TCM not communicating with PCM

[MarcsM]

merry xmas and a happy holidays.

I have an issue since last week. my jeep wont start. does not crank over. it does have power. radio works, windows work, horn works, lights work. i purchased a new battery. still same problem. i returned the battery and purchased another new battery and still same problem. i put on scanner and got a few codes tcm not communicating with pcm. my question is were exactly is the tcm on this jeep? im pulling my hairs trying to find the tcm. i would like to trouble shoot the harness.
this jeep does not come equipped with the smaller axillary battery under fuse box. kindly if any one know were the tcm is located please shed some light ty
i have the 2018 jeep wrangler jl sahara 2.0l automatic

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[CaJLMetalHead]

can you post the exact codes with their description?

 

[MarcsM]

I appreciate any help I can get. Ty

 

[MarcsM]

From my dash.

 

[CaJLMetalHead]

holy crap.. that is a lot of error messages..

Have you checked the ground connections?.. mine is a 2018 3.6 so I don't know exactly where the ground connections under the hood are for your 2.0... but one thing I know is that if the negative terminals attached to the body under the hood are not making good connections then the computers go haywire...

I will for those errors on my service manual... unfortunately I have the manual for the 3.6L so I don't know how many of those error messages I will find.. but I will do my best..

 

[MarcsM]

I found 3 locations under hood by battery on chasis. Sand them down really good clean and put back together. No fix. I read a thread that there a ground on transmission but I can't located. Not sure we're to look.

 

[MarcsM]

I did check relays and fuse. Also made sure the are seated correctly.

 

[CaJLMetalHead]

 

[CaJLMetalHead]

Are you handy with tools and good with troubleshooting electrical problems ?

 

[Dyolfknip74]

Any chance you had a mouse or critter chew a harness? That's a lot of codes to pop up all at once.

 

[MarcsM]

I done most of my repairs. On all my vehicles. But when it comes to Electrical I'm a little iffy. I'm a barn yard mechanic. I will try my best and then some. After that it will have to go to a shop. Thanks for the reply

 

[CaJLMetalHead]

my JLU 3.6L has tree CANBus ... IHS, C.. and a private CANBus for communication between engine, transmission and I guess other powertrain components... it seems this private CANBus is in bad shape... OR... the actual TCM - Transmission Control Module is bad.. it seems most errors are pointing to the TCM... which is inside the Transmission ..

I wonder what happens if you disconnect the connector from the transmission... what kind of errors do you get.. perhaps some errors will go away and new ones will appear..

 

[CaJLMetalHead]

I done most of my repairs. On all my vehicles. But when it comes to Electrical I'm a little iffy. I'm a barn yard mechanic. I will try my best and then some. After that it will have to go to a shop. Thanks for the reply

DO you have a service manual?...

if not.. then I highly recommend a subscription to:

https://my.alldata.com/

I have a 3-year subscription .. I think is mandatory to have if you are planning on working / fixing issues with your JL.. Alldata is the best service manual for JLs..

 

[Barney392]

Believe it or not the TCM is inside the transmission!

 

[MarcsM]

No wonder I couldn't find the tcm. It's inside the transmission? Huh. I will disconnect transmission. And rescan . As suggested. Thanks for your help

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