Thruxton Twist Grip Codes P2125 & P2138

Went out for a quick ride on my 2017 Thruxton. I have a little over 8,000 miles on it. I pulled over because I wanted to take my wallet out of my back pocket and put it into the zippered pocket of my jacket. When I gave the throttle a twist to pull back onto the road, I immediately got a check engine light and traction control light on the speedo. The engine was running at about 2,800 RPM for limp home mode. I pulled into a parking lot to turn the bike off and try a restart. The two caution lights stayed on and the bike engine continued to run in limp home mode high RPM. I needed to clear the codes to reset the ECU. I remembered that under the seat, the battery negative cable has a quick disconnect plug that can be used to disconnect the battery from the ECU, thus allowing an emergency on-the-road reset. I disconnected the battery negative cable and let the bike sit for about 5 minutes. I reconnected the battery and switched the bike back on. The check engine light stayed on, but the throttle was once again working normally. I rode straight home and connected the bike to my laptop using my Dealertool program. I had the following codes: P2125 - Twist grip position sensor 2 short circuit to ground or open circuit, & P2138 - Twistgrip position sensor 1 & 2 correlation malfunction. When I went to check the twist grip sensor values at idle, my bike was showing Twistgrip #1 volts of 1.29 volts, Twistgrip #2 volts of 1.52 volts. TPS #1 volts of 0.65 volts & #2 TPS volts of 1.52 volts. It also shows that the twistgrip is adapted. I am thinking a bad connection somewhere. I replace the throttle grip switch last year as i thought it was causing an ongoing high idle issue. Changing the twist grip switch did not fix that issue. It turned out that a re-flash of the ECU did the trick. Anyone else out there but me have any issues similar to this? Anyone have any other thoughts than checking wiring connections? I am open to any valid ideas. Thanks.

 

Is there anyone out there with any experience with this issue?

 

Thanks Joe. I have gone over all connections from the twist grip to the ECU. All connections are solid and all wire harnesses wring out good when I use my Fluke multi-meter on them. I live in Iowa over here in the USA, so not a lot of late model Triumphs over here. The nearest dealership has not experienced this issue, so no helpful info there either. I will post here when and if this issue occurs again.

 

I just recently read in another forum that another rider that had the same issue was told by dealer that it was a bad twist grip switch ground. i will review my wiring diagrams to locate it and make sure its not a loose ground causing the issue.

 

So I went through all the entire wire harness assemblies and verified connections and routing. No issues were evident. I did the calibration task of starting bike from cold and letting it idle until the cooling fan came on, and then without touching the throttle, let it idle for another 15 minutes. Then I shut it off and let the bike cool down completely. I gave the bike a bath, and then started it up and proceeded to put about 120 miles on the bike. A mixture of city and country riding. No issues with the twist grip sensors and performed flawlessly, Hopefully the electronic gremlin has moved on to its next victim. I'll be sure to post here again if the gremlin comes back to haunt me. One thing I did learn is that there is not a whole lot of experience out there yet when it comes to the new Throttle by Wire systems out there.

 

Hi Joe. Iowa is a friendly state. We all seem to know each other one way or another. I have bikes with throttle cables, and now one with throttle by wire. They all have their good points and bad points. I like them all.