Instrument clustter or ecu problem

I just spent $1500can($1000us) yesterday to have the b service and all the brake pads and rear rotors replaced. On my way home on the highway the check engine light, check oil light all came on. I also lost the tachometer. The trucks continues to drive ok. When I got home everything is fine when I stop and restarted the car. I check the dispstick and there is fresh oil. What's up? Instrument clustter or ecu problem? Ground fault problem? Moisture? I wonder if a code will be set at all. Will bring it back to the dealer ,the n th time in 3 months, sometime next week. Any suggestion to take along. Love the truck, just wish the gremlins will leave the truck alone.
"M class owner are a confused bunch"