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  1. #1
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    Default Transmission Control Module (TCM) Location & Shielding GS/RS

    As you all know I have been going crazy and spending crazy amounts of money trying to fix my GS's transmission getting stuck in a gear and going into neutral.

    REVIEW:
    1. Gets stuck in any gear or shifts into neutral
    2. No response from paddle
    3. NO CODES
    4. New gearbox Position sensor & throttle body sensor & paddle switch assembly!
    5. Linkage is solid
    6. When you shut off engine to reset computers, the BEEPING does NOT happen when parking brake NOT engaged!?

    #6 I have to give credit to my wife! She pulls over on her RT when my GS locks up. I flip the key off and she asked why wasn't it beeping. I had never realized it. So that was maybe clueing me in on the computer being frozen up some wiring short or noise. I saw BRP had issues with electrical noise on the 2008-2010 models, and installed some grounds on the coil. So I investigated and my GS did have the grounds. The only thing really left in my case is the TCU - the computer itself. The service manual showed it in a picture, but it was really hard to tell where it actually is. I found no help on the webs, so when I tracked it down I thought I would post a few pics so someone else can search and find this thread. I thought I would try to make the wiring more noiseproof as a shot in the dark before buying a used TCM, so this is my story.

    Removed upper tupperware from left side. TCM is mounted to the front of the bike in the center. Mounted with 2 10mm bolts at top, tilts out to be removed. Light is shining on it in the pic. Zoomed in you can see it says "TCU" on it. One large connector.

    Looking at the shift module's connector (under the coil) I saw that the wiring harness was about 1" away from the noisiest place on the bike - the coils. Following it along it passed next the to diode rectifier - the second noisiest thing on the bike. So I went all out, clean connectors, re-routed harness away from coils & rectifier, wrapped a ground around the whole harness itself, and even put metal plates on the back and front of the TCU to shield it. All this didn't work but maybe if you have similar problems this will help you get to the TCU quickly.

    tcm2.jpgtcm1.jpg

    Last attachment is re-routed harness, with a ground wrap on it grounded at the TCU. I ordered a used TCU on EBay, here's hoping...

    EDIT:
    Did not work. Went to examine the coil grounding from BRP tech update and found they used a skinny 18AWG or 20AWG wire (see the RED arrow). Me being an over-achiever decided to do this better. I got some grounding cable and lugs at the hardware store. The cable is a fat 8AWG with lots of strands, designed for being a ground. Crimping the lugs took some effort with giant channel locks and big C-clamp. I ran another ground from the coil straight to the battery (see GREEN arrow), bypassing all the possible corroded grounds between the frame, engine and the battery. Finally, because I am crazy, I saw a small plate in the lumber hardware section that fit next to the coils well. I moulded it a bit by hand to fit. I made another ground lug with a small diameter solid wire wo weave though it. After attaching all the lugs at the coil, I added the plate and hot glued it in place.

    My thought was (from an engineering standpoint) that a battery ground direct to the coil would guarantee a zero ohm connection to carry the noise away, as a battery is technically an infinite capacitor. After about 200 miles, not a hiccup so far. Before I could not go 2 miles without it locking in gear. Here's hoping!
    Attached Images Attached Images
    Last edited by stevencovert; 02-04-2019 at 02:27 AM. Reason: Working ?!?

  2. #2
    Ozzie Ozzie Ozzie Peter Aawen's Avatar
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    Just a stab in the dark, but have you tried grounding both ends of that wrap around??
    2013 RT Ltd Pearl White

    Ryde More, Worry Less!

  3. #3
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    You are only supposed to ground the end of a cable that connects to the electronics. That way the electronics can help adjust on the fly to cancel out the noise

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