Hey guys, I’m having an intermittent nagging issue with the drivetrain and I just can’t seem to get to the bottom of it. First, I have a 2007 Tahoe 5.3L with the standard 4L60E trans. Sometimes when I hop in and start it, everything is fine, but half the time the CEL comes on, DIC indicates “Service 4wd” and the transmission will be in “Limp mode.” I have visually checked the drivetrain and changed all the fluids from the front diff to the rear diff. I have taken it to a transmission shop and they just throw parts at it that’s costed me $1500 already. They changed the electronic 4wd actuator (unnecessarily), the ignition switch, and performed the TCC re flash service bulletin upon my request from past research. It was good for about 6-8 months after the service bulletin was completed but now it’s back to the same old issue. Please help! I’m tearing my hair out here. Thanks in advance!