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2020 Sierra SLT 5.3L
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Discussion Starter · #1 ·
Hello to the group. I'm new here and was hoping I could get some idea as to what happened on my 20 Sierra SLT. I was on the interstate and passed going around 80 mph. Right afterwards I was back to 75 and suddenly the CE light started flashing and the dash stated flashing the message "Service Parking Brake". This went on for about 30 seconds and disappeared. I could feel some subtle jerking as I pulled off at the next. Felt like the trans (10 speed) was searching for a gear. as I began to put on the brakes there was more profound jerking lake the parking brake was pulsing.
Everything on this truck is electronic including the parking brake.

I have an OBD tester and it pulled codes P0300 (Random, multiple cylinder misfire), U0401 (Invalid Data Received From ECM/PCM "A"), U0131 (Lost Communication With Power Steering Control Module), U0102 (Lost Communication with Transfer Case Control Module) and U0140 (Lost Communication With Body Control Module).

I shut the vehicle off and checked under the hood but everything still looks pretty new under there. Checked for loose wires and didn't detect any. I went directly to the dealer and they said they would need to have their engine specialist diagnose it but couldn't get me in until 3/23. The truck ran much better on the way to the dealer and now runs like nothing ever happened. Full power and smooth. WTH!! Any ideas folks? I'm not sure anyone has experienced this exact issue but would appreciate any ideas. Thank you
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