2021 Limited - Won't start, no comms, battery fine

[Nasdamus]

Hey everyone! I've got a 2021 Limited EcoDiesel that's been impeccable - until last week. I was backing into my driveway and the entire dashboard lit up like a Christmas tree. Parked, got the kids out and inside and then went back and it wouldn't start. Lights come on, running boards up and down, dash is on and ready. Push the start button and nothing. The "off" light flashes. The uconnect screen blinks. Nothing else. Car won't lock/unlock via remote (or the spare remote). I disconnect the battery and wait about 30 minutes. Get in the car, it starts right up. Red screen on uconnect about anti theft code but goes away. No other issues (and the red screen goes away after the 3-4 time of using it).

Until tonight. I've ran out twice already today, no issues. I go out, open the door, everything seems normal but no response again. Try the fobs, nothing. Battery is disconnected right now. What in the world could this be? No codes came up either. Thanks.

 

[Nasdamus]

After waiting 40 minutes last night i reconnected the battery, vehicle started right up without issue. Drove it around for a little bit, no issues or lights. Came out this morning, no response from the remotes. Doors were locked so had to use the "real" key to unlock to pop the hood. Set the alarm off at 7am. Disconnected battery (which was the only way to stop the alarm anyways). Will leave it unhooked a bit until my neighbors are up. What a nightmare this is becoming. Service is also a pain around here and no one has loaners.

 

[Ros]

This sounds almost exactly what happened to me. Wife took my truck to the pizza shop and when she parked it, all the dash lights went on like you described but it would not start. I left it there overnight and it started up fine the next morning. Took it to work the next day thinking everything was fine but the next morning, doors would not unlock with any remote and I set the alarm off three times before I gave up and had it towed to the dealer.

Issue was the RF hub. Had it replaced and so far all's well.

 

[Darksteel165]

Sounds like RF module.
Check behind/under your back seats for any sign of water.

 

[Nasdamus]

Thank you both. No water, i've been keeping an eye out on that. After i did reconnect this morning it went to hell. Started up, got non stop errors flashing on the dash. Turned it off, ran inside, came back out 5 minutes later and it was already back off. Have an appointment for tomorrow at the dealership, hopefully it'll work.

 

[Ros]

Just as an additional comment, there was no evidence of water intrusion on mine either - the RF hub just went kaput. Good luck, I hope the dealer figures it out quickly!

 

[Nasdamus]

Welll, now I don’t know. Truck wouldn’t start, decided to try and jump it for S&Gs - and it started. Tons of lights on the dash but drove fine. Watching the battery voltage it stayed around 12.9v while driving and idling. When turned off it dropped to 12.0v. Could it be a bad battery causing this? No hesitation when starting, no other issues. All lights work, running boards, headlights etc. but will not start at all (when it’s happening).

 

[kdoublep]

I bet battery if it's 12.9 while driving. These trucks are very sensitive to a weak battery.

 

[Amazing93]

My battery is 14.3-14.6, I still have the OG battery in my truck 5 years going strong.

 

[Darksteel165]

My battery is 14.3-14.6, I still have the OG battery in my truck 5 years going strong.

2019 with eTorque?

 

[GyRoCoN]

Those truck have glow plugs to preheat the combustion chamber and they draw a lot. I'm guessing if the battery Voltage is marginal the extra draw would bring it below the threshold it needs to crank over.

 

[Nasdamus]

Replaced the battery Friday morning and knock on wood, it’s just fine again. All error messages gone and has started up each time without issue.

I did take it through a car wash to test rear window and it did indeed leak at the corners. It a lot but definitely there.