Strange thing – cadillac xt4 forum gasbuddy app

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here’s the main issue.. wife backs out of the garage and into a turn around area (about a 100 feet) she then puts the vehicle in drive and starts to roll down the driveway which is about a 10 degree slope (relatively steep) because of this she has neither her foot on the brake (yet, but will soon as the vehicle accelerates) nor her foot on the gas.. at this point the vehicle is going at a brisk walk or close to a jogging speed.. the vehicle has just done an up shift, and then immediately after that a downshift, and then it lurches a couple times and brakes itself to a complete stop..

when the vehicle is in this situation (lets call it failure mode) this is what we’ve tried.. setting park brake with park brake switch and then releasing bark brake by pushing brake peddle.. (as the manual says) .. if you give the vehicle any gas it will creep forward but has resistance as though your holding the brake pedal.. the moment you take your foot off the gas the car returns to a complete stop.. now keep in mind the driveway in this location is steep enough that the car should be rolling like crazy.. we’ve also tried pressing the brake peddle firmly a number of times with no result.. the only way the vehicle can be made to "resume normal operation" is to either shift it into either neutral or park and then back into drive and then off you go..

okay so now the good stuff.. the shop foreman is in the car, scanner plugged in and he’s ready for anything.. car goes into failure mode and he see’s nothing on the scanner.. he searches through all the BCM’s and nothing.. so now I put the vehicle into park and the dash displays the park brake symbol as well as the DIC saying "park brake set".. the only problem is the scanner says it isn’t.. it says that the park brake switch is "applied" but non of the park brake components are active.. we tried this a number of times with the same results.. if you applied the park brake yourself by utilizing the park brake switch the system worked as advertised, but if you got the "park brake applied" indication when in the hill assist situation it was in fact not..

they noticed in the video the drivers seatbelt warning lamp illuminated.. this is because about 300 feet down the driveway you need to get out and open a gate.. neither my wife or I can honestly say whether or not this failure mode has happened when wearing the seatbelt.. electricity out in one room GM says the car is breaking to a stop possibly because the driver isn’t wearing their seatbelt.. really?

so now I go to the dealer so they can look at the trans fluid.. gas density units I explain how the park brake made no difference and how popping it into neutral allowed the vehicle to move again.. they look at the trans fluid and don’t really see anything so I jump back into the car and off I go.. about 30 minutes later I get a call from the dealership saying GM is shipping a new transmission and transmission cooler.. they don’t say if they found anything or not but GM decided to replace the transmission.. the interesting thing is they are told that when they install the new trans and cooler to service with fluid, run it for 5 minutes on the hoist and then drain and flush the trans and then service with new fluid.. this has me puzzled.. gas vs diesel truck I don’t know of any other system that could be contaminated by the trans so why the run, flush deal.. unless these new trans are creating contaminants in initial startup and then creating problems down the road so to speak.. so by running for 5 minutes and then flushing takes care of this issue.. the vehicle has 2K miles on it..

while I’m at the dealership there’s another XT4 there that has been brought in on a flatbed after the transmission puked out all the fluid.. turns out a gasket was left out at assembly.. natural gas in spanish I haven’t had a chance to look into who builds this 9 speed for GM and whether it’s used on other vehicles yet, but I’m certainly going to look into that..