So you should review page 5 of the Service Bulletin in the first link below, while not specfically for the 10L80 or your model, it pretty well outlines what to do for the code you are getting. Seems that the valve body would need to be replaced. Be careful reading the bulletin as the paragraphs indicate and reference codes "above". The paragraph you need to read is on the right side of page 5.
The 2nd link below has a good coverage about the overall issues with the 10L80E, but there is a part specific to the P187E as well.
While the transmission was replaced, it was likely a "factory remanufacturered" unit. The issue is GM is having MASSIVE valve body problems with the 10 speed transmission. I expect a recall for the same rear wheel lock up to be released for the gasoline trucks and SUVs soon. The recall is really not a "fix", it is a TCM software flash to put the vehicle in "limp mode" to keep the transmission from shifting above a certain gear to prevent rear wheel lock up once a specific trouble code is detected. There was just a recall for this software TCM update released for 90,000 Cadillacs and Camero's with the 10L80 transmisson a few weeks ago. This recall is only for the TCM flash, but as part of this recall, GM is extending the valve body warranty for 15 years, 150,000 miles. See 2nd link below.
In the short term, I would highly recommend ALWAYS using the parking brake until this problem has resolved.
The main problem at the moment is valve bodies are not available. There have been vehicles sitting for over a month waiting on valve bodies.
If it was me, I would likely just get a NextGen valve body kit and either DIY or have a local shop put this in. Even if the current issue is fixed, hard to say if you would not have other problems in the future due the valve body internal leakage issues and wear problems that the NextGen Valve body kit address. It would hopefully fix the problem, but while the valve body is out the valves, sensors and wiring can be inspected for problems and addressed as needed. See 3rd link below.
There could be a wildcard issue here as well. Apparently there are a few different valve body options with and without a default solenoid and with and without electronic shifting. The without default solenoid is for earlier years 2018-2019, not sure this would apply here and what the solenoid was for. But the difference between electronic shifter and mechanical shifter could possible be an issue here? I do not know all the ins and outs about the differences, but there are differences. Possibly the wrong transmission was ordered or the wrong valve body was put in the transmission? These are just things to think about. I am not really impressed with the OE rebuilt transmissions as I do not think valve bodies are really reworked and tested like they should be. This may change with the rear wheel lock up problems, but maybe not?
Good luck and let us know what you do and what happens.
Service Bulletin 21-NA-169
10L80E Info
Valve Body Bulletin
Post with info about NextGen Valve Body Kit
The 2nd link below has a good coverage about the overall issues with the 10L80E, but there is a part specific to the P187E as well.
While the transmission was replaced, it was likely a "factory remanufacturered" unit. The issue is GM is having MASSIVE valve body problems with the 10 speed transmission. I expect a recall for the same rear wheel lock up to be released for the gasoline trucks and SUVs soon. The recall is really not a "fix", it is a TCM software flash to put the vehicle in "limp mode" to keep the transmission from shifting above a certain gear to prevent rear wheel lock up once a specific trouble code is detected. There was just a recall for this software TCM update released for 90,000 Cadillacs and Camero's with the 10L80 transmisson a few weeks ago. This recall is only for the TCM flash, but as part of this recall, GM is extending the valve body warranty for 15 years, 150,000 miles. See 2nd link below.
In the short term, I would highly recommend ALWAYS using the parking brake until this problem has resolved.
The main problem at the moment is valve bodies are not available. There have been vehicles sitting for over a month waiting on valve bodies.
If it was me, I would likely just get a NextGen valve body kit and either DIY or have a local shop put this in. Even if the current issue is fixed, hard to say if you would not have other problems in the future due the valve body internal leakage issues and wear problems that the NextGen Valve body kit address. It would hopefully fix the problem, but while the valve body is out the valves, sensors and wiring can be inspected for problems and addressed as needed. See 3rd link below.
There could be a wildcard issue here as well. Apparently there are a few different valve body options with and without a default solenoid and with and without electronic shifting. The without default solenoid is for earlier years 2018-2019, not sure this would apply here and what the solenoid was for. But the difference between electronic shifter and mechanical shifter could possible be an issue here? I do not know all the ins and outs about the differences, but there are differences. Possibly the wrong transmission was ordered or the wrong valve body was put in the transmission? These are just things to think about. I am not really impressed with the OE rebuilt transmissions as I do not think valve bodies are really reworked and tested like they should be. This may change with the rear wheel lock up problems, but maybe not?
Good luck and let us know what you do and what happens.
Service Bulletin 21-NA-169
10L80E Info
Valve Body Bulletin
Post with info about NextGen Valve Body Kit
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