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Discussion Starter · #1 ·
I'm in the process of troubleshooting Shift Assist problems with my 2015 S1000RR.

Can anyone provide the pin-out and electrical specifications for the shift rod sensor (23418549125)? It would be helpful to know which pins are Vref, Vsignal, and ground, and what the expected Vsignal levels are supposed to be.

I think I've narrowed it down to part failure, but would like to confirm before I start spending money on replacement parts.

For the interested, curious, or anyone who might have other troubleshooting ideas, here is where I'm at:
1. Clutch micro-switches are good. Action confirmed via GS-911. Action is tight, no bump or wind activation. Yes, it has modified levers (2014 HP levers).
2. Gear adaptations have been reset with GS-911. Multiple times.
3. Throttle twist grip adaptations have been reset with GS-911.
4. Wiring harness continuity from ECU to shift rod connector has been confirmed. An intermittent failure that only presents when hot or being vibrated might have been missed. Now that the failure appears consistent, will check this again.
5. Connectors at ECU and shift rod have been cleaned and greased. (Separate forum had reports of FOD in the connectors)

Symptoms: Failure now presents as consistent (I think), but over the preceding months it had been intermittent. After starting the bike, upshifting with shift assist works perfectly. Can run it up multiple gears with quickshifter, bring it back down by clutch, and go back up again with quickshifter. However, downshifting with the quickshifter fails the first time (now). Once that failure occurs, all quickshifting, both up and down, stops working. Power-cycle everything, restart, and quick upshifting comes back on.

Speculation: The downshift (compression) sensor channel has failed.

When originally troubleshooting this, GS-911 reported:
21F672 : Shift lever sensor, implausible voltage
....ADC voltage Gear lever position sensor channel 1 : 3.64 V
....ADC voltage Gear lever position sensor channel 2 : 3.58 V
....Gear position sensor voltage : 0.28 V
21F670 : Shift lever sensor, voltage above threshold
....ADC voltage Gear lever position sensor channel 1 : 3.67 V
....ADC voltage Gear lever position sensor channel 2 : 3.63 V
....Gear position sensor voltage : 0.28 V
21F671 : Shift lever sensor, voltage below threshold
....ADC voltage Gear lever position sensor channel 1 : 0.06 V
....ADC voltage Gear lever position sensor channel 2 : 0.05 V
....Gear position sensor voltage : 0.74 V
I am no longer getting these errors. My speculation is that previously, when it stopped working, I was continuing to press/pull the foot lever, hoping it would restart. This repeated pressure might have generated some ECU unhappiness. Now, I'm smart enough to stop banging on it. I'm speculating that this is erroneous post-failure data, not a record of the failure itself. But I don't really know. I don't even know if the "ADC voltage gear lever positions sensor channels" are coming from the Shift Assist sensor. Would appreciate any insights from others.

Without any additional ideas, next step will be to replace the sensor. Still debating whether to go for a used OEM ($250 ebay), or a new HM strain gauge Quickshifter ($500) . If I knew for sure that replacing it would fix the problem, I'd easily go for the HM and eliminate the OEM's "squishiness."

Would appreciate any thoughts or opinions.
 

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Discussion Starter · #3 ·
Thanks Benny.

Being a recluse with no friends, borrowing an OEM unit from another bike was not going to work, so I decided to order the HM quickshifter.

Beautiful unit. Looks great. However, one of the best things turned out to be the LCD display used for configuration. Once installed, this enabled me to see that the unit was losing power intermittently.

Turns out I had a broken wire in the bike's harness. Was about 2 inches up from the plug, right where the cable tie secured the harness. My continuity check was flawed as it appears the break only manifested when the cable was flexing.

Cut-Strip-Solder-HeatShrink. Back up and running. HM unit seemed to work great on my road ride last week. Nice and crisp. I'm looking forward to getting it back to the track for a real workout.
 

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Only thing I found that was close to helping me. I need a push button shifter, they user their electronics to do quick shift and blipper. The new Gear Shift Unit, takes all sparks into and send out and blips ignition by having a module from twist grip to ECU.

I am having an issue now where everything works great then the throttle just stops working. Full throttle will give a little RPM, I can reset twist grip adaptation in gs-911 and works for short time then throttle fails again. I get the below errors from gs-911. Guessing my problem is wiring as well as I had to check all wires for voltages so stripped them or tried to stick with a pin.

Any ideas what why BMW keeps stopping my throttle? I have heard this happens when it finds a difference in voltages, just between where and where I do not know.
THANKS
21F952Throttle grip sensor, Channel 1, MIN range error
The fault is currently present.
21F670Shift lever sensor, voltage above threshold
The fault is currently present.
21F672Shift lever sensor, implausible voltage
The fault is not present now.
 

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I had been trying to find the pin-out that OP requested, but could find it nowhere so I ended up finding it through trial and error.

For anyone needing to check continuity from the quickshifter to the ECU, please see the attached image for the pin-out for my 2018 S1000RR.
 

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