip out wires completely back to their source, in some cases this will not be practical and you will have to leave a capped wire in place. Leaving unused energized wires should be avoided, even if capped. If you are able, remove the associated fuse and call the circuit dead. Identifying the wire with a fuse number is a good idea in case you ever need to add a circuit and want to re-energize it (or later get better access and want to strip it out completely).

Working on one circuit at a time and checking essential functions along the way is a good idea to avoid making a serious mistake that is very difficult to track down. Coding out things as they are removed, and confirming that no codes are thrown is a good idea to keep the logic tidy.

There is a lot said for removing boxes, but not wires, although I suspect your ODC (like mine) won't let you do that.

Do not disable your ABS. Our cars need functioning ABS for proper function of electronic brake force distribution. Without it, threshold braking will suffer.

Unless you are electronically literate, you can very easily screw things up ...

I was hoping you would chime in and this is very helpful. I am going to take it as slow as possible and only remove wires when I am sure I know what each one does. I definitely dont want to disable to ABS which was one of the things I was worried I would mess up when trying to take out other wires. Thanks for the detailed response.

[tsk94]

Watch out for the PTCAN wires - should be on the passenger side in the main loom. Otherwise, removing the wiring from radio/speakers and airbags are pretty safe and straight forward. Like fe1rx mentioned, get some sort of wiring diagram for the car as that will help.

Just take your time and label wires you've cut.

[Phloozy]

I can completely remove the MOST BUS if I have taken out my headunit correct? Any functionality im missing that I should keep it for? Same goes for the Airbag control unit and all of the wires going to it in the center console?

[amg6975]

I have done this. All audio, airbag, and even all the roof wiring can be removed, it will take some coding but you can get rid of most errors in most modules. If you have an auto/DCT it will throw an error for not seeing the seat belt buckles, and the DME will throw an error for not being able to see the explosive battery disconnect.

I removed better than 40lbs of wire from my car...

Al Fe1rx says there are some things that have connections in the harness that you'll need to work around, all the LED lighting is driven from a single NFRM pin, there's three CAN busses that have junctions in the harness, there's the WKUP from the CAS, there are grounds, etc. Every one of these that I had to cut/change I actually cut out the unused wires and then reterminated each junction so there were no snags. Remember, the harness will vibrate so anything pointy or sharp in the harness will eventually short to something.

Yes, you can remove the MOST bus, even if you leave the head unit you can code it off so the HU doesn't look for it.

It is a lot of work to unwrap the whole harness, thin it out, then rewrap it but 40-50lbs is a lot of weight when you've removed everything else.

[Phloozy]

Originally Posted by amg6975

I have done this. All audio, airbag, and even all the roof wiring can be removed, it will take some coding but you can get rid of most errors in most modules. If you have an auto/DCT it will throw an error for not seeing the seat belt buckles, and the DME will throw an error for not being able to see the explosive battery disconnect.

I removed better than 40lbs of wire from my car...

Al Fe1rx says there are some things that have connections in the harness that you'll need to work around, all the LED lighting is driven from a single NFRM pin, there's three CAN busses that have junctions in the harness, there's the WKUP from the CAS, there are grounds, etc. Every one of these that I had to cut/change I actually cut out the unused wires and then reterminated each junction so there were no snags. Remember, the harness will vibrate so anything pointy or sharp in the harness will eventually short to something.

Yes, you can remove the MOST bus, even if you leave the head unit you can code it off so the HU doesn't look for it.

It is a lot of work to unwrap the whole harness, thin it out, then rewrap it but 40-50lbs is a lot of weight when you've removed everything else.

This is AMAZING. When you coming over to do this :P I am hoping to take it slow and remove things 1 by 1 as I feel confident. I am trying to keep cutting down to a minimum as this is a first for me so I would need to be 100% positive before I do anything like that.

[Phloozy]

Originally Posted by amg6975

I have done this. All audio, airbag, and even all the roof wiring can be removed, it will take some coding but you can get rid of most errors in most modules. If you have an auto/DCT it will throw an error for not seeing the seat belt buckles, and the DME will throw an error for not being able to see the explosive battery disconnect.

I removed better than 40lbs of wire from my car...

Al Fe1rx says there are some things that have connections in the harness that you'll need to work around, all the LED lighting is driven from a single NFRM pin, there's three CAN busses that have junctions in the harness, there's the WKUP from the CAS, there are grounds, etc. Every one of these that I had to cut/change I actually cut out the unused wires and then reterminated each junction so there were no snags. Remember, the harness will vibrate so anything pointy or sharp in the harness will eventually short to something.

Yes, you can remove the MOST bus, even if you leave the head unit you can code it off so the HU doesn't look for it.

It is a lot of work to unwrap the whole harness, thin it out, then rewrap it but 40-50lbs is a lot of weight when you've removed everything else.

What do you mean by junction in the harness? For example if I want to remove the airbag module in the center console as well as the wires, I found this in the diagram. It says there are 2 "SIG CAN BUS" wires. Are you saying I would need to keep the harness with those 2 wires connected or am I way off base?

[Phloozy]

Small update for anyone starting this with the Hi-Fi radio, the amp is not in the trunk......I was trying to follow wires and couldnt figure out where the amp was or where they were going, everyone online said the trunk... The Hi-Fi amp is under the metal cap on the driver side of the rear seat area. I know it's pretty obvious when you see all the wires going there but I am trying to be super careful. Amp is now out, weighs 5lbs.

[amg6975]

Originally Posted by Phloozy

What do you mean by junction in the harness? For example if I want to remove the airbag module in the center console as well as the wires, I found this in the diagram. It says there are 2 "SIG CAN BUS" wires. Are you saying I would need to keep the harness with those 2 wires connected or am I way off base?

If you trace those CAN lines back through the harness you'll find they land at two (one for each signal) crimp/heatshrink connections just behind where the blower motor is. All three major CAN busses have junctions on the passenger and driver side of the harness that are all wrapped up. The "right" way to eliminate those CAN lines is to unwrap the harness, trace back to those two junctions and remove them there. Attached is a picture I found of one, this was for a few sensor power items, not CAN but you get the idea.

Originally Posted by Phloozy

Small update for anyone starting this with the Hi-Fi radio, the amp is not in the trunk......I was trying to follow wires and couldnt figure out where the amp was or where they were going, everyone online said the trunk... The Hi-Fi amp is under the metal cap on the driver side of the rear seat area. I know it's pretty obvious when you see all the wires going there but I am trying to be super careful. Amp is now out, weighs 5lbs.

In my 2012 the HiFi amp was in the left side trunk side compartment.

[Phloozy]

Originally Posted by amg6975

If you trace those CAN lines back through the harness you'll find they land at two (one for each signal) crimp/heatshrink connections just behind where the blower motor is. All three major CAN busses have junctions on the passenger and driver side of the harness that are all wrapped up. The "right" way to eliminate those CAN lines is to unwrap the harness, trace back to those two junctions and remove them there. Attached is a picture I found of one, this was for a few sensor power items, not CAN but you get the idea.



In my 2012 the HiFi amp was in the left side trunk side compartment.

Ok so I think I get it now. What you are saying is the wires can be removed but instead of following them all the way back, follow them until you get to where they merge, take it apart there, remove the unneeded wire and leave the others connected, rewrap it? I have not taken the heater code out yet, will these be impossible to get without doing that first?

Also as for the amp I think its because I have the harman kardon which I figured was the same as the HiFi. It was located behind this metal shield.

[amg6975]

Originally Posted by Phloozy

Ok so I think I get it now. What you are saying is the wires can be removed but instead of following them all the way back, follow them until you get to where they merge, take it apart there, remove the unneeded wire and leave the others connected, rewrap it? I have not taken the heater code out yet, will these be impossible to get without doing that first?

Basically, yeah. Just don't leave any cut wires in the harness, big shorting potential there.

Yeah, to do it how I did you'll need to remove the whole dash and dash support and HVAC unit.

[Tautvydas200]

Hello, I'm making track car and planning to remove cas, abs, DME, airbag, radio modules. Car will be with m54 engine. Has anyone tried to make heating, instrument cluster and lights working?

[amg6975]

Originally Posted by Tautvydas200

Hello, I'm making track car and planning to remove cas, abs, DME, airbag, radio modules. Car will be with m54 engine. Has anyone tried to make heating, instrument cluster and lights working?

M54? good luck... very different electronics platform than the E8x and E9x. Removing the CAS will be quite problematic as almost everything in the car relies on it.

[mindspin311]

Originally Posted by Tautvydas200

Hello, I'm making track car and planning to remove cas, abs, DME, airbag, radio modules. Car will be with m54 engine. Has anyone tried to make heating, instrument cluster and lights working?

Why are you removing ABS? And don't feed me some bullshit about how racecars don't have ABS.

[Tautvydas200]

Because I don't need abs in rally car, for better stopping distance. So I'm already removed every unused wire from the car. Also removed abs, DME, airbags and other unused modules. Unfortunately CAS can't be removed because it sends wake up signal through can bus to instrument cluster and heating control module. Also inserted wires for M54 engine, cut off switch and other stuff needed for rally and rewraped everything in split tube.

[gixracer]

i guess I'm a little late to this game. The audio harness separates on its own. at far as removing the airbag stuff I had to leave in the b-pillar sensors and wiring to keep the airbag and belt lights off on the dash. I left in the hvac blower and heater core incase it got steamy on the windows. Dont understand why the abs delete, it will save your ass and let you know when you get to crazy on the brakes. Currently have a n55 swapped 128 shell with 4-point cage for track duty.

[amg6975]

Originally Posted by gixracer

at far as removing the airbag stuff I had to leave in the b-pillar sensors and wiring to keep the airbag and belt lights off on the dash.

There's a pretty specific order of operations here: Clear ABG faults with everything hooked up, code KOMBI to not look for the ABG module, then remove the ABG module, then remove all the sensors.

My car has no ABG module or any of the wiring associated with it, and none of the impact sensors and it's perfectly happy.

You may be able to clear errors from the KOMBI if the module is already removed, but this is what worked for me.

Edit: KOMBI coding parameters for post completeness:

SFY_ALIVE_ZAEHLER nicht_aktiv
SFY_ID_MONITOR nicht_aktiv