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Shift Assist problem and repair

MCMXCIVRS

More toys than space
Last month on the first day out for a 3-4 week tour the quickshifter on my F850GSA quit working. I had along my GS911 tool and so that night in the campgound I checked for codes and found a number of codes relating to the quickshifter sensor. I cleared the codes and hoped maybe the problem would sort itself, but as soon as I set off the following morning the problem was still present. So, for the next 8000 kms on the trip up to the Yukon and Alaska I had to shift old school using the clutch. How barbaric.

After completing the trip and having some time to look into the problem at home. I checked for codes again and came up with four related to the quickshifter; 0x3A1193 - Shift lever sensor erroneous voltage, 0x3A1195 - Shift lever sensor, faulty voltage level 2, 0x3A1190 - Shift lever sensor voltage above threshold, and 0x3A1192 - Shift lever sensor implausible voltage. With a little online searching, I found a few discussions on various forums that described similar failures as mine with the same types of codes set. None referred to the F model bikes specifically, but the problem was almost universally that of broken wires near the shift lever sensor. With that information I started checking the wires at the sensor where others had reported breakage and found no issue. So I opened up the sleeve loom on the wiring to check further up the wires and sure enough, two of the four wires were broken in the same spot. I did a quick solder repair of the two wires and that had the issue solved - at least so far as making the Shift Assist work again.

My concern however was that the reason for the wires breaking was that they were too stiff given the flexing they need to do as the shifter is operated and secondly the way the wires were routed they basically made a sharp bending action at the point they were anchored near the sensor. That was the exact location that both wires had broken. To make the situation worse, the repair soldering of the wires made them even stiffer at that spot. I figured that it was doomed to fail again at some point in time, so I began to work out a better repair.

Initially, I started by sourcing some silicone insulated flexible wiring in 24ga. thinking I would just splice in a section between the main harness and the connector plug. But as my mind worked further on the problem, I decided I didn't want to have multiple splices in the wiring and started to see if I could find the correct terminals to fit the connector plug so I could replace the full length of the wires with just a single splice to the harness. After going through pages of possible terminal online at Digikey, I finally found the exact right ones, and ordered up a small lot of them for a pretty reasonable cost. I also lacked the correct crimpers for the terminals so I had to source a pair of those as well, I had ones in the correct style, but not of the correct size for these smaller gauge wires. The rest of the needed items were on hand in my collection of wiring supplies. This included heat shrink tubing and flexible woven wire loom.

With all the material on hand I was able to easily make up a new pigtail using the original connector plug and new terminals and the flexible wires. I used the more flexible braided loom for the end of the pigtail where it needs to flex to allow for the movement of the sensor with the shift lever. I left the new pigtail a couple inches longer than the original wires when I spliced them into the harness wires. This allowed the wires to make a larger loop at the sensor to eliminate the sharp bending action on the wires. I added a small zip tie onto the harness above the point where it exited the existing clamp point to redirect the wires at 90 degrees upward then looping down to the sensor. this longer loop allows much smoother flexing of the wires which coupled with the added flexibility of the wires and loom should prevent this from being an ongoing issue.

Original routing showing breakage location
Wire original bend.jpg

wire terminal
Connector terminal.jpg

opening up the connector
Connector.jpg

New wires
New pigtail.jpg

New pigtail completed
Pigtail completed.jpg

Splicing pigtail onto the harness
Spliced onto harness.jpg

completed repair with more flexible longer loop
Completed repair with longer loop.jpg
 
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I haven't done that yet, but will do so after completing the next order of work on the bike this week which is the overdue full 40K km service. I'll need to reset the reminders with the GS911 after, so will do all of the functions then.

As an addition, I just saw on another forum that someone had the same problem and apparently BMW has a service repair that is essentially a longer wire pigtail and a stiffener to prevent the wires from bending sharply. Probably costs more than my fix though.
 
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