New PCM part no. for 2021 3.6L?

[ShadowsPapa]

I still do not see how the aux kit ties into the PCM. Other than one tap into the BCM LIN Bus, the rest seems to be power and ground hookup to the PDC.

Agreed. The PCM would seem to have noting to do with the body electrics. Something is amiss here. Isn't the programming done via BCM - meaning no impact on the PCM even for programming?
OR am I not understanding this correctly?

The switches get power from the PDC - correct? (and ground), and the BCM settings handle whether or not the switches are hot or switched via ACC and so on?

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[DAVECS1]

Yeah their is no way, they only have communication lines between the two if connected correctly

 

[Hootbro]

Attached the OEM diagram for a 2020 factory install. I assume the kit mirrors this.

Do not know why they would change it for a mid year 2021 with the PCM change as claimed?

As an engineer myself I would think FCA has a process to roll changes like this with their MOPAR department having buy off on the change to drive their kit changes and part number rolls if the Aux kit has changed effectivity.

 

[ShadowsPapa]

Attached the OEM diagram for a 2020 factory install. I assume the kit mirrors this.

Do not know why they would change it for a mid year 2021 with the PCM change as claimed?

As an engineer myself I would think FCA has a process to roll changes like this with their MOPAR department having buy off on the change to drive their kit changes and part number rolls if the Aux kit has changed effectivity.

Change control and versioning and QA and buy-off are your friends?
Man, I recall what had to happen when I was at Compressor Controls. Records records records and every employee had to know the process (even if all you did was answer phones) and where to find the records and who was what part of each process. ISO company.

 

[Lukasz]

Change control and versioning and QA and buy-off are your friends?
Man, I recall what had to happen when I was at Compressor Controls. Records records records and every employee had to know the process (even if all you did was answer phones) and where to find the records and who was what part of each process. ISO company.

I am not an engineer myself. All I can say is that my truck spent six weeks in the shop and that they weren’t able to get it out of limp mode until the PCM was replaced.

They also told me they weren’t able to clear the codes until the aux switch was disconnected.

What I don’t understand is:

1. Why Jeep changed the PCM mid model year with a completely different layout and connectors. I’ve seen other 2021 JTs on dealer lots with the old PCM.

2. Why Jeep’s part catalog returned the wrong PCM part no. for my VIN. It took multiple emails over multiple days between the dealership and Chrysler engineers to figure out what part no. to order.

3. How come that you can buy a vehicle with factory-installed accessories (the aux switch, but also proximity entry, and others), but you can’t add the same accessories to the same model year.

 

[DAVECS1]

I am not an engineer myself. All I can say is that my truck spent six weeks in the shop and that they weren’t able to get it out of limp mode until the PCM was replaced.

They also told me they weren’t able to clear the codes until the aux switch was disconnected.

What I don’t understand is:

1. Why Jeep changed the PCM mid model year with a completely different layout and connectors. I’ve seen other 2021 JTs on dealer lots with the old PCM.

2. Why Jeep’s part catalog returned the wrong PCM part no. for my VIN. It took multiple emails over multiple days between the dealership and Chrysler engineers to figure out what part no. to order.

3. How come that you can buy a vehicle with factory-installed accessories (the aux switch, but also proximity entry, and others), but you can’t add the same accessories to the same model year.

1. They did it and it has not been sone cleanly, your not the only person to be caught out on this sloppy parts change. There is a guy on the site who has a supercharger kit installed and there is no support for the new PCM.
2. As I said in number 1. Jeep has done this swap very messily. If you look through the sites that show you the stock parts when you enter your VIN, it shows the old ECM.
3. Your ECM should support AUX switches, my best guess is they got installed incorrectly, it set off error codes, and there is lack of aervice tool support for the new PCM, so the only recourse was to replace it.

 

[Hootbro]

3. Your ECM should support AUX switches, my best guess is they got installed incorrectly, it set off error codes, and there is lack of aervice tool support for the new PCM, so the only recourse was to replace it.

I agree with this statement. I do not think there is a problem with the AUX kit itself, just a faulty installation revealed a different issue on parts cataloging the new PCM and correct effectivity.

OP cannot be the first and only person with the new PCM and installing the AUX kit.

 

[ShadowsPapa]

Parts listings and "books" are a different topic and handled by different "groups" in most organizations.
I have fought this sort of thing for years. Try to buy front hub bearings for an AMC Eagle...... you'll get the wrong bearing/race set - from almost anyone you buy from.
Why? Because Timken had it wrong. It's fixed now according to the guy there I talked to - but because they had the master list everyone else went by..........
Same for TF selector shaft seals. Only NAPA had it right, all others were wrong because it was wrong in the master list somewhere. I think I got that one corrected as well. Go to buy that seal and you ended up with an extension housing output seal.

 

[Lukasz]

I agree with this statement. I do not think there is a problem with the AUX kit itself, just a faulty installation revealed a different issue on parts cataloging the new PCM and correct effectivity.

OP cannot be the first and only person with the new PCM and installing the AUX kit.

You’re most likely right. I didn’t want to risk going through the whole ordeal again, so I returned the Mopar Aux Switch and ended up getting an aftermarket one.

Chrysler won’t even install the Mopar switch on 2021 and 2022 JTs as it’s only listed as compatible with 2020 model year.

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