2019 Ram 1500 Bricked/No Start Condition...Any Ideas?

[jarrettp556]

Currently stumped on why my vehicle will not start or turn to accessory or the run position when I go to push the start button.

I had the battery disconnected for a few hours checking grounds and a few other electrical issues that the truck is having. Intermitent dash lights. Checked body ground and and canbus resistence on the CAN C and CAN IHS circuits by removing connectors E and F from the BCM located on the drivers side upper kick panel. Did I brick my vehicle by doing that?

What happened: I went to reconnect the batttery back to the vehilce since i was finished for the day and the push start button wouldnt not cycle to acc or run position....yes the key fob was in the vehicle. I tried to unlock and lock the vehicle with the key fob and nothing happened. Battery is good and was replaced within the past year (12.3-12.4 VDC checked with a meter). Vehicle has power as the center lcd cluster illuminates with "Press Brake and Push Button to Start" and the radio screen illuminates as well. Almost like the RF hub is not reading the key fob signal. Also you can unlock and lock the vehicle with the controls on the drivers side door but not the key fob.

I proceed to get the RF hub out and examined it for water damage or cooked electronics since I had both the third brake light leak and the rear window fram leak. Looked fine, nothing obvious, gave a quick clean with IPA and reinstalled and reconnected. Still nothing with the fobs and still able to unlock with driver door controls. What changed?

• Now when I lock all doors and walk away the vehicle horns 3 times as if im leaving the fob in the vehicle when in reality i am not.
• Also center screen displays "No Key Fab Detected" when I press the P/S button with the fob not in the vehicle.
• Additionaly it will sometimes display "Press Start button with Keyfob" acting like the fob is dead.
• When the fob is in the vehicle and the P/S button is pressed nothing happens and the "Press Brake and Push Start Button to Start" message appears and the ignition doesnt cycle.

I then check fuses under the dash and all are in good working order, disconnect the battery and reconnected it. Now what happens?

• Key fob is still unresponsive by the vehicle and unlocking and locking is only done by drivers door controls.
• Screen still displays the same messages with and without the keyfob present in the vehicle.
• Locks doors with drivers side door controls and walks away....no three beeps of the horn.
  • Proceeds to unlock drivers door with physical key and alarm goes off...thats normal and happens sometimes.

At this point im so confused. Did the RF hub loose the programming to the keyfobs while the battery was disconnected? Feels like the keyfob not being able to do any commands to the vehicle is a big clue. Also why doesnt the vehicle cycle through acc and the run when pressed with the fob in the vehicle? Any ideas would be great.

 

[Merlin]

I don't know if this will work, but place the key fob on the start button and push it in to try starting it when you press the brake. It may need to read the RFID chip in the remote. Just a thought.

 

[2021EcoDiesel]

Perhaps the RF hub under the backseat? I don’t know much about it but I believe that receives the signal from the key fob and could brick the truck.

 

[jarrettp556]

Perhaps the RF hub under the backseat? I don’t know much about it but I believe that receives the signal from the key fob and could brick the truck.

Yea I would think if it can't receive signals from the keyfov it could brick the truck. I opened it up and didn't see anything damaged, corroded, or burnt. I wouldn't think disconnecting the battery and checking grounds and or connections while the battery is disconnected would brick the RF hub.

 

[2021EcoDiesel]

Yea I would think if it can't receive signals from the keyfov it could brick the truck. I opened it up and didn't see anything damaged, corroded, or burnt. I wouldn't think disconnecting the battery and checking grounds and or connections while the battery is disconnected would brick the RF hub.

Ooo my apologies. I must’ve missed the part where you mentioned the RF hub in the original post.

 

[kapinallinen2]

Should not brick it.

 

[jarrettp556]

Ooo my apologies. I must’ve missed the part where you mentioned the RF hub in the original post.

It's all good. Also the hazards do not work when the button is pressed on the dash. I don't think the brake lights come on either when the brake pedal is pressed. Is there a short to ground somewhere?

 

[jarrettp556]

Should not brick it.

You would think it wouldn't. I've had the battery disconnected overnight before and have reconnected it the following morning and no issues. Weird and very head scratching.

 

[Kyle_24]

You would think it wouldn't. I've had the battery disconnected overnight before and have reconnected it the following morning and no issues. Weird and very head scratching.

Currently stumped on why my vehicle will not start or turn to accessory or the run position when I go to push the start button.

I had the battery disconnected for a few hours checking grounds and a few other electrical issues that the truck is having. Intermitent dash lights. Checked body ground and and canbus resistence on the CAN C and CAN IHS circuits by removing connectors E and F from the BCM located on the drivers side upper kick panel. Did I brick my vehicle by doing that?

What happened: I went to reconnect the batttery back to the vehilce since i was finished for the day and the push start button wouldnt not cycle to acc or run position....yes the key fob was in the vehicle. I tried to unlock and lock the vehicle with the key fob and nothing happened. Battery is good and was replaced within the past year (12.3-12.4 VDC checked with a meter). Vehicle has power as the center lcd cluster illuminates with "Press Brake and Push Button to Start" and the radio screen illuminates as well. Almost like the RF hub is not reading the key fob signal. Also you can unlock and lock the vehicle with the controls on the drivers side door but not the key fob.

I proceed to get the RF hub out and examined it for water damage or cooked electronics since I had both the third brake light leak and the rear window fram leak. Looked fine, nothing obvious, gave a quick clean with IPA and reinstalled and reconnected. Still nothing with the fobs and still able to unlock with driver door controls. What changed?

• Now when I lock all doors and walk away the vehicle horns 3 times as if im leaving the fob in the vehicle when in reality i am not.
• Also center screen displays "No Key Fab Detected" when I press the P/S button with the fob not in the vehicle.
• Additionaly it will sometimes display "Press Start button with Keyfob" acting like the fob is dead.
• When the fob is in the vehicle and the P/S button is pressed nothing happens and the "Press Brake and Push Start Button to Start" message appears and the ignition doesnt cycle.

I then check fuses under the dash and all are in good working order, disconnect the battery and reconnected it. Now what happens?

• Key fob is still unresponsive by the vehicle and unlocking and locking is only done by drivers door controls.
• Screen still displays the same messages with and without the keyfob present in the vehicle.
• Locks doors with drivers side door controls and walks away....no three beeps of the horn.
  • Proceeds to unlock drivers door with physical key and alarm goes off...thats normal and happens sometimes.

At this point im so confused. Did the RF hub loose the programming to the keyfobs while the battery was disconnected? Feels like the keyfob not being able to do any commands to the vehicle is a big clue. Also why doesnt the vehicle cycle through acc and the run when pressed with the fob in the vehicle? Any ideas would be great.

It really sounds like your RF Hub lost its program with the key or bad RFH.

Does your ignition button light up?
If it does not and your key fob wont lock or unlock your truck, I am leaning towards your RF Hub. A quick check you can do on your RFH is pull the board and on the back, you will see a big MLCC capacitor. Take a quick resistance reading and see if it is OPEN or CLOSED. If it is CLOSED, you have a bad board/capacitor to send the board power.

Hope this helps if you have not figured the issue out yet!

 

[MannyN]

First of, you cannot check a component individually in a complete circuit. A capacitor cannot be checked with a multimeter in resistance mode. Without knowing the diagram of the circuit, you don't know if there is a coil across the capacitor or a small resistor or a diode. If you want to check a component, you have to at least isolate one leg of said component. And no, you cannot replace the RF Hub on your own, it has to be programed by the dealer to your specific VIN. You can use JScan to program your key fobs but not AlfaOBD.

 

[Ripper]

I'm going to point out the obvious so don't flame me. Have you tried putting a new battery in the FOB? I was having problems with my Wrangler recognizing the FOB and I replaced the battery in the FOB, even though it was maybe a year old, and my problems went away.

 

[MannyN]

I'm going to point out the obvious so don't flame me. Have you tried putting a new battery in the FOB? I was having problems with my Wrangler recognizing the FOB and I replaced the battery in the FOB, even though it was maybe a year old, and my problems went away.

Even a FOB can start your truck without a battery in it. If the FR Hub is working, just push the start button with your dead FOB and it will start.

 

[Ripper]

Even a FOB can start your truck without a battery in it. If the FR Hub is working, just push the start button with your dead FOB and it will start.

I didn't know that. Makes sense now that I think about it for a few minutes.

 

[Kyle_24]

First of, you cannot check a component individually in a complete circuit. A capacitor cannot be checked with a multimeter in resistance mode. Without knowing the diagram of the circuit, you don't know if there is a coil across the capacitor or a small resistor or a diode. If you want to check a component, you have to at least isolate one leg of said component. And no, you cannot replace the RF Hub on your own, it has to be programed by the dealer to your specific VIN. You can use JScan to program your key fobs but not AlfaOBD.

Just a heads up I got my new RFH in today and took a resistance reading on the new MLCC Capacitor and it read 400ohms and rising compared to the old one that read 0.1 which indicates a short. I understand that checking a capacitor the best way is using pF and getting that reading and also isolating it but in a pinch you can get pretty close with a resistance reading.