Super Cruise / Adaptive Cruise Control Issue

[DmaxDenaliXL]

Our 2023 Yukon XL Denali with 3.0L diesel with 35,000 miles has been having an ongoing issue that our local dealer cannot seem to diagnose and fix. It is now in the shop for the 5th time for the same issue.

As we are driving down the road with super cruise or adaptive cruise control on, it will randomly throw a warning symbol on the dash, disengage, and say "forward collision system unavailable". With super cruise on, it hits the brakes and starts slowing down for no reason at all. It happens intermittently under all conditions. (Sunny, cloudy, night, interstate, and 2-lane roads) We may drive 50-75 miles without any hiccups followed by the issue happening back-to-back repeatedly.

I think it has something to do with the front facing camera, or the wiring connecting to it (broken/loose wire), but don't have any evidence or knowledge. We didn't notice it happening until around 30,000 miles which is about the same time that the front grill was replaced under warranty. (The "chrome" had cracked and started peeling.) The dealer sees lots of codes and has tried updating and reprogramming and recalibrating it. They've replaced some equipment (but I'm not sure exactly what).

I'm hoping the video below will look familiar to someone who has been through this or has advice I can take to the dealer to get this resolved once and for all. Skip ahead to about 30 seconds to see the first time it has the issue. It then comes and goes several times throughout the rest of the video.

 

[01Konvict]

I have a 2024 escalade and mine has done something similar but at random times. Think total of 5-6 times. Using super cruise with no cars on the highway. Zero for 1-2 miles in front of me. All sudden says forward collision slams brakes and disabled super cruise. I have to pull over turn car off open driver door. Start car and drive down the road 5-10 minutes then it clears and I can use super cruise again. I haven’t gotten a resolution from the dealer yet but will update when I do learn something.

 

[jfoj]

@DmaxDenaliXL

A few comments, some relavent, some maybe not.

I watched the video, see that you are driving during the daytime and following a truck or van with a flat rear window(s). Noticed some lighting flare on the camera, could be because you were holding it, but I would quesiton if the upper camera behind he rear view mirror may be getting sun over exposure from reflections and cutting out?? Have you had similar problems when the sun is not so bright, overcast days, evenings or while driving in the dark?

Next thing I would do just because is have the battery tested. While the Voltmeter appears stable, a questionable battery can cause all sorts of strange problems with all the computers in these vehicles. If for some reason the battery/charging Voltage is not stable, many modules are programmed to drop off line as a means of triage to allow the vehicle to continue to run. Also be aware that these vehicles have Adaptive Charging Systems (GM has used this for over 20 years) where the alternator actually turns off for periods of time and the vehicle will run only on the battery for periods of time and can run the battery to as low as 12.2 Volts before the alternator turns back on. If the the battery is questionable, this could be part of the problem. Unsure if the charging meter in the newer trucks is buffered to mask this behavior, I know my 2005 Yukon the charging meter was not buffered.

On a side note, a bit worried about your oil pressure while cruising. While I do not have a Diesel, I have been monitoring the oil pressure in my 6.2l with some outboard tools and find that while cruising my day indicator tends to be higher than what yours is indicating.

You might want to see if your oil is fuel diluted or if you can get your hands on tool that can display the oil pressure in a numeric value and compare it to other Diesels. To me it looks to be in the 25-30 PSI range based on the dash indicator which for highway cruising may be a bit lower than I would expect.

I have no benchmark or data for the 3.0l Diesel, below is an example of the 6.2l oil pressure vs vehicle speed. The graph was for about a 1 1/2 drive with a some surface street beginning, midway and the end of the graph. The midway point may have had some idling at stop lights moreso than the beginning and end of the graph. While cruising at highway speeds the oil pressue was in the 50 psi range on the 6.2l gasoline engine and as I recall the oil pressure indicator on the dash is beyond the oil handle on the left of the icon, getting closer to the center of the gauge line which would be 60 PSI. The oil pressure spikes are normal, I believe the earlier spikes are the 2 stage oil pump self test, while the 85 PSI spike was when the engine RPM was about 3500 RPM when I was moving around some slow traffic. This is a characteristic of the 6.2l with the 2 stage oil pump.

 

[DmaxDenaliXL]

@jfoj
Thanks for the input. I called the shop and passed along the advice regarding the electrical system. It will be back in the shop Monday again. We picked it up yesterday and it had the same issue again today.

Regarding the oil pressure, I think that is just the nature of the 3.0L diesel, the 0W20 oil, and the variable displacement oil pump. From what I gleaned from this forum and a few others, this engine seems to run at a low pressure.

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