In The Shop: Twist Grip Sensor Issues

Twist Grip Sensor Issues

In recent years, Harley Davidson has eliminated the need for throttle cables on a number of their models. The throttle, instead, is governed by wire and is now part of the motorcycle’s electrical system. Elimination of throttle cables allows for a cleaner look around the handlebars. It is also one less thing that needs to be inspected, maintained, and adjusted.

There are three main components that work together in order to create throttle in a throttle by wire assembly:

(1) The twist grip sensor
(2) Induction module/throttle control actuator
(3) The ECM (electronic control module)

We mention induction module and the throttle control actuator together because Harley’s’ can only be purchased as one component. They share the same part number and there is no instruction to separate one from the other. In fact, we highly recommend not tampering with the throttle control actuator in any way.

The twist grip sensor has two sets of magnetic sensors that send signals to the electronic control module. The ECM controls all electrical functions on the motorcycle. It allows the twist grip sensor to communicate with the throttle control actuator. The actuator includes a geared permanent magnet DC motor and two sealed automotive style throttle position sensors which are located on the induction module body.

Harley’s throttle by wire assembly can have issues. If there is an error, the system will go into one of three different failure modes. If one signal is lost from the twist grip sensor, the ECM will put the motorcycle into limited performance mode. In this mode, throttle response is slower and full performance is impossible to achieve.

If both signals are lost from the twist grip sensor, the ECM will not be able to determine what the operator is wanting to do. The ECM will then go into forced idle mode. In this mode, there can be only slightly more throttle over idle. However, you should be able to get the bike through a few gears as there is also some spark advance allowed.

If the DC motor is lost in the throttle actuator or one or both of the throttle position sensors are lost, the ECM will put the bike into “limp mode”. This mode limits the motor to only an idle. “Limping” home will be difficult but possible. Just hope there are no steep hills along the way.

Look For The Code

If your Harley is experiencing any of these symptoms, there will, almost always, be a corresponding diagnostic error code. The code you find may help you to determine the origin of the failed signal.

The majority of the time, it has been our experience to find a bad twist grip sensor. We have, however, also diagnosed bad throttle actuators, ECM’s and worn pin connections at the throttle control actuator. It is very important to have access to an electrical manual for your year and model when trying to diagnose any of these issues.

More videos on Fuel Injectors, Intake Seals, Throttle Body

Watch the Top End R&R videos for removal and install of throttle body.
and the Twin Cam Harley Intake Seals and the Cobra EFI model on the XL Models.
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33 Responses to “In The Shop: Twist Grip Sensor Issues”
  1. Warren Ramsey
    Warren Ramsey

    Changed handlebars on a 2009 flhx. Also changed out the tbw sensor. Connected all connections back together. Tried to start bike. Bike will turn over but will not start

  2. Dale long
    Dale long

    I would much rather have cables. Very little maintenance and should last the lifetime of the bike. Electric throttles can easily malfunction requiring professional assistants and very expensive to fix. I don’t see this as an improvement.

    • Scott Hughes
      Scott Hughes

      I’m experiencing “surging” automatic acceleration bursts. Do you think that this could be caused by a bad twist grip sensor? 2012 Roadking.

        • bigfoul1962

          on the later i think2008 thet changed the little part that was just a sensor easy fix on earlier efi setup hut then harly nwillie needed more n now well thankgod for Fallen cycle used parts new induction module fancy name for carb new ones 750 thank s got mine like new for 100 bucks

  3. Howard Stumpf
    Howard Stumpf

    Also, if one gets apes, one must use the Harley extended wire or the resistance changes in the wire and will not work. I am not an expert at this as you all are, so I know you know what I am talking about. I had a lot of problems with this as I was adding 15″ apes and had to extend the cables for the Twist Grip Sensor. Would you all discuss this issue?

  4. LEO

    I have a 2015 Road King with TGS issues, I took it to the dealership and they’re diagnosing the ECM may have gone bad…which means I may be $500+ in the hole. Technology is great until it isn’t I guess.

    • LEO

      Fastforward to Aug 2018, my Road King had its TGS swapped and the error codes went away for a few months; guess what? They’re back again like a chronic rash! I’m super ticked off this is a recurring problem. Makes me think whether I should swap it for a mechanical throttle sensor…

  5. gmnpajasso

    I was looking for a step by step video to install the TPS on my 2008 Electric Glide Standard.

  6. LEO

    I just had my twist grip sensor swapped on my 2015 Road King. I wanted to do it myself but I wasn’t sure it was the culprit of my check engine trouble codes. Turns out I was right but I ended up having my dealership do it for me. Good thing is, no more check engine light warnings anymore!

  7. Matthew Walter Hardisty
    Matthew Walter Hardisty

    My 08 ultra classic cvo has a throttle drops to idle,and if I shut it off and restart it I get throttle back for a short time,but it drops back to idle.any ideas?

  8. tom t
    tom t

    2014 FLHTK rpm stays at 3500 then goes to IDLE back to 3500 or so HAVE TO SHULT OFF TO STOP. NO CODES GRIP SENSOR THIRD ONE IN 60,000 MILES. any one have this happen.its happen on all 3 of the bikes I had.all about the same miles I do a lot of dirt roads.

  9. Tony Baeza
    Tony Baeza

    Im looking for adjustment spec for 2013 throttle position sensor ultra classic

    • William

      I have a 14′ street glide. It’s doing the exact same thing. If I force the butterfly open with my finger, it starts right up but then dies again. Other than that it will not start.. did you ever figure the problem

    • Customer Service
      Customer Service

      Bonjour Jacques!

      Nous aimerions aider! Pourriez-vous expliquer ce que vous recherchez? Aussi, quelle est l’année, la marque et le modèle de votre Harley? Je transmettrai tout cela à notre expert!


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  10. adolfo

    Hello there, in advance sorry for my english. I just did change my handlebars in my FLHP 08 and I found 2 sets of wires in the TGS the main with 6 cables I believe are the actual sensor cables, but what about the second with only 2 (B & W) what is this for? in the wiring diagrams does not show.

  11. Cagle

    2017 Softail slim riding along no issues. Suddenly dead throttle and bike cuts off if I don’t grab the clutch could this be a twist grip sensor problem or something further? I restart the bike the problem goes away for quite a while

    • Customer Service
      Customer Service

      Hello Adam!

      That’s a great question!

      The ‘Ask an Expert’ section is currently for members to our online community. We do have a promotional offer if you are interested. This would include access to expert advice (like this), plus discounts, hours of Premium videos, etc. Please feel free to take a look. You can message us right back with your question if you decide to become a member and you will have a response within 1-2 business days from our experts!

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  12. Amanda Holland
    Amanda Holland

    Have a 2015 Road Glide special. Changed bars and now no throttle and cruise flashes yellow. Grrrrr