rkawal

I had my 2022 Sierra 3500 HD retrofitted the other day and the Park Assist is a nice feature. However I'm fighting with GM because my truck also has U1D , the Trailering App using the K68 Trailer Lighting Module. In my case, I use a slide in camper mounted in the 8' bed and that turns off the Rear Park Assist. What is happening is that the K68 module is recognizing the camper as a trailer and turns off Rear Park Assist. This would make sense if a trailer was behind the truck, but in my case, the camper is not blocking the rear bumper sensors, so the system should work properly. But I've learned that the K68 module software uses detection of the four lighting circuits (left and right stop/turn, reverse light, and park lights) to detect whether or not I have a trailer. In the Trailering App is an option to choose Accessory - No Trailer, but it doesn't work. The module software needs to be fixed so that when a trailer is not present, rear park assist should work as intended. In my case, rear park assist works perfectly only if I unplug my camper from the truck. Obviously that isn't OK.

I have a really tough problem that I think is going to take a master at body control module logic to figure this one out. It’s not a serious problem but one, as an engineer, I don’t want to give up on. I’ve been pursuing a solution for the last three years, off and on. I’m 73 years old, and I currently have seven vehicles, all GM. Every car I’ve ever owned has been a GM vehicle. My current vehicles range from a 1985 Chevy Silverado K30 to a C6 Corvette Z06 to a 2018 Chevy Volt. But the vehicles I’m trying to figure out are my 2006 GMC Sierra 2500 HD regular cab SLE and my 2005 GMC Yukon Denali. My 2005 Yukon Denali has TPMS (RPO UJ6) built in, and the steering wheel controls allow the DIC on the IPC to show individual tire pressures. I want that feature on my Sierra SLE that does not have UJ6. Being a GMT 800 series vehicle I should be able to add it. I have both GM Service Manuals for each vehicle and both Service Manual describe TPMS, so it was obviously an option on some Sierra pickups. On the Sierra, I installed tire pressure sensors, and I replaced my PDM with one that included TPM, like the Yukons, etc. With my Tech 2, I went into Chassis and enabled TPMS and set each tire pressure to my desired pressure. Individual tire pressures are shown on the Tech 2 as expected. Also, on the IPC the Low Tire Pressure light works normally if it senses a low tire pressure. All is well to that point. TPMS works fine in both vehicles. But the Denali steering wheel controls allow me to press the Odometer button to cycle through the various functions like odometer, trip, timer, hours, etc. – INCLUDING Tires Pressures. I can then press the reset button (lower right) and cycle through each tire pressure, with the pressures showing on the DIC. On the Sierra, pressing the same buttons, the Tire Pressure function is omitted. Upon studying the Service Manuals, in both the Body Control Module and the IPC schematics shows a dotted box named “Logic” as part of the IPC, implying that the logic is in the IPC. But swapping the IPC between vehicles results in the same omission of Tire Pressures in the Sierra. The Sierra IPC shows Tire Pressures in the Yukon, but the Yukon IPC will not show Tire Pressures in the Sierra. So the logic must be elsewhere. When connecting the Tech 2 to the Sierra and uploading information to SPS for the TIS2000 programming, I get a programming option limited to only the PCM/VCM. When doing the same for the Yukon Denali, I get programing options for almost every module in the vehicle. It seems that the BCM for the Sierra might be a “base” model (since it’s only a regular cab SLE) while the BCM in the Yukon seems to have many more features that are programmable. A new BCM for the Sierra is listed as GM p.n. 19369689 while the BCM for the Yukon is p.n. 19369690. I’m GUESSING that the LOGIC shown in the Service Manuals for the IPC is actually in the BCM. If this is true, then could I use the Yukon BCM in my Sierra and obtain my objective? When looking up the GM part numbers, the 19369690 BCM says it is compatible with most every GMT800 vehicle, including Sierras and even Escalades. Is there someone in GM that could confirm that the logic for TPMS is left out of the steering wheel control function for the DIC in the SLE Sierra? Would installing the “uplevel” BCM be my solution?