Codes P0856, P2544, P150C and U0073, no communication with control modules?

Tiny
SUHAILKADER
  • MEMBER
  • 2015 CADILLAC ESCALADE
  • 6.2L
  • V8
  • 4WD
  • AUTOMATIC
  • 45,700 MILES
Traction and engine light on. RPM needle fluctuating. DTC are- P0856, P2544, P150C, and U0073. Sometimes there is no communication with ECM, TCCM, and TCM when connecting OBD scanner. I checked the CAN H. 60 ohm at pin 6, 14 at dlc terminal. Checked the continuity between CAN H blue and white wires. Is there any possibility of faulty control modules? If so, please give me a method to find out.
Tuesday, March 5th, 2024 AT 2:53 PM

6 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,642 POSTS
The method to check the modules is difficult but it sounds like the TCM has gone out, but I would start by having the system on and checking all fuses. This guide can help and I have included the fuses location as well in the images below. Under the hood and on the left and right sides of the dash.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

P0856: This code is related to the Traction Control Input Signal. P0856: This code is related to the Traction Control Input Signal.

P2544: This code represents "Torque Management Request Input Signal 'A'." It is generally associated with the transmission control module.

P150C: This code is less common and might vary by vehicle and manufacturer. However, in many cases, it relates to the vehicle's speed control or throttle system.

U0073: This is a network communication code indicating that there is a problem with the communication among the vehicle's Control Module Communication Bus "A" Off.

Here is how to test the TCM if you want to give it a try, if not you can send the TCM for testing. Here is the location of the TCM as well. Check out the images (below). Please upload pictures or videos in your response of the problem so we can see what's going on.
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Wednesday, March 6th, 2024 AT 9:33 AM
Tiny
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This car does not have a TCM in the front engine hood. I think it's built in the transmission. Correct me if I'm wrong. If it's built in, how can I check the TCM?
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Wednesday, March 6th, 2024 AT 10:14 AM
Tiny
KEN L
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Is this a 8 speed or 6 speed transmission? Ths 6 speed module is located inside the transmission. Here is how to change the module for the 6 speed unit with the adaptation reset as well. Check out the images (below). Please let us know what happens.
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Wednesday, March 6th, 2024 AT 10:46 AM
Tiny
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Thank you so much for the reply. It is an 8-speed transmission. If the Transmission module is gone out, does that make the CAN bus A off.
If you have transmission connector end view, please share it with me.
Thank you
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Wednesday, March 6th, 2024 AT 12:56 PM
Tiny
KEN L
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Yep, the TCM is part of the CAN and if not working it will cause a communication code. Sure, here is the TCM connector view and identifications and positions. Check out the images (below). Please let us know what happens.
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Wednesday, March 6th, 2024 AT 1:40 PM
Tiny
KEN L
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Anything?
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Saturday, May 11th, 2024 AT 12:00 PM

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