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Discussion Starter · #1 · (Edited)
A little over a month ago, I made a video showing how I adjusted the springs inside the shifter in an attempt to fix the shift to park issue. It seemed to help a little, but it did not last. So I was determined to find a true, lasting fix or a workaround.

Since then, I believe I have found a solution. Ive been testing it now for a little over 3 weeks, and I've had zero 'shift to park' displayed, nor have I found any other adverse side effects, (although a few positive ones.)

I removed the shifter from the car, which involved partially removing the center console. Once removed, I found that the shifter release button activates one sensor mounted on the side of the shifter.
10138


It's really the only positional sensor in all of the shifter assembly. And since GM is replacing the entire shifter, and I haven't heard any talk of them peering into the actual transmission, it's really the only possible culprit.

Micro switch is labeled "omron aq l251 1186 nz "
I spent a few hours just trying to find a replacement micro switch, but they are literally hundreds of thousands to choose from. I found a quite a few sites that let you sort by different options, but still I could not find any. I suppose I may call the manufacturer directly to inquire, this might be the best option.

The fix
So the micro switch has two wires going to it, a blue wire, and a black ground wire. When out of gear, the switch is open, when in park and the release button disengaged, the switch gets shorted to ground.
These colors change at the harness connector, to black and purple with white stripe.

I simply shorted the switch at the plug to ground all the time to see what would happen.
10139


Like I mentioned earlier, our Acadia is driven a few times every day, and for the past 3 weeks I have not had a shift to park air at all. I also have had zero ill effects from the switch being shorted to ground. Everything, lights, navigation, seems to work exactly as it did before with one exception. The navigation is now unlocked. Meaning we can put in addresses while driving, I don't remember being able to do that before.
I'm hoping a few others are able to try this, and test it out to make sure there are no errors in their cars as well.

Anyway, the only drawback I see, is it's kind of a pain in the butt to get to the plug. It requires moving the center console back a few inches so you can get the upper cup holder bezel removed.
It sounds harder than it is, the short of it is to remove both side panels which are just one 7 mm screw each, and a few snaps,
then remove the 12 10 mm bolts that hold the center console into place.
simply slide the center console back approximately 3 in, and that will allow you to lift up the cup holder bezel, giving you access to the plug.

From there, simply remove the plug, install a jumper as pictured above. And then reinstall. Hope this works for you guys as it has for me

10140
10142




Edit, here is the video, start to finish
 

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A little over a month ago, I made a video showing how I adjusted the springs inside the shifter in an attempt to fix the shift to park issue. It seemed to help a little, but it did not last. So I was determined to find a true, lasting fix or a workaround.

Since then, I believe I have found a solution. Ive been testing it now for a little over 3 weeks, and I've had zero 'shift to park' displayed, nor have I found any other adverse side effects, (although a few positive ones.)

I removed the shifter from the car, which involved partially removing the center console. Once removed, I found that the shifter release button activates one sensor mounted on the side of the shifter.
View attachment 10138

It's really the only positional sensor in all of the shifter assembly. And since GM is replacing the entire shifter, and I haven't heard any talk of them peering into the actual transmission, it's really the only possible culprit.

Micro switch is labeled "omron aq l251 1186 nz "
I spent a few hours just trying to find a replacement micro switch, but they are literally hundreds of thousands to choose from. I found a quite a few sites that let you sort by different options, but still I could not find any. I suppose I may call the manufacturer directly to inquire, this might be the best option.

The fix
So the micro switch has two wires going to it, a blue wire, and a black ground wire. When out of gear, the switch is open, when in park and the release button disengaged, the switch gets shorted to ground.
These colors change at the harness connector, to black and purple with white stripe.

I simply shorted the switch at the plug to ground all the time to see what would happen.


Like I mentioned earlier, our Acadia is driven a few times every day, and for the past 3 weeks I have not had a shift to park air at all. I also have had zero ill effects from the switch being shorted to ground. Everything, lights, navigation, seems to work exactly as it did before with one exception. The navigation is now unlocked. Meaning we can put in addresses while driving, I don't remember being able to do that before.
I'm hoping a few others are able to try this, and test it out to make sure there are no errors in their cars as well.

Anyway, the only drawback I see, is it's kind of a pain in the butt to get to the plug. It requires moving the center console back a few inches so you can get the upper cup holder bezel removed.
It sounds harder than it is, the short of it is to remove both side panels which are just one 7 mm screw each, and a few snaps,
then remove the 12 10 mm bolts that hold the center console into place.
simply slide the center console back approximately 3 in, and that will allow you to lift up the cup holder bezel, giving you access to the plug.


From there, simply remove the plug, install a jumper as pictured above. And then reinstall. Hope this works for you guys as it has for me
Thanks for your investigation of this.
I have said for months now the GM should look at replacing the micro switch with a more durable and stout one.
Your test has seem to reveal and verify my supposition .

If this ever happens to our 2019 Acadia, I am of a mind to source a better switch. It was good to see you list the Omron switch number Omron makes many such micro switches and now with that model number, the size and volt/amp rating can be referenced to find, perhaps a better switch. Or, at least a more durable and reliably way of repairing this common issue.

Thanks so much for your efforts and documenting this.
 
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Micro switch
The fix
So the micro switch has two wires going to it, a blue wire, and a black ground wire. When out of gear, the switch is open, when in park and the release button disengaged, the switch gets shorted to ground.
These colors change at the harness connector, to black and purple with white stripe.

I simply shorted the switch at the plug to ground all the time to see what would happen.
I'm hoping a few others are able to try this, and test it out to make sure there are no errors in their cars as well.
Another temporary jumper point might be to use a micro clip test lead to jumper the switch right at it's connections. If that is easier to get at.
I saw a few threads on the Mailbu forum where they too have had the "Shift To Park" issue and the whole shifter can be removed to work on it. Not sure if you tried that?

Anyway. . here is the points where the soldered connections (red arrows) that could be jumpered with a micro test lead and clips. Also a link for test clips as an example . - - Min Test Lead Clips

The test lead clips can be found from many sources, I post the ones in the link so others can look at the pictures and see the small hook clip that can be attached to small connection points like the micro switch in the shifter.
Wire Electrical wiring Auto part Bumper Technology Tool accessory Tool
 

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I was poking around on Digikey and , of course, they have a large selection of micro switches.
While not sure of the dimensions of the one in the shifter . . . here is a list of some plus one that would be really robust rated at 10A/250V and 50,000 cycles. There are many others of 5A/125V of 3A/250V and 200,000 cycles.
Anyway. . not enough time to go through and find an exact fit by just guessing the size of the switch.
But I suspect the vendor for the shifter . . . selected a switch with only 200 to 300ma current rating and not very robust. With micro switches. . . I've always found to go well above the operating parameter for current and voltage.

 

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Another temporary jumper point might be to use a micro clip test lead to jumper the switch right at it's connections. If that is easier to get at.
I saw a few threads on the Mailbu forum where they too have had the "Shift To Park" issue and the whole shifter can be removed to work on it. Not sure if you tried that?

Anyway. . here is the points where the soldered connections (red arrows) that could be jumpered with a micro test lead and clips.
I still dont think you could access the mirco switch from the side or the top (with the leather boot removed). its located at the top rear under a snap on cover, and the pug is at the very rear, very low.

I was poking around on Digikey and , of course, they have a large selection of micro switches.
While not sure of the dimensions of the one in the shifter . . . here is a list of some plus one that would be really robust rated at 10A/250V and 50,000 cycles. There are many others of 5A/125V of 3A/250V and 200,000 cycles.
Anyway. . not enough time to go through and find an exact fit by just guessing the size of the switch.
But I suspect the vendor for the shift . . . selected a switch in with only 200 to 300ma current rating and not very robust. With micro switches. . . I've always found to go well above the operating parameter for current and voltage.

I think digikey was the main site i looked on as well. I couldn't find a way to sort by size.
Here is the size of the snap action switch best i could measure:
Text Font Handwriting Finger Design
 

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Any update here? There is no doubt this switch is the culprit. I am unable to find the spec sheet for this exact switch to determine if my hunch is correct. I am an electrical engineer by profession and deal with similar issues frequently on relays and switches that are misapplied which I believe has happened here.

Typically manufacturers will apply AC rated microswitches in DC applications. Perfectly acceptable IF you run rated or close to rated current which is what helps wipe the contacts. The switch in my 2017 Acadia Denali is not completely shorting but is several ohms which tells me the contacts need to be wiped/burnished. This is a small seal switch so it's going to be difficult to do that. I'm going to make a small DC current rig and apply a decent chunk of mA and see if I can get the resistance to drop or go-to full short as it should.
 

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Discussion Starter · #7 ·
I know me and JT looked into it for a little bit, but I've been totally slammed at work and at home with projects. Since my Acadia is working totally fine with the shorted switch, I've kind of put looking for a fix on hiatus.

Maybe we're over complicating things by trying to find a replacement switch, maybe shorting it is good enough lol
What's it been, three months now? I've had zero issues. However if anybody does find a correct switch, please, please post it here!
 

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Any update here? There is no doubt this switch is the culprit. I am unable to find the spec sheet for this exact switch to determine if my hunch is correct. I am an electrical engineer by profession and deal with similar issues frequently on relays and switches that are misapplied which I believe has happened here.

Typically manufacturers will apply AC rated microswitches in DC applications. Perfectly acceptable IF you run rated or close to rated current which is what helps wipe the contacts. The switch in my 2017 Acadia Denali is not completely shorting but is several ohms which tells me the contacts need to be wiped/burnished. This is a small seal switch so it's going to be difficult to do that. I'm going to make a small DC current rig and apply a decent chunk of mA and see if I can get the resistance to drop or go-to full short as it should.
I'll let you know in a few days.
I will be getting a used 2018 Acadia shifter from an associate . . (same GM part number as the replacements).
The shifter did not have the shift to park issue that we know of but is out of a salvage Acadia.
I want to evaluate the switch physical and electrical characteristics. Right now I do have some pictures that at least identify some things.
Auto part Engine Vehicle Machine Automotive engine part
Auto part Wire Technology Vehicle Automotive exterior - - " Click on Image To See Full Size "
 
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I setup a test rig on my bench tonight. I used a wall wart (12VDC outputting 15 VDC open circuit) and came up with resistors sized to output 200 mA. I used the switch to make and break the circuit and operated it about 50 times being sure to pickup full current before breaking the circuit. The resistance of the switch went from 2.6 ohms to .5 ohms. I reinstalled it and will keep an eye on it for awhile and report back either way.
 

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I setup a test rig on my bench tonight. I used a wall wart (12VDC outputting 15 VDC open circuit) and came up with resistors sized to output 200 mA. I used the switch to make and break the circuit and operated it about 50 times being sure to pickup full current before breaking the circuit. The resistance of the switch went from 2.6 ohms to .5 ohms. I reinstalled it and will keep an eye on it for awhile and report back either way.
Good insights and similar to what I will do when I get the salvage shifter.
So you have your Denali shifter apart because of the shift to park message?

I suspected as much that the contacts in the shifter switch are only rated for 200ma to maybe 500ma. I've suspected and said the switch failing to make full contact connection is the problem since reading of this issue and said GM should be specifying a better switch in several past threads. Omron and others make switches of this approximate size with ratings up to 5 amps or so. Although the switch in the shifter seems to be a bit of a mystery as to what the specs may be.

Likewise here I worked in both automotive and some avionics electronics for many years as well as testing platforms for ECMs/PCMs and other electronics. I also have come across what you described earlier about the switch contacts and relay contacts getting oxidized and increasing in contact resistance.

I have a switch and another on order that I want to test which has a larger contact area and may help.

EDIT: I have looked at the previous generation Acadia/Traverse/Enclave shifter and some other GM shifters and they also use a micro switch for signalling the park position and have not had the problems this current Acadia has. However, the switches used in those shifters are a larger more robust physical size, while that Acadia ,Mailbu, etc use this smaller switch.
Wondering if a dose of dielectric grease inside the switch would help keep contacts working better? Or something like Fader lube?
 

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Yes. I tore mine apart to investigate and I'm outside of bumper to bumper. I have 125k extended but honestly don't want to deal with these jokers unless I have to.

I'm digging into this switch. Hopefully I'll come up with something. I'll probably try to get an Omron engineer on the phone Monday and see what I can come up with. I'm betting they can come off some specs.
 

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Yes. I tore mine apart to investigate and I'm outside of bumper to bumper. I have 125k extended but honestly don't want to deal with these jokers unless I have to.

I'm digging into this switch. Hopefully I'll come up with something. I'll probably try to get an Omron engineer on the phone Monday and see what I can come up with. I'm betting they can come off some specs.
Hoping it isn't too late. . . but if you still have the shifter apart, could you measure the actual current draw of the Park Switch circuit when it is closed and sinking to ground? That would tell us if the switch is handling , perhaps, more current draw and arcing than the switch was designed for.
I suppose you could maybe simulate any arcing by checking "make and break" using the jumper you were using and see if there is a sizable vizable arc when that is done.
Also, wondering, if the switch is also handling an inductive load (relay or small solenoid?) rather than just a signal level.
If so, that could wreak havoc with arcing of the contacts.
 

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I still dont think you could access the mirco switch from the side or the top (with the leather boot removed). its located at the top rear under a snap on cover, and the pug is at the very rear, very low.
I setup a test rig on my bench tonight. I used a wall wart (12VDC outputting 15 VDC open circuit) and came up with resistors sized to output 200 mA. I used the switch to make and break the circuit and operated it about 50 times being sure to pickup full current before breaking the circuit. The resistance of the switch went from 2.6 ohms to .5 ohms. I reinstalled it and will keep an eye on it for awhile and report back either way.
Toying a bit with another work around. The factory switch is really an ultra micro switch. Very small and not very robust. Plus it looks like a custom design with mounting posts rather than holes. That could be remedied if a similar switch is found. Anyway, looking at this since it would just be a redundant switch and both would make contact and assure a connection.
 

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Rhetorical question but why hasn't GM re engineered this by now? Can not be cheap to be replacing shifter assemblies not to mention the inconvenience to the owners. What about a magnetic reed switch? Would seem to be rated at more cycles for life expectancy.
 

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There is a TSB on this, so perhaps GM and suppliers are still working on it?
 

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Rhetorical question but why hasn't GM re engineered this by now? Can not be cheap to be replacing shifter assemblies not to mention the inconvenience to the owners. What about a magnetic reed switch? Would seem to be rated at more cycles for life expectancy.
Good question. I think it may be a matter of getting the supplier who designed these shifters and the supplierof the switch itself to ante up and offer a solution. The potential problem exits in other GM vehicles like Traverse, Mailbu, Volt and the 2019 Chevrolet Blazer on some 2016 to 2019 models.
I imagine GM has been wrestling with the supplier on this and typically there might me a lot of back and forth regarding who or how design specs were managed.
A reed switch would be a good idea, but the fact is, all other GM vehicles have been using a micro switch in the shifters for many years.
However, I've looked at the first generation Acadia and some other GM vehicles and the switch used in them is a larger more robust design and has not been problematic. Other car makers use the same and some may even use the same supplier as GM does.
So, to me, it's an issue of the switch design itself which is yet another supplier. That, and the rather small space and compact size of this shifter and resulting space allocated for the ultra small micro switch.

The switch I used in the mock up is rated at +10,000,000 cycles and is typical of many micro switches. The contacts are much larger and therefore, IMO, would offer more durability than the much smaller factory switch and handle any electrical load it may see easily. It is almost 4 times larger than the factory switch in the shifter.
 

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I have had very good luck with mine after a month of use from checking it. Once warm weather returns I will dismantle one more time and operate the switch with a bit more current to properly wipe the contact clean. Like I mentioned before, I have dealt with this in my profession and the amount of current being passed through this switch given the voltage present isn't enough to keep the contact surface burnished.

I have had a handful of times where the warning has been popped up but a couple of full actuations of the shift knob WHILE IN PARK clears it up quickly. This is fixable in my opinion with a little patience and a simple AC/DC wall wart with enough current.
 

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I have had very good luck with mine after a month of use from checking it. Once warm weather returns I will dismantle one more time and operate the switch with a bit more current to properly wipe the contact clean. Like I mentioned before, I have dealt with this in my profession and the amount of current being passed through this switch given the voltage present isn't enough to keep the contact surface burnished.

I have had a handful of times where the warning has been popped up but a couple of full actuations of the shift knob WHILE IN PARK clears it up quickly. This is fixable in my opinion with a little patience and a simple AC/DC wall wart with enough current.
Apologies. .. but are you suggesting to periodically connect up the "wall wart" every time the switch contacts get flakey again? That wouldn't be much better than GM's "solution" of flicking the switch "50 times" as in the TSB in hopes of cleaning the contacts. . . which did not work as a fix BTW.
It would be helpful to know if you did an actually current measurement that the switch is handling.
In the grand scheme of things, I've found automotive wiring documents and data are not always accurate.
There may be more (or less) in the circuit that said diminutive little switch is handling.
There are tiny micro switches in the Logitec M570 Trackball mice I use that likely draw as little or less current than the one in the shifter. They last years longer. I've replaced one left mouse button in one of mine after over 8 years use and many hundreds of hours and a myriad of operations. They just should not fail like this in the shifter.
I'm thinking the issue is the opposite. The switch in the shifter can not handle the current fed through the switch and the contacts are arcing slightly with each operation. So they eventually get burned and oxidized preventing good contact.
Else why the mystery adapter harness the TSB directed to insert between the switch and original wiring connectors?
 
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WOW. Wasn't expecting to spit all that out today. And to top it off, it appears the moderators are reading every post here. Seems odd, but so be it...
Why is that so odd? It's interesting to me given my background in electricity and analog/digital electronics.
 
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