Page 1 of 2 12 LastLast
Results 1 to 25 of 36

Thread: LS1-E36 A/C Wiring

  1. #1
    Join Date
    May 2011
    Location
    Memphis
    Posts
    211
    My Cars
    10 535i, 97 M3, 69 1602

    LS1-E36 A/C Wiring

    So ive pulled the motor out of my car for some upgrades/goodies, one of which being A/C.

    Now trying to find out what to wire up to make A/C work with the stock bmw lines and GM Compressor. So far the info is spread out and difficult to understand from what I can tell. So the info I need is ...

    What Parts do I need to buy? sensors/ switches etc

    What wires from the GM PCM do I wire into what wire from the x20 or otherwise?

    Anything else that I will need?

    I plan on doing a detailed writeup with pics as I go along if I can sort it out!

    Thanks

  2. #2
    Join Date
    Mar 2011
    Location
    Dallas, TX
    Posts
    764
    My Cars
    2008 535i
    You need the GM pressure switch and the corresponding fitting that you will need to weld / braze onto your AC line. Plus hook up the AC request signal from X20 Pin6 to Red PCM Pin 17 or C230 - F

    Pressure switch - ACDELCO Part # 155742
    Special port - Docs Blocks - AC0146

    You will need a reversal relay on the AC request output or your AC button will work backwards. On when off and vice versa.

    You will also need to use a relay to engage the AC clutch.
    Last edited by Kaane; 03-26-2012 at 01:25 AM.

  3. #3
    Join Date
    Mar 2006
    Location
    Memphis, TN
    Posts
    2,471
    My Cars
    95 M3, 01 330ci
    There is a huge FAQ thread that tells you step by step how to do it in the sticky



    http://forums.bimmerforums.com/forum...d.php?t=723277

    Also braaps thread has the wiring info. The wiring info I gave you originally has the information in it as well.
    Last edited by Pzary3233; 03-26-2012 at 10:00 AM. Reason: Automerged Doublepost

  4. #4
    Join Date
    May 2011
    Location
    Memphis
    Posts
    211
    My Cars
    10 535i, 97 M3, 69 1602
    Quote Originally Posted by Kaane View Post
    You need the GM pressure switch and the corresponding fitting that you will need to weld / braze onto your AC line. Plus hook up the AC request signal from X20 Pin6 to Red PCM Pin 17 or C230 - F

    Pressure switch - ACDELCO Part # 155742
    Special port - Docs Blocks - AC0146

    You will need a reversal relay on the AC request output or your AC button will work backwards. On when off and vice versa.

    You will also need to use a relay to engage the AC clutch.
    Thanks for the part numbers!

    So question.. Where does the wiring for the GM pressure switch go? Im not sure If I still have them in my harness. I want to say I remember this switch being there when I did the swap but I deleted it thinking it was something else.
    Last edited by EKnight; 03-26-2012 at 11:44 AM.

  5. #5
    Join Date
    Mar 2011
    Location
    Dallas, TX
    Posts
    764
    My Cars
    2008 535i


    This shows all of the AC wiring.

  6. #6
    Join Date
    Jun 2004
    Location
    Tigard, 0r
    Posts
    383
    My Cars
    99' 357Ls - 87' 335is
    C2 pin 14, C1 pin 45, C2 pin 57.

    Check out the last post in the FAQ thread posted above. I updated the schematic of the merged GM and BMW systems to include the reversal relay I added to my system.

  7. #7
    Join Date
    May 2011
    Location
    Memphis
    Posts
    211
    My Cars
    10 535i, 97 M3, 69 1602
    Quote Originally Posted by Pzary3233 View Post
    There is a huge FAQ thread that tells you step by step how to do it in the sticky



    http://forums.bimmerforums.com/forum...d.php?t=723277

    Also braaps thread has the wiring info. The wiring info I gave you originally has the information in it as well.
    Paul the instructions are hardly what id consider step by step - more like a jumbled mess of posts to piece through. Then theres your wiring docs which are cool however in your "Integration of LSx PCM Harness with OBD I e36 harness" it states:

    Pin 11 PCM RED C2 - DK Blue
    Pin 17 PCM RED C2 - DK Grn/White
    Pin 43 PCM RED C2 - Dk Grn/White
    Pin 55 PCM RED C2 - Dk grn

    Well Pins 11 and 55 dont even exist in my harness. Not that I cut them - they arent even in the connector. Admittedly though I am looking at your GM wiring doc and it has two columns. The one on the right is unlabeled but it does more closely match my harness... I could be looking at it wrong

    So long story short ive stared at these wires tonight and im still completely lost.

    Where do the 3 wires from the GM Pressure switch go and how do you even tell which wires are which when you buy a completely naked sensor (my harness didnt have one)?
    What wires are needed from the GM PCM Connectors to the X20 and which X20 pins do they connect to?
    Last edited by EKnight; 03-27-2012 at 03:36 AM.

  8. #8
    Join Date
    Mar 2011
    Location
    Dallas, TX
    Posts
    764
    My Cars
    2008 535i
    What year harness are you using? Out of what car?

  9. #9
    Join Date
    Mar 2006
    Location
    Memphis, TN
    Posts
    2,471
    My Cars
    95 M3, 01 330ci
    Eh all the info is there, you've gotta work for some of it

    Look at " '97 BMW Wiring" that will show you what is needed from the x20 to the PCM, all other wiring stays the same on the GM connector unless you have cut it off.

    The one on the right is for a camaro, the one on the left is a truck.

    Again it's all there, you've gotta dig for it.

  10. #10
    Join Date
    May 2011
    Location
    Memphis
    Posts
    211
    My Cars
    10 535i, 97 M3, 69 1602
    Quote Originally Posted by Kaane View Post
    What year harness are you using? Out of what car?
    The motor/tranny/harness came out of a 2002 WS6 pontiac trans am

    Quote Originally Posted by Pzary3233 View Post
    Eh all the info is there, you've gotta work for some of it

    Look at " '97 BMW Wiring" that will show you what is needed from the x20 to the PCM, all other wiring stays the same on the GM connector unless you have cut it off.

    The one on the right is for a camaro, the one on the left is a truck.

    Again it's all there, you've gotta dig for it.
    From what I understand the Camaruh and Trans-am harnesses are more closely aligned (if not the same). So that makes sense why that info on the right makes sense Thanks Paul!
    Last edited by EKnight; 03-27-2012 at 11:34 AM. Reason: Automerged Doublepost

  11. #11
    Join Date
    Mar 2006
    Location
    Memphis, TN
    Posts
    2,471
    My Cars
    95 M3, 01 330ci

  12. #12
    Join Date
    May 2011
    Location
    Memphis
    Posts
    211
    My Cars
    10 535i, 97 M3, 69 1602
    Alright so after looking over lovnbmws diagrams, talking to Kaane and rao via pm this is what I have and I think its right:

    First the pins needed:

    X20 - Pin 6 A/C "turn on signal from climate control"
    X20 - Pin 4 A/C Compressor relay?

    C2 Pin 17 A/C Request signal
    C2 Pin 43 A/C Clutch relay control
    C2 Pin 18 A/C Clutch supply voltage/status wire (this wire is connected from the PCM directly to the compressor plug, this wire isnt cut on my harness so no mods necessary right?)

    Now how to wire it up:
    X20 Pin 4 ---> C2 Pin 43
    X20 Pin 6 ---> C2 Pin 17 via Relay like so:




    and voila.. thats it I take it?
    Last edited by EKnight; 03-29-2012 at 12:21 AM. Reason: Automerged Doublepost

  13. #13
    Join Date
    Oct 2006
    Location
    Naperville, IL
    Posts
    2,462
    My Cars
    1998 540i
    You are making this a little too complicated.

    Questions:

    1. Do you have the GM pressure switch installed in our high pressure line - you can't do anything until this step is done.

    2. Have you cut any part of the LS1 harness that is shown in the diagram above?

    3. The ONLY BMW wire that you need is the AC request signal which comes through the X20 connector.

    Don't wire the relay like you have shown, it won't work.

    We can take this step by step, so post the answers to the questions above and we'll take it from there.
    Rob
    Prior projects:
    1998 540i with 6.6 LS2/T56 Chevy Power
    - pictures and details
    1992 325i with 6.6 LS2/T56 Chevy power - pictures and details
    1995 M3 with 6.6 LS2/T56 Chevy power - pictures and details




  14. #14
    Join Date
    Mar 2006
    Location
    Memphis, TN
    Posts
    2,471
    My Cars
    95 M3, 01 330ci
    Eric, like Rao said, you are over analyzing this and making it much harder then it actually is. You are letting the GM PCM control most every function of the compressor at is would in a GM vehicle. The only thing that the PCM needs is the AC Demand signal from the x20. The rest is GM wiring from my reading up on the subject this morning.

  15. #15
    Join Date
    May 2011
    Location
    Memphis
    Posts
    211
    My Cars
    10 535i, 97 M3, 69 1602
    Questions:

    1. Do you have the GM pressure switch installed in our high pressure line - you can't do anything until this step is done.

    It isnt currently brazed on but it will be this afternoon (the mobile A/C guy is coming by)

    2. Have you cut any part of the LS1 harness that is shown in the diagram above?

    The GM Pressure sensor was cut off but Ive wired it back in appropriately. I do not believe any of the other wires are cut except for the wires the previously went to the "C" connectors. IE Pin 17, Pin 43. The wires going to the ac compressor plug are still intact ie the status wire Pin 18 and its ground (i believe)

    3. The ONLY BMW wire that you need is the AC request signal which comes through the X20 connector.

    I have all of the X20 intact

    thanks again for the help

  16. #16
    Join Date
    Mar 2006
    Location
    Memphis, TN
    Posts
    2,471
    My Cars
    95 M3, 01 330ci
    Sounds like you'll have the makings for a step by step instruction post soon enough.

    Good Work!

  17. #17
    Join Date
    May 2011
    Location
    Memphis
    Posts
    211
    My Cars
    10 535i, 97 M3, 69 1602
    Quote Originally Posted by Pzary3233 View Post
    Sounds like you'll have the makings for a step by step instruction post soon enough.

    Good Work!
    thats currently the plan - to figure it out and then write it out on an 8th grade level for all to see and understand at a glance

    especially goobers like myself
    Last edited by EKnight; 03-29-2012 at 12:35 PM.

  18. #18
    Join Date
    Oct 2006
    Location
    Naperville, IL
    Posts
    2,462
    My Cars
    1998 540i
    Try this:

    Rob
    Prior projects:
    1998 540i with 6.6 LS2/T56 Chevy Power
    - pictures and details
    1992 325i with 6.6 LS2/T56 Chevy power - pictures and details
    1995 M3 with 6.6 LS2/T56 Chevy power - pictures and details




  19. #19
    Join Date
    May 2011
    Location
    Memphis
    Posts
    211
    My Cars
    10 535i, 97 M3, 69 1602
    Rao - awesome diagram but just to confirm:



    If my notes make sense and thats correct I think that solves it for me ? Thoughts?

  20. #20
    Join Date
    Oct 2006
    Location
    Naperville, IL
    Posts
    2,462
    My Cars
    1998 540i
    Sounds like you have it.

    You need to make sure that Pin C2-18 and Pin A of the AC compressor receive the same voltage at the same time.

    Both Pin 30 and 85 on the relay need to see key on +12v with a 15a fuse and wiring large enough to handle that amount of current.
    Rob
    Prior projects:
    1998 540i with 6.6 LS2/T56 Chevy Power
    - pictures and details
    1992 325i with 6.6 LS2/T56 Chevy power - pictures and details
    1995 M3 with 6.6 LS2/T56 Chevy power - pictures and details




  21. #21
    Join Date
    May 2011
    Location
    Memphis
    Posts
    211
    My Cars
    10 535i, 97 M3, 69 1602
    Quote Originally Posted by rao View Post
    Sounds like you have it.

    You need to make sure that Pin C2-18 and Pin A of the AC compressor receive the same voltage at the same time.

    Both Pin 30 and 85 on the relay need to see key on +12v with a 15a fuse and wiring large enough to handle that amount of current.
    Any recommendations on how to make sure pin c2-18 and pin a of the compressor see the same voltage at the same time?

    And what did you do for the relay+ fuse? swap a bimmer fuse or what?

  22. #22
    Join Date
    Oct 2006
    Location
    Naperville, IL
    Posts
    2,462
    My Cars
    1998 540i
    Make sure the wires are connected

    I didn't use any of the BMW relays. I used a fuse block and a relay block for all of the engine wiring.
    Rob
    Prior projects:
    1998 540i with 6.6 LS2/T56 Chevy Power
    - pictures and details
    1992 325i with 6.6 LS2/T56 Chevy power - pictures and details
    1995 M3 with 6.6 LS2/T56 Chevy power - pictures and details




  23. #23
    Join Date
    May 2011
    Location
    Memphis
    Posts
    211
    My Cars
    10 535i, 97 M3, 69 1602
    Quote Originally Posted by rao View Post
    Make sure the wires are connected

    I didn't use any of the BMW relays. I used a fuse block and a relay block for all of the engine wiring.
    Haha so just good solid connections

    Sweet ive got some stuff laying around. Ill probably do some 14 guage wire and an inline fuse+ holder dedicated to the A/C.

    hmm so looking at my harness last night, where would you guys recommend SAFELY tapping in for 12v switched? Ive run out of pre-run bmw switched wires I believe
    Last edited by EKnight; 03-30-2012 at 11:29 AM. Reason: Automerged Doublepost

  24. #24
    Join Date
    Jun 2004
    Location
    Tigard, 0r
    Posts
    383
    My Cars
    99' 357Ls - 87' 335is
    Quote Originally Posted by EKnight View Post
    Rao - awesome diagram but just to confirm:



    If my notes make sense and thats correct I think that solves it for me ? Thoughts?

    Not to confuse the issue and I know there are many ways to skin a cat but... humm... why wire in another relay when K19 is already in the car for that purpose?



    You do however need a relay for switching the polarity of the AC request signal...

  25. #25
    Join Date
    Apr 2010
    Location
    Calgary
    Posts
    19
    My Cars
    E36
    I solved it. My swap is an LS1 318 and I kept the BMW system intact during the swap so I didn't want to breach it in any way (ie didn't want to add the GM pressure sensor).

    I wired the AC request as per lovnbmws diagram above - it worked. For the pressure signal, I wired a 50 kohm resitor from the GM 5V signal to the AC pressure signal. This knocks it down to about 2.5V so the GM PCM thinks the AC pressure is in the range to turn on the compressor. However, I also wired this signal through the BMW pressure switch, which will open under high or low pressure conditions thus controlling the AC system pressure.

    With this, I have full GM compressor control - idle up, AC off under full throttle, fan control etc. And there is minimal cost and effort. The most labour was making custom mounts for the 318 compressor onto the LS1.
    1997 318i
    1997 Corvette LS1
    4L80E

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •