I have an 07 yukon that I’ve had nothing but trouble with since I’ve bought it seems like. We used it to go trick or treating and piled all the kids in the back and drove with the hatch open so they could hop in and out as needed, got a service suspension light. A few days later got service stabile track light, service traction control and the park assist was turning off and on while driving as well as a flashing abs light. Twice while driving the speedo has quit working and when that happens it shifts REALLY hard into 2nd and pretty hard into 3rd. It’s completely random and sometimes you can hop in it and make your destination with no lights or problems, other times not so much. Replaced negative battery cable and have cleaned all chassis grounds with no success. Anyone else have this issue?
The service suspension message probably stems from leaking air shocks on the rear or possibly the compressor or both. You had the hatch open with people sitting all the way at the rear. The auto leveling sensors detected the added weight and probably commanded the compressor to turn on and inflate the rear shocks to compensate for the added weight. Something (shocks or compressor or both) didn't function as intended, so it set the message on your dash to let you know it wasn't working properly.
The Stabilitrac, Traction control, and ABS are all tied in together... it could be something as simple as a wheel speed sensor.
The speedo working intermittently is most likely caused by low voltage. These trucks have ECM, TCM, BCM, etc and they can be finicky and act up when the voltage gets low.
Changing the ground cable on the battery is a good start but only part of the equation.
I would start by having the battery load tested to be sure it isn't on it's way out and then replace the positive battery cable as well as make sure all of the cable connections are clean and tight. Also the under hood fuse box on the drivers side wheel well is a known spot for possible corrosion where the fuse box seats down onto the connections underneath. Grab the gray handles on either side of it and lift up and pull up on the fuse panel to disengage it from the connectors and take a look at them for corrosion. Clean them with electrical contact cleaner and then spray them down with some dielectric grease or something similar and reseat the fuse box down on them and lock the handles back down.
A good scan tool, like the Tech2, can give you a better idea of what is causing the ABS, etc. lights instead of just guessing at it.
Hope this gives you a starting point and fixes your issues.
