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OK everyone the new fix for shift to park is out. The TSB is posted on the right it may finally be the fix but those that have had it happen need to report to NHTSA to start a recall for a defective switch that can leave you stranded File a Vehicle Safety Complaint | Safercar.gov | NHTSA
 

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2021 Chevy Bolt LT
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Holy cow.

That seems complicated, even tho it seems to be just a wiring harness......

So the previous fix of just adding the jumper harness wire insert thing is not enough?

Great.

I did previous fix myself, but I dunno about this one.

I would prob just buy a new shift mechanism and install it.
 

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OK everyone the new fix for shift to park is out. The TSB is posted on the right it may finally be the fix but those that have had it happen need to report to NHTSA to start a recall for a defective switch that can leave you stranded File a Vehicle Safety Complaint | Safercar.gov | NHTSA
I was scheduled to have my 2017 shift to park repaired today, brought the car in and the service manager saw this new update, didn't have the part so now I have to return when they get that part! I hope this is the final fix for this problem because it happens more often than not.
 

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I have the shift to park error come on sporadically but just clicking the shift trigger a few times always fixes it. Is that enough to take my car to the dealership to get it permanently fixed under warranty or do I have to wait until the problem is more permanent and I ended up being stranded?
 

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I fixed mine myself months ago by just buying and adding the extra jumper wiring-harness thingie.
Problem has not returned since, but my faith it will not return is minimal.
 

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I have the shift to park error come on sporadically but just clicking the shift trigger a few times always fixes it. Is that enough to take my car to the dealership to get it permanently fixed under warranty or do I have to wait until the problem is more permanent and I ended up being stranded?
That was enough for me (and I think almost everyone else who's posted about it) to get the dealer to fix it.
 

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it's hilarious... At all this time and multiple fixes, they finally end up doing what some others already did as a DIY fix. Replace the switch!

Those who have done this DIY have not had the problem return. Including myself.

Paid $5 for a new switch from Aliexpress. Took me like 35 minutes to swap out. Better than the logistics of getting the car to the dealer for them just to perform a non-fix.
 

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Replaced the switch only myself and added the extra (probably useless) wiring. I still get shift to park probably 10% of the time. But my STP happens when I try to parallel park with lots of D-R shifting. Not sure if it is related. Definitely not related to the switch.
 

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I recently experienced intermittent STP errors at 20K miles on my 2019 LT.

The evolution of this problem through GM's service bulletins is an interesting one. It's clear that GM eventually discovered that while the problem manifests itself in the STP microswitch, the switch itself is not the root cause of STP. The root cause lies elsewhere in the STP switch circuit, which must be why GM developed the special In-Line Harness with some circuit filtering built-in to prevent higher-than-expected in-rush current from getting to the switch. For this reason, replacing the switch alone will only provide temporary relief from STP until the circuit's high in-rush current damages the switch contacts again and STP reappears. The long-term fix appears to require both a new switch and the In-Line Harness together, as evidenced by the December 2020 service bulletin update.

The need for a new switch is due to the fact that an old switch has already developed the internal contact "build up" that increases the resistance to a level that the BCM no longer sees a valid signal from the switch. The October 2019 service bulletin included the new harness and instructions to "clean" the switch by flicking the shift release button 50 times to get the switch contacts moving against each other to break up the build-up. It would appear that this may not help prevent STP from recurring down the road.

Regarding bending the switch lever for "improved" contact: This may hasten some self-cleaning of the internal switch contacts but this won't likely be a long-term fix due to the nature of the Omron snap-action microswitch. By design, a snap-action switch will instantaneously switch at a specific stroke position without relation to the switch operating speed or operating force. So, activating a snap-action switch with more force or greater speed, again, is not going to improve the electrical performance for the long-term.

Since my STP just showed up within the last week and occurred only 3-4 times, I decided to perform the October 2019 bulletin with the switch "cleaning" procedure and installation of the new In-Line Harness. I did the work in about 20 minutes. I'm going to order the replacement switch to have one handy if the STP crops up again --indicating that my old switch can't "clean" itself enough to make the BCM happy.

As for the December 2020 service bulletin, it's pretty clear that GM knows the In-Line Harness may not resolve the problem for shifter switches that are too far gone. It's even more clear that GM is trying to cut the cost of warranty repairs by instructing the technicians to just replace the STP switch harness ($25) instead of replacing the entire shift quadrant ($180) as was the standard practice. They must figure that the labor to remove/replace the STP wiring is the cheapest way to get a new switch installed. They also don't want to mess with dealer technicians attempting to desolder/solder switches and possibly damaging the switch, wiring, or worse.

Finally, the service bulletin indicates that vehicles built or repaired prior to April 2, 2019 would have used the older-generation shift quadrant assembly and so they are all susceptible to developing the STP error. We can assume that shift assemblies supplied after April 2019 include a design change to eliminate the in-rush current problem that can damage the switch.

We'll see how it goes. Interestingly, my 2016 LT never developed the STP error in the 30K miles I had it before I got the 2019.

Still love this car!
 

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I replaced the switch and added the in-line harness and never had STP as described. However I am still occasionally getting STP and engine stop while trying to parallel park, shifting between D-R. Micro switch and solenoid should be out of the question so not sure what other part is failing this time.
 

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I still have to say the real problem is how far the switch is being pushed by the metal rod on the shifter. If I remember, you can see this by just removing the shifter boot. I don't think there's anything special about the switch but when the bar and switch meet it's almost on a hairline for activating the switch. The switch just needs to be pushed a bit farther and the easiest way is to increase the diameter of the rod. ( Plug, cap, hose ) it's easy enough to try.
 

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I added the "jump harness" thing myself and the STP went away.....for awhile.
Then I had to take my Volt to the dealer for an inspection, and the shop lackey kid with his gorilla grip
seemed to smash the shifter button so bad that it felt loose when i got my car back......
mad me super mad.
Now the STP is back again on occasion.......
very annoying.....
makes an otherwise nice car feel like delicate junkpile.
 

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And that is?
replace the micro switch only?
 

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It's on a previous post, only thing I did was install a small cap on the shaft that hits the micro switch, could probably use a piece of tubing. Just makes a more solid contact for the switch.
 

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I recently experienced intermittent STP errors at 20K miles on my 2019 LT.

The evolution of this problem through GM's service bulletins is an interesting one. It's clear that GM eventually discovered that while the problem manifests itself in the STP microswitch, the switch itself is not the root cause of STP. The root cause lies elsewhere in the STP switch circuit, which must be why GM developed the special In-Line Harness with some circuit filtering built-in to prevent higher-than-expected in-rush current from getting to the switch. For this reason, replacing the switch alone will only provide temporary relief from STP until the circuit's high in-rush current damages the switch contacts again and STP reappears. The long-term fix appears to require both a new switch and the In-Line Harness together, as evidenced by the December 2020 service bulletin update.

The need for a new switch is due to the fact that an old switch has already developed the internal contact "build up" that increases the resistance to a level that the BCM no longer sees a valid signal from the switch. The October 2019 service bulletin included the new harness and instructions to "clean" the switch by flicking the shift release button 50 times to get the switch contacts moving against each other to break up the build-up. It would appear that this may not help prevent STP from recurring down the road.

Regarding bending the switch lever for "improved" contact: This may hasten some self-cleaning of the internal switch contacts but this won't likely be a long-term fix due to the nature of the Omron snap-action microswitch. By design, a snap-action switch will instantaneously switch at a specific stroke position without relation to the switch operating speed or operating force. So, activating a snap-action switch with more force or greater speed, again, is not going to improve the electrical performance for the long-term.

Since my STP just showed up within the last week and occurred only 3-4 times, I decided to perform the October 2019 bulletin with the switch "cleaning" procedure and installation of the new In-Line Harness. I did the work in about 20 minutes. I'm going to order the replacement switch to have one handy if the STP crops up again --indicating that my old switch can't "clean" itself enough to make the BCM happy.

As for the December 2020 service bulletin, it's pretty clear that GM knows the In-Line Harness may not resolve the problem for shifter switches that are too far gone. It's even more clear that GM is trying to cut the cost of warranty repairs by instructing the technicians to just replace the STP switch harness ($25) instead of replacing the entire shift quadrant ($180) as was the standard practice. They must figure that the labor to remove/replace the STP wiring is the cheapest way to get a new switch installed. They also don't want to mess with dealer technicians attempting to desolder/solder switches and possibly damaging the switch, wiring, or worse.

Finally, the service bulletin indicates that vehicles built or repaired prior to April 2, 2019 would have used the older-generation shift quadrant assembly and so they are all susceptible to developing the STP error. We can assume that shift assemblies supplied after April 2019 include a design change to eliminate the in-rush current problem that can damage the switch.

We'll see how it goes. Interestingly, my 2016 LT never developed the STP error in the 30K miles I had it before I got the 2019.

Still love this car!
My 2018 LT, which I purchased in March of 2019 has just started to demonstrate the problem.

I gotta wonder how anyone is going to do all of that in the allotted 1.1 hours!?

I'll have to call the dealer tomorrow. I presume that this is still the most current TSB to reference (or if not, it'll be a revision, rather than new TSB number)?
 

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I just got this fixed at my local Chevrolet. This is the third time I’ve taken it in for the same problem. The first two times they claimed they didn’t know what the issue was. Today, the person said it’s a well known problem. Needless to say, Chevrolet has been a pain to deal with.
Anyway, I wanted to point out that the fix was free because the 2017 Volt was still under an “electric car” warranty. The problem was what others have stated: shift control button was stuck. Replaced shift control assembly and installed harness as per doc#5403533

See attached pic for copy of their explanation. Don’t let them charge you for this fix!



OK everyone the new fix for shift to park is out. The TSB is posted on the right it may finally be the fix but those that have had it happen need to report to NHTSA to start a recall for a defective switch that can leave you stranded File a Vehicle Safety Complaint | Safercar.gov | NHTSA
C225A5A4-8FE8-463C-B869-B18FC00EAF27.jpeg
 

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Hence, one of the many reasons I sold my 2018 Volt and got a 2021 Bolt.......
 

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Should I be worried? I'm not sure if this recall was ever done on mine. But I'm not having any issue. Is this VIN specific or ALL ?
 

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Should I be worried? I'm not sure if this recall was ever done on mine. But I'm not having any issue. Is this VIN specific or ALL ?
That's not REALLY the problem the service bulletin was issued to fix, but that dealership decided the wording was close enough. Shift buttons break, but it's rare because they're known and tested things and normally pretty easy to overengineer.
 
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