Twist Grip Sensor Issues
In recent years, Harley-Davidson has eliminated the need for throttle cables on a number of their models. Instead, the throttle 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.
Handlebar Project Reviews The Twist Grip
Heated Grips Project
Troubleshoot with Harley Error Codes
2017Street Glide FLHX Did a 300 mile RIDE a couple of weeks ago and about 2 miles from the house BIKE surged all by itself, check engine came on(BIKE stiil running). Get home, check codes-2138 & 1510(tps out). So change out the trottle body(tps intergated in thottle body). Complete process(new thottle body & intake) and BIKE is running good, idle better, sounds better, etc. BIKE started surging just a bit last RIDE, no check engine light? Question-replace twist grip sensor?
I have installed 2 different twist grip sensors for first one kept going into limp mode after a few miles. Second one Is after market and it usually has two red 2white and 2 black 1 set with yellow sheath one the other without sheath. On this after market and extended set I have 1 red 1 black and one white w/ yellow sheath on the other is red w/white stripe white w/ red stripe and white w/black strip. I'm not sure which is black white and red ? Is it the stripe that's red white and black or is the wire color the color, for example the red goes to brown and not sure if it's the red wire with white stripe or white with a red stripe. It doesn't start like I have it and I made the red with white stripe the red wire. The set in yellow sheath go to red purple and gray and with out sheath are brown blue and black. Wondering If I crossed a wire . Any info to test theory on a meter would help if colors only confuse things
have a p2122 code, replaced tbw sensor, still get same code, tried another tca, still get same code
I have a 2020 softail standard, and I can't find wear the small cable from the horses is located
I had 2 broken wires in the wire harness at the right side frame between the gas tank and fairing. The harness was routed in a very tight "S" pattern. I repaired the 2 wires and rerouted the harness. Problem solved. Hope this helped, Ray.
Have a 2015 Road Glide special. Changed bars and now no throttle and cruise flashes yellow. Grrrrr
This was very helpful.
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
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. Thanks!
Je chercher ceci svp