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Discussion Starter #1 (Edited)
Quite surprised at how a software update can change the feel of my vehicle for the better.

I brought my 2018 Compass Trailhawk in for routine service and for two concerns (rain sensor and start/stop system inop) which resulted in the update of my PCM (powertrain control module), TCM (transmission control module), and BCM (body control module) as follows:

Old PCM version: 683774457AB
New PCM version: 68377457AF

Old BCM version: P552L3NA300-07-28603540-2903
New BCM version: P552L3NA300-07-28686291-2D02

The TCM was also updated if the proper PCM update repair procedure was followed. Version is not noted on the documents.

After the update, the car's acceleration and gear selection logic significantly improved. The effect is particularly appreciated on cold starts. I noticed merging on freeways is a significantly better experience. It does not feel like a totally different engine — it's still underpowered — but it feels way better to drive.

I learned this week the NHTSA now publishes service bulletins (TSBs) for public viewing. I downloaded a few TSBs from this location:


Relevant TSBs mentioning PCM changes include:

  • November 2, 2019 TSB 18-091-19, Flash: Powertrain Control Module (PCM) Updates, various trouble codes in North America models
  • October 26, 2019 TSB 18-080-19, Flash: Powertrain Control Module (PCM) Updates, excessive engine oil consumption in Latin American models
The TSBs also indicate the TCM (transmission control module) much be updated to the latest software when the PCM is updated. There are a few TSBs for the TCM as well:

  • May 9, 2019 TSB 21-024-19, Flash: Transmission Control Module (TCM) Update, "Customer may notice poor shift quality before engine/trans has reached normal operating temperature"
  • May 31, 2019 TSB 21-030-19, Flash: Transmission Control Module (TCM) Updates, "A bump feeling and high engine RPMs." among other issues
I suspect the November 2 software includes changes published in previous PCM/TCM updates for other markets and unpublished and unspecified changes. The end result isn't directly mentioned in these TSBs. However, I am interested in the engine oil consumption improvement because my engine does consume oil. I did not notice any TSBs referencing BCM changes.

These updates did not fix my start/stop problem (PCM) or rain sensor problem (BCM). However, the tech told me the start/stop system may take several days to work again after the reflash. The rain sensor issue was claimed to be a fault of my aftermarket glass. I disabled the auto sense feature and I have intermittent wipers which is just fine until I inevitably need new glass.

It may be worthwhile to have your Compass taken in for updates if you haven't been since mid November. I'm going back in soon for a Uconnect update which is only available to dealers.
 
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