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Thread: Using BMW DBW Pedal on LS3 Conversion

  1. #1
    Join Date
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    '88 635 CSi, '09 X5 4.8

    Using BMW DBW Pedal on LS3 Conversion

    My LS3 conversion utilized a corvette dbw pedal. Even though I made a custom bracket to get the placement very close to the stock pedal, the hinge point (overhung vs floor hinged) really didn't feel quite right and made heel toe operation more difficult. After doing some research I found that both pedals utilize two separate variable resistor circuits with one at half scale of the other. The attached video shows a mockup harness aligning sensor circuits on each. Although the voltage readings are slightly different between the two pedal it works fine in the garage without throwing any codes. I used my HPTuners to verify that the throttle is going to WOT (80%). Next step is making a long jumper harness, reinstalling the BMW pedal and driving once the polar vortex finally relents.

    Shea Burns

  2. #2
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    '95 M3, 97' E39 540i-LS3
    That's really neat.
    I contemplated going there for about a minute and then imagined a tar pit project and un-intended acceleration. I don't like my pedal placement so you've got my attention.
    540i-LS3-TR6060 swap thread

  3. #3
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    Quote Originally Posted by zr6sbc View Post
    That's really neat.
    I contemplated going there for about a minute and then imagined a tar pit project and un-intended acceleration. I don't like my pedal placement so you've got my attention.
    I can't picture any scenario where you'd get un-intended acceleration (NASA couldn't even make it happen without floor mats on Toyota's). If the ECU sees something it doesn't like it will simply kill the throttle. Of course that wouldn't be much fun in the middle of an intersection...

    To clarify for anyone looking to try this, I'm using a later 6 wire system on a GM E38 ECU. This would likely be different on earlier Gen III based systems with a TAC module. Not sure that it matters, but the OS on my ECU is from a 2009 Vette.

    GM Accelerator Pedal Position Sensor Pinout (wire colors will vary depending upon whether the harness was custom (like mine) or built from stock)
    A - Low Reference
    B - APP Sensor 2 Signal
    C - 5-Volt Reference 1
    D - Low Reference
    E - APP Sensor 1 Signal
    F - 5-Volt Reference 2

    E46 Pedal Pinout
    1 - Gnd 1 - Brn/Grn
    2 - Gnd 2 - Brn
    3 - VCC 2 - Yel/Grn
    4 - Sig 1 - Wht
    5 - VCC 1 - Yel
    6 - Sig 2 - Wht/Grn

    I have it connected as follows;
    A - 1
    B - 6
    C - 5
    D - 2
    E - 4
    F - 3

    APP Readings from HPTuners are in % (I believe this % of control voltage ~5V) and were as follows.

    GM Pedal
    AP1 18% - 84%
    AP2 9% - 42%

    BMW Pedal
    AP1 15% - 78%
    AP2 7% - 39%

    The TPS values with the engine off (again % of voltage not actual throttle position) were as follows:
    GM Pedal - 29% - 84%
    BMW Pedal - 22% - 80%

    Once started they both read ~22% at idle (ECU is controlling at that point) and ~80-82% at WOT. So... they are damn close and I think the ECU is compensating for the small resistance difference.
    Shea Burns

  4. #4
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    So basically the BMW is "plug and play" with the GM throttle control unit just by connecting the 6 wires?
    This is awesome!

    Any plans to tackle crusice control?

  5. #5
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    Quote Originally Posted by Keith1054 View Post
    So basically the BMW is "plug and play" with the GM throttle control unit just by connecting the 6 wires?
    This is awesome!
    Looks that way...

    [/QUOTE]Any plans to tackle crusice control?[/QUOTE]

    That will require a CAN solution or some custom switches. Thaniel is looking into that in one of his threads.
    Shea Burns

  6. #6
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    Quote Originally Posted by ssburns View Post
    To clarify for anyone looking to try this, I'm using a later 6 wire system on a GM E38 ECU. This would likely be different on earlier Gen III based systems with a TAC module. Not sure that it matters, but the OS on my ECU is from a 2009 Vette.

    GM Accelerator Pedal Position Sensor Pinout (wire colors will vary depending upon whether the harness was custom (like mine) or built from stock)
    A - Low Reference
    B - APP Sensor 2 Signal
    C - 5-Volt Reference 1
    D - Low Reference
    E - APP Sensor 1 Signal
    F - 5-Volt Reference 2

    E46 Pedal Pinout
    1 - Gnd 1 - Brn/Grn
    2 - Gnd 2 - Brn
    3 - VCC 2 - Yel/Grn
    4 - Sig 1 - Wht
    5 - VCC 1 - Yel
    6 - Sig 2 - Wht/Grn

    I have it connected as follows;
    A - 1
    B - 6
    C - 5
    D - 2
    E - 4
    F - 3

    APP Readings from HPTuners are in % (I believe this % of control voltage ~5V) and were as follows.

    GM Pedal
    AP1 18% - 84%
    AP2 9% - 42%

    BMW Pedal
    AP1 15% - 78%
    AP2 7% - 39%

    The TPS values with the engine off (again % of voltage not actual throttle position) were as follows:
    GM Pedal - 29% - 84%
    BMW Pedal - 22% - 80%

    Once started they both read ~22% at idle (ECU is controlling at that point) and ~80-82% at WOT. So... they are damn close and I think the ECU is compensating for the small resistance difference.
    Great detail. Thanks. But you should have just put on a carb....Just kidding.

  7. #7
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    Quote Originally Posted by Thaniel View Post
    Great detail. Thanks. But you should have just put on a carb....Just kidding.
    And a giant analog tach on top of the dash...
    Shea Burns

  8. #8
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    You got me looking at pedals. It looks like there were manual trans versions and auto versions. I'd guess they have different ramps. It'd be nice to know the difference.

    In HPTuners, can WOT be set for a particular pedal output?
    540i-LS3-TR6060 swap thread

  9. #9
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    Quote Originally Posted by zr6sbc View Post
    You got me looking at pedals. It looks like there were manual trans versions and auto versions. I'd guess they have different ramps. It'd be nice to know the difference.

    In HPTuners, can WOT be set for a particular pedal output?
    I wasn't aware that there were different pedals for man vs. auto. I wonder if this is just geometry. The ramp rate of the resistance/voltage in the pedal should be pretty linear even if the range is different. Yes. HPTuners has a table to control throttle opening vs. pedal position and RPM (or vehicle speed).

    Picture1.png
    Shea Burns

  10. #10
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    I looked at this with my '99 e39 and GenIII truck PCM/TAC, and nothing really matched up. Cool you got it working for the newer stuff!
    '99 BMW 540i6 L33 5.3, PRC Heads, E-force supercharged
    http://forums.bimmerforums.com/forum....php?t=1674320

  11. #11
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    I hope to get this working on my Z3 coupe. The later years were DBW as well on the 3.0

  12. #12
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    An update for this solution.

    For 2 years I've had no issues with my pedal solution, but early this summer I had a couple occasions where the I would get a CEL and the throttle would become unresponsive. Once I turned the car off and waited ~10 seconds to restart the throttle would work again. When I checked the codes I was getting P2127 which indicated that there was a problem with the accelerator pedal sensors. Since the pedal I was using was original to the car and they are pretty cheap I bought a new one. Unfortunately the issue became more frequent.

    In doing some research I found this document http://hsv-gts.ls2.com/0506GTODTC/DTC%20P2127.pdf. This part caught my attention "The APP sensor 2 voltage is less than 0.3625 volts for more than 1 second". When I checked the voltage of APP 2 on the new pedal (using HPTuners) it was just barely above the 0.36 volts and if I depressed it and let it snap back it dipped just below it. I then checked the older pedal and it was slightly higher, but still very close.

    So I open up the pedal assembly to see if I could adjust it at all (you'll need a special torx bit for this). In the picture below the yellow part is a cylindrical piece of foam the that serves as a stop at the 0% pedal position. It can compress a bit and indeed on the older pedal it had even formed somewhat of a dent. Which might explain why I hadn't had issues before, but was now.

    My solution was to glue a shim (circled in red) to up the voltage slightly. I played around with a couple different thicknesses, but ended up using a piece of a CD case which raised the voltage ~0.15V. I verified with the HPTuners that this wasn't enough to command any actual throttle movement. So idle isn't affected. After ~3 months no issues.

    Given that there is some pedal to pedal variability you might want to check this up front and shim if its too close to the threshold.

    pedal 2.jpg

    - - - Updated - - -

    Also in another thread it was confirmed that the BMW pedal will not work for earlier GEN III controllers with TAC modules. The GM pedals for that setup had 3 sensors (one with ascending voltage and two descending).
    Shea Burns

  13. #13
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    Intresting. The Z3 has a
    different sensor that that. It's this little cylinder that's actuated with a rod from the pedal.

    I will be using a AEM infinity so it should be able to pick up many pedal / TB combos I would think.

  14. #14
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    e39 m5, 72 duster
    Nice work. The stock bmw wiring you mentioned went to the dme right? I have to figure this out on an m5 which has a different throttle sender. That would be awesome if the wire colors were the same. Good info either way.

  15. #15
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    Made from aluminum and stainless steel, the pedal has a splined pedal arm that allows for versatile mounting and can be installed as either a typical hanging orientation as seen here or turned over for a floor-mount setup. As an assurance that you’re getting the highest quality of components, the pedal kit includes a wiring harness from Painless .

  16. #16
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    Yes, they go straight to the DME. Bentley manual will give you the BMW wire colors.
    Shea Burns

  17. #17
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    Reviving a thread for those that are searching now.. (This info is becoming more and more pertinent with E46s getting cheaper and cheaper)

    Quote Originally Posted by zr6sbc View Post
    You got me looking at pedals. It looks like there were manual trans versions and auto versions. I'd guess they have different ramps. It'd be nice to know the difference.

    In HPTuners, can WOT be set for a particular pedal output?
    As far as I can tell, the "ramp rates" are the same between auto/manual. Pedals are identical - There is a pair of sensors in the 'core' of the pedal that act similarly to the GM stuff - one ascending sweep, the other descending. The automatic version of the pedal includes a simple "clicker" for lack of a better term so that you get a small and subtle detent right before WOT - This presumably provides the driver feedback allowing them to get to WOT without asking for the trans go into "kick-down" mode.. (upper range in the pedal).

    You can actually 'convert' an auto pedal to a 'manual' pedal by opening it and removing the "clicker"..

    Quote Originally Posted by ssburns View Post
    An update for this solution.

    For 2 years I've had no issues with my pedal solution, but early this summer I had a couple occasions where the I would get a CEL and the throttle would become unresponsive. Once I turned the car off and waited ~10 seconds to restart the throttle would work again. When I checked the codes I was getting P2127 which indicated that there was a problem with the accelerator pedal sensors. Since the pedal I was using was original to the car and they are pretty cheap I bought a new one. Unfortunately the issue became more frequent.

    In doing some research I found this document http://hsv-gts.ls2.com/0506GTODTC/DTC%20P2127.pdf. This part caught my attention "The APP sensor 2 voltage is less than 0.3625 volts for more than 1 second". When I checked the voltage of APP 2 on the new pedal (using HPTuners) it was just barely above the 0.36 volts and if I depressed it and let it snap back it dipped just below it. I then checked the older pedal and it was slightly higher, but still very close.

    So I open up the pedal assembly to see if I could adjust it at all (you'll need a special torx bit for this). In the picture below the yellow part is a cylindrical piece of foam the that serves as a stop at the 0% pedal position. It can compress a bit and indeed on the older pedal it had even formed somewhat of a dent. Which might explain why I hadn't had issues before, but was now.

    My solution was to glue a shim (circled in red) to up the voltage slightly. I played around with a couple different thicknesses, but ended up using a piece of a CD case which raised the voltage ~0.15V. I verified with the HPTuners that this wasn't enough to command any actual throttle movement. So idle isn't affected. After ~3 months no issues.

    Given that there is some pedal to pedal variability you might want to check this up front and shim if its too close to the threshold.

    pedal 2.jpg

    - - - Updated - - -

    Also in another thread it was confirmed that the BMW pedal will not work for earlier GEN III controllers with TAC modules. The GM pedals for that setup had 3 sensors (one with ascending voltage and two descending).
    As another, simpler fix for this... the yellow rubberized pedal stop is easily removable (slide it out towards the camera in this view). You can simply rotate the piece of rubber and stuff it back in so the deformed area is now opposite what's being used. Simple simple simple.
    Write "Wash Me" on my car and I'll write "Resuscitate" on your chest.

  18. #18
    Join Date
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    2003 M3
    Just wanted to post a quick reply and say thank you to everyone for this thread. I am completing my LS3 swap and have a custom harness made with a BMW drive by wire pigtail wired into the new harness. Couldn’t of done that without this thread. I will post my results when It’s completed.

    EDIT 2/13/2020: Throttle works perfectly. I have ran a couple events at Sebring and Barber.
    Last edited by razormy; 02-13-2020 at 08:54 AM.

  19. #19
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    Capture.PNG

    Bumping this. I have an LS2 so I'm going to try this one out.

    Status: Someone put glitter in my oil. Wait. Why's all my oil outside the engine? What's that knocking?

  20. #20
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    Great info! I wish I found this thread before mounting the c7 pedal lol

  21. #21
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    2000 bmw 528i/94 318i
    Great info indeed! In the works of getting everything together for an ls2 swap into my topaz blue 540i and now I know that getting the GM pedal into the bimmer may not have to be my only option.

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