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Thread: BMW Transmission Position Switch Rebuild

  1. #1
    Xephius's Avatar
    Xephius is offline 665 Neighbor of the Beast BMW CCA Member
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    BMW Transmission Position Switch Rebuild

    Keyword: P0705, Transmission Position Switch, Neutral Switch, Park Switch, ZF 5HP-24

    Symptoms: The car will not display position of shifter on cluster. Car will not start. Shifter interlock (solenoid) will not engage locking shifter into position. Car will go into TFS Prog when shifting from D to P or N and the dash illuminations of PRND are all dim.

    Problem: 1) Water passes by the rubber seal causing shorts or corrosion on the contacts inside the switch. 2) The plastic switch contacts wear down causing poor connections. 3) Connector seals fail allowing water to enter the connector causing shorts.

    Seen here as part #5



    BMW Part Number 24107512755
    9/99 build date (GH83)

    To remove the switch, it is best to drive the car up onto ramps and chock the rear tires. Engage the parking brake and put the car into Neutral. It is important to test the stability of the car in N because you will be under it change the transmission from P to N and back several times. Allow the car to cool... or burn your arms... your call.

    Remove the forward and rear heat shields. This will allow enough room to slide the switch off without dropping the transmission. Otherwise, you will probably crack the plastic case trying to squeeze it out.

    Remove the shift cable retaining clip, loosen the cable locking bolt and slide the cable out and away. Remove the Shift arm retaining lock bolt. Then remove the two 10mm retaining bolts that hold the switch in place. The connector will twist to unplug.

    Once out, the process is fairly simple. Using a countersink bit, drill out the soft rivets and countersink slightly into the aluminum plate. Open the case and use an electrical contact cleaning spray to clean the contacts and displace any water present. Make sure the vent tube is cleared of any build up. Use a small amount of gasket maker on both sides of the gasket to reseal the unit. Be sure that any fasteners you use sit flush on the metal side and are locked in place. Replacement rivets are an option, but the correct size are harder to come by. I used small stainless countersunk machine bolts and nuts with red loctite. Replace in reverse order. The pictures below are not needed, but are good for reference.

    Thanks to Edwin for sending me reference material (in Dutch) and setting me on the right course.

    John











  2. #2
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    Stellar write-up, John!

    I still find it very alarming how moisture can get into the "sealed" parts of the switch. I hope this doesn't happen to mine ever again. It sucked.
    (9/94, GF61, JPN: M60B40, ZF 5HP30, 3.15:1)
    (5/06, FB53, US: N62B44, ZF GA6HP26Z, 3.46:1)

  3. #3
    meteck's Avatar
    meteck is offline Houston CCA Houston 7ers BMW CCA Member
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    Great job as usual John





    Totally stock 97 740iL except for SatRad

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    Glad it worked John!

    What's up with the small pics

    Have a technical question, don't send me a PM but post it on the board so others can benefit from it!

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    Great write-up.

    thanks for posting it.
    Were you able to see whether or not the neutral and park signals came off the same set of contacts, or different ones.
    Best regards, Hal

  6. #6
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    Saves a lot of $ some shops will say you need a new tranny

    Have a technical question, don't send me a PM but post it on the board so others can benefit from it!

  7. #7
    Xephius's Avatar
    Xephius is offline 665 Neighbor of the Beast BMW CCA Member
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    Quote Originally Posted by halbitton View Post
    thanks for posting it.
    Were you able to see whether or not the neutral and park signals came off the same set of contacts, or different ones.
    Best regards, Hal
    This switch is the N/P switch as well as for all the others.

    John

  8. #8
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    Does anyone ( Probably Edwin ) know if this is the same process for a 5hp30?

    RY

  9. #9
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    Quote Originally Posted by Xephius View Post
    Keyword: P0705, Transmission Position Switch, Neutral Switch, Park Switch, ZF 5HP-24

    Symptoms: The car will not display position of shifter on cluster. Car will not start. Shifter interlock (solenoid) will not engage locking shifter into position. Car will go into TFS Prog when shifting from D to P or N and the dash illuminations of PRND are all dim.

    Problem: 1) Water passes by the rubber seal causing shorts or corrosion on the contacts inside the switch. 2) The plastic switch contacts wear down causing poor connections. 3) Connector seals fail allowing water to enter the connector causing shorts.

    Seen here as part #5


    BMW Part Number 24107512755
    9/99 build date (GH83)

    To remove the switch, it is best to drive the car up onto ramps and chock the rear tires. Engage the parking brake and put the car into Neutral. It is important to test the stability of the car in N because you will be under it change the transmission from P to N and back several times. Allow the car to cool... or burn your arms... your call.

    Remove the forward and rear heat shields. This will allow enough room to slide the switch off without dropping the transmission. Otherwise, you will probably crack the plastic case trying to squeeze it out.

    Remove the shift cable retaining clip, loosen the cable locking bolt and slide the cable out and away. Remove the Shift arm retaining lock bolt. Then remove the two 10mm retaining bolts that hold the switch in place. The connector will twist to unplug.

    Once out, the process is fairly simple. Using a countersink bit, drill out the soft rivets and countersink slightly into the aluminum plate. Open the case and use an electrical contact cleaning spray to clean the contacts and displace any water present. Make sure the vent tube is cleared of any build up. Use a small amount of gasket maker on both sides of the gasket to reseal the unit. Be sure that any fasteners you use sit flush on the metal side and are locked in place. Replacement rivets are an option, but the correct size are harder to come by. I used small stainless countersunk machine bolts and nuts with red loctite. Replace in reverse order. The pictures below are not needed, but are good for reference.

    Thanks to Edwin for sending me reference material (in Dutch) and setting me on the right course.

    John
    GOOD information - I am beginning to think this will be my next step trying to run down my intermittent starting problem. The only reason I have not gone there to-date.....this was a very rare problem on my '01 when it was 6 mos or a year old, the dealer said there was a service bulletin to do a software upgrade. He did the upgrade and the problem went away for 4 or 5 years before it started again. It has gradually gotten worse to the point now where I sometimes wonder if it will start at all. It always has so far but not a warm and cozy feeling sometimes when far from home. The car is 10 years old but still has only 28K miles, should not be worn out.....so maybe just dirty contacts in the switch. And.... "Rowing" the shift selector does seem to help at times.

    I didn't have these problems with my Merc...........
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  10. #10
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    Quote Originally Posted by noodlesandsam View Post
    Does anyone ( Probably Edwin ) know if this is the same process for a 5hp30?

    RY
    Yes 5HP30 is the same procedure

    Have a technical question, don't send me a PM but post it on the board so others can benefit from it!

  11. #11
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    E38 No Start - Neutral Safety/Trans Position Switch Probable Cause

    Well.....some history first

    I've owned the car for some time so I know the car's behavior fairly well. Last year the car started to periodically give me the Tranny Fault code but would go away. During a VERY hot day the car decided it wouldn't start after a lengthy drive. After 30 minutes of trying all of my tricks to get the damn thing to start I decided to try rowing the shifter up and down the gears WITHOUT keeping the ignition switch in the start position (thinking it was a neutral safety switch issue). At first there was no luck….wouldn't even engage the starter or even CLICK. I then got out and rocked the car back and forth whilst the shifter was in Park to see if there was some kind of sensor that wasn't engaged fully, then tried starting whilst rowing the shifter back and forth….it started! However, the Transmission Fault code appeared with all the nice 3rd gear performance.

    The car didn't exhibit ANY issues until late in the fall…prior to being put away for the winter. I thought I had cleared this problem up by dropping the oil pan and tightening the VERY lose oil pump bolt…but that's another story.

    Fast forward to three weeks ago. Wife drives car primarily and tells me that the Fault code showed up AFTER she had the car parked on our incline drive way. After doing her short trips she then parks car in garage…with NO START as a result. So lets see…Tranny Default code AND No Start. At first, my thoughts given all that I knew….EWS was cause. Hey….Googling these symptoms many times makes you chase unrelated issues…right? So…yesterday I'm trolling for HOURs on the different boards and find this post for Neutral Safety Switch ailments…..and I go down stairs to get medieval on the shifter because I DON'T want to pay the BMW thieves any cash to tell me that I've got to raise my DEBT CELING to fix my decade old car…that I love so much. After my fifth run through the gears whilst holding the ignition in the start position…I start hearing CLICKS and then VROOM! I proceeded to drive the car up the street to make sure I wasn't dreaming and of course I was welcomed with the Tranny Fault code plus 3rd gear only. I went back to the house…shut car down, pulled key from ignition and opened driver's door. Put key back into ignition and started car with NO fault code showing. Nice.

    I've NOT pulled the switch assembly out yet BUT I'm fairly certain that this is the culprit given my now "enrichened" knowledge of the system (plus EWS system design). I will do the service next weekend and will post my findings. Note….Tranny Fault code would show up when wife used Sport mode shifting….another reason for me to question this sensor.

  12. #12
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    It's not just the sensor it also controls any movement of the shifter.

    You can do it Johns way or buy a new one

    Have a technical question, don't send me a PM but post it on the board so others can benefit from it!

  13. #13
    Xephius's Avatar
    Xephius is offline 665 Neighbor of the Beast BMW CCA Member
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    As an update (Edwin please C&P into the HowTo)..

    Please check the wires where the drain tube is clipped to the wire harness. After rebuilding my switch I drove through a puddle and had the same problem happen. After stripping all the cable jacket off, I noticed that the drain tube is held to the wires via a small plastic clip that will wear the wire insulator off the two wires. After I repaired that, the problem went away. Mind you, I have taken the switch off and put it back on over 20 times by now.....

    John

  14. #14
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    Exactly what I was looking for... I'll try this it seems to get worse when it drives thru a puddle. Subscribed

    1970 Morris Cooper * 1973 Mini Clubman 1275GT * 2008 BMW 135i Coupe 2008 BMW 128i Cabriolet * 1995 BMW M3

  15. #15
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    Update I had no time to do this rebuild had it replaced and cost $480 parts and labor.

    1970 Morris Cooper * 1973 Mini Clubman 1275GT * 2008 BMW 135i Coupe 2008 BMW 128i Cabriolet * 1995 BMW M3

  16. #16
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    Nice work, but I'd rather just grab another switch from a junker and replace. Unless you enjoy detailed work like this of course.

    02 e39 540i Sport (Son), 01 DINAN 7 (Me), 12 e70 X5 x35i (Mrs), 95 e34 525i (Daughter 2), 01 e46 325Ci vert (Daughter 1)

  17. #17
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    Update car is now awesome no more issues!

    1970 Morris Cooper * 1973 Mini Clubman 1275GT * 2008 BMW 135i Coupe 2008 BMW 128i Cabriolet * 1995 BMW M3

  18. #18
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    I am unable to view your pictures. I would be most appreciative if you could repost, or send me a copy. Thanks in advance.

  19. #19
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    Quote Originally Posted by cranefighter View Post
    I am unable to view your pictures. I would be most appreciative if you could repost, or send me a copy. Thanks in advance.
    It was from Realoem:

    http://www.realoem.com/bmw/enUS/show...diagId=24_0720
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  20. #20
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    *bump* Some additional info:

    Another failure mode of these switches is wear of the cam inside. The leaf spring inside puts pressure on the cam from the back and holds it in place so the slots can operate the contacts. The back of the cam rides against a boss on the metal side. The cam wears here resulting in the cam riding at a slight angle rather than flat.

    I recently rebuilt such a switch and rememdied the problem by making a thrust washer from 0.020 aluminium sheet. After cleaning everything the whole inside was coated with INOX, the cam was lubed with dielectric grease, the thrust washer (same ID and OD as the seal boss the cam rides against) was also lubed with grease, and finally grease on the case seals (shaft and perimeter seals).

    Reassembly used brass wood screws bradded into place to replace the rivets. Installed on the car and no more P0705.

    -Mike O.

  21. #21
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    Super old thread I know, but is this what is happening to me here?

  22. #22
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    Quote Originally Posted by purplecty View Post
    Super old thread I know, but is this what is happening to me here?
    Were you able to pull a code?
    In my case replacing this switch cured my trans fail safe and gear selector indicator issues. My INPA code was 60 I first purchased a used one it lasted about 3 months before it failed. Came from the same year and model as my car so no surprise it didn’t last very long before it failed. I then purchased new from fcp and no issues since.


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  23. #23
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    Quote Originally Posted by haynes740 View Post
    Were you able to pull a code?
    In my case replacing this switch cured my trans fail safe and gear selector indicator issues. My INPA code was 60 I first purchased a used one it lasted about 3 months before it failed. Came from the same year and model as my car so no surprise it didn’t last very long before it failed. I then purchased new from fcp and no issues since.


    Sent from my iPhone using Tapatalk




    Sent from my iPhone using Tapatalk
    2001 740iL Guides,chains,vanos done. Full steptronic retrofit,3:15 diff. DUDMD tune. Sport seat retrofit. Porn lights
    [IMG][/IMG]
    Nitto ZR 285/40/18 rear 245/45/18 fr. UUC springs front. Porn lights. Sport wheel


    1991 735iL UUC springs front only Style 42 wheels

  24. #24
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    Mine actually happened to be the shifter lock was not locking properly. Something seemed to be sticking and gear shifter could be moved without pressing on the brake. It locked back in and started functioning properly again and the indicator is back to normal and no more trans failsafe...

  25. #25
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    Quote Originally Posted by purplecty View Post
    Mine actually happened to be the shifter lock was not locking properly. Something seemed to be sticking and gear shifter could be moved without pressing on the brake. It locked back in and started functioning properly again and the indicator is back to normal and no more trans failsafe...
    Wonder if you need to adjust the shift linkage cable. Mine is a little loose too!


    Sent from my iPhone using Tapatalk
    2001 740iL Guides,chains,vanos done. Full steptronic retrofit,3:15 diff. DUDMD tune. Sport seat retrofit. Porn lights
    [IMG][/IMG]
    Nitto ZR 285/40/18 rear 245/45/18 fr. UUC springs front. Porn lights. Sport wheel


    1991 735iL UUC springs front only Style 42 wheels

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