Code U1511.00, A/C problem?

PAWEL_N

MEMBER
2016 CADILLAC ESCALADE ESV
6.2L
V8
4WD
AUTOMATIC
50,000 MILES

Hello,
I have a problem with the A/C. It is not working sometimes. Could you please write wiring diagram for all items connected to A/C sensors and LIN BUS? Where is A/C controller/driver? What does it mean U1511.00? When I connected the car to scan tool there was information, that there is not connection to AC/LIN. What shall I check or do? I am waiting for your reply.
Have a nice day,
Pawel

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

The first thing I would do is check the battery voltage which should be 12.4 standing, this guide can help:

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Replace the battery if it fails the test and clear the codes.

U1511: Lost Communication With LAN.

Next, I would check the fuses using this guide:

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

Here is the fuse locations and I have included the AC system wiring diagrams so you can see how the system works, and the sensors involved. Check out the images (below). Please let us know what happens. Please check the fuses with the key on.

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Friday, November 29th, 2024 AT 11:30 AM

PAWEL_N

MEMBER
176 POSTS

Thank you for your reply. I checked all your suggestion and all looks OK.
But I observe more toroubles:
1. One front parking sensor in bumper was not working. Three pcs. Was working, one does not. I replace it and not any in front and not any in rear is working now!
2. The blinds (shutter) in front of cooler is not working (the temperature outside is under 32F).
3. The low range sensor in front bumper is probably not working, because the do not stop in front of an barrier (there is set "stop the car" in menu while barrier in front).
It all looks like a problem with connection in wiring front bumper with some module in car. Where is this module located in car?
What is the wiring in front bumper?
The car is after accident and the front bumper was replaced. I am not sure if all was well fix.

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Monday, December 2nd, 2024 AT 1:25 AM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

I was going some research and the EBCM can be out which might cause these issues. Here is the location of the unit so you can get a preprogrammed unit by searching Google or Ebay. Check out the images (below). Please let us know what happens.

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Monday, December 2nd, 2024 AT 9:54 AM

PAWEL_N

MEMBER
176 POSTS

Thank you for your reply.
1. Is it safe to replace EBCM with other used one? No one sensor in car will lost "memory"? Should I program the new EBCM or should it start working at once?
2. Could you please add wiring diagram between front bumper and EBCM? EBCM have some different connectors. Which one connector (plug) on EBCM goes to front bumper.

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Monday, December 2nd, 2024 AT 11:24 PM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

The replacement BCM needs to be programmed before it will work so you can't just plug one in. You can get them preprogrammed if you search google or eBay for a service that does so. Here are the wiring diagrams for the BCM, I would recheck the fuses for the BCM as well. Check out the images (below). Please let us know what happens.

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