HELP - Lots of power but start switch is dead (or now crazy)

[flan]

Need to individually test the batteries with a legit load tester to see how many amps they have. Volts are one thing, Amps are another. Kinda like HP vs. TQ.

 

[PRS]

Are you measuring the voltage at the battery post? Try measuring on the strap labeled St PDC in the picture. That’s the connection that goes to both the starter and the power distribution center. What you’re describing sounds like a poor voltage or ground connection. Also make sure all the fuses are fully seated.

 

[RBarrett]

I'll look at the voltage there. I assume that would show me if there was a resistance in the strap connector itself. This I can just measure as well. I fully seated the fuses back when the first no start condition showed up. I agree it seems like something is suffering from a low voltage between the key rf end of things and the low current side of the starter circuit.

 

[RamCares]

Well I violated the law of the single variable. Since I was doing so much trial and error things I put a battery charger on it last night. Then since it looks like a trip to the dealership is in the cards I pulled out my Navics module. Since this truck is still under warranty and work in the dash seems likely, it s better no questions come up over that. So this AM I got in with both keys and saw the mileage roll out in the display and the off led light on the start switch.. Pushed the start button into preheat it went and then started. It started two more times and now it is as before. I now have it in a better place and the windows closed. So much for fuse ideas. I spoke to to dealerships and yes they are backed up. Arapahoe Autonation had there shop foreman killed over the weekend and his two sons that are techs there are out indefinitely. A very unfortunate thing for sure. They said mid December maybe. I have an appointment at Larry Miller for November 4. I will call Littleton as well. Thanks for the tip. I obviously have some sort of intermittent issue going on here. I'm back on the battery charger and will try some more later. When I was in behind the 12 inch I tried to get to the connector on the start button. I couldn't really get my hand in from there. It didn't have a red wire that I could see. Looked like purple and a lighter color but not sure. Maybe I need to go in from the bottom. I have a bunch of time between now and the 4th. If I can get it started once more I can get my camper off and get it lined up for a tow truck.

Hello, We apologize for the inconvenience this has caused you. Please send us a private message once your vehicle is at the dealership, we will assist you further. Sylvia Ram Cares

 

[RBarrett]

So now my truck wants to behave nicely. After more than 20 cycles of preheat and then an engine start (with cell phone ready for a video ) it has not exhibited any problem. So I have started driving it again being very conscious of where I park in case I need a tow. I have ruled out the batteries in my own mind. With that many cycles and no run time to charge and showing over 12.5 volts it seems that can't be my problem. If there were any diagnostic codes present it seems that many restarts would likely erase them. Obviously my problem is intermittent and I question the value of a trip to the dealership now. My extended warranty requires a $100 outlay that would be better spent with a hard failure to diagnose. At least a week without the truck seems to also be the norm with dealership service. Since the Ram Cares folks were nice enough to respond to this thread I will talk to them next. They have been helpful in the past. In the meantime I'll wonder what awaits each time I go to start up my truck. No doubt it will wait until I'm way in some forest road with the camper on and no cell service to hang me up.

 

[RBarrett]

For the benefit of anybody who may have some similar issues I will expand on my trucks behavior before taking it in for service. My trucks repertoire of odd behavior expanded quickly after I started driving it again. The original start behavior is still present but now has been joined by numerous other intermittent problems. The truck will lose track of where the key fob is. Indicating it is not present in the middle of a trip or refusing to lock after getting out with the key. It will indicate that it is not in park when it is. It flashes the P and will not respond to attempts of going back to D or N or R to get it to recognize it is actually in park. The tire pressure monitoring system will randomly indicate a failure and then return later to normal operation. The remote start will work sometimes and not other times. It seems to randomly flash the the park lights and occasionally sound the horn. I have been able to drive the truck because I figured out that openning and closing a door will reset and restore normal operation in most cases but only temporarily. The only exceptions to that seem to be the park and start behavior that seem to respond to further thrashing with the doors, key fob and locks. So openning and closing my door is my new master reset for all problems while driving and most when starting or ending a trip. I made a detailed list of all these issues and how I reset them for the dealership and technician. I have an appointment with the dealship next week and will also contact the Ram cares folks since they requested I do so when taking it in. Hopefully I can get this fixed with only one trip to the dealership. At least it is no longer an obscure intermittent problem but now involves many issues that hopefully can be observed pretty reliably when the vehicle is test driven. It will be interesting to learn what they find. I'll have my fingers crossed for a straight forward fix.

 

[flan]

I can’t wait to hear what the cause of all that mess is, talk about a gremlin!

 

[CaptainMike]

Geez, what a nightmare.

 

[jsalbre]

Are you sure your truck wasn’t in a flood?

 

[Jimmy07]

For the benefit of anybody who may have some similar issues I will expand on my trucks behavior before taking it in for service. My trucks repertoire of odd behavior expanded quickly after I started driving it again. The original start behavior is still present but now has been joined by numerous other intermittent problems. The truck will lose track of where the key fob is. Indicating it is not present in the middle of a trip or refusing to lock after getting out with the key. It will indicate that it is not in park when it is. It flashes the P and will not respond to attempts of going back to D or N or R to get it to recognize it is actually in park. The tire pressure monitoring system will randomly indicate a failure and then return later to normal operation. The remote start will work sometimes and not other times. It seems to randomly flash the the park lights and occasionally sound the horn. I have been able to drive the truck because I figured out that openning and closing a door will reset and restore normal operation in most cases but only temporarily. The only exceptions to that seem to be the park and start behavior that seem to respond to further thrashing with the doors, key fob and locks. So openning and closing my door is my new master reset for all problems while driving and most when starting or ending a trip. I made a detailed list of all these issues and how I reset them for the dealership and technician. I have an appointment with the dealship next week and will also contact the Ram cares folks since they requested I do so when taking it in. Hopefully I can get this fixed with only one trip to the dealership. At least it is no longer an obscure intermittent problem but now involves many issues that hopefully can be observed pretty reliably when the vehicle is test driven. It will be interesting to learn what they find. I'll have my fingers crossed for a straight forward fix.

Sounds like the RF Hub is failing. You got a leak at the third brake light? Is the carpet under the back seat below the center of the back wall damp? The RF Hub is on that back wall.

 

[RBarrett]

No moisture that I can detect. I've had thoughts along those same lines though. If the hub is back behind the seat I'd better get all the stuff I have stashed back there out of the way before taking it in. Is rear seat removal needed to gain access to it?

 

[Jimmy07]

Is rear seat removal needed to gain access to it?

Yes.

 

[RBarrett]

Yes.

Can you give me an idea of what the RF hub actually does?

 

[Jimmy07]

Can you give me an idea of what the RF hub actually does?

It handles and verifies the commands of the fob, the push to start button, the antennas in the vehicle that senses the fob, information from the tire pressure sensors, monitors and verifies transmission gear status for starting, etc. Basically, it’s the radio frequency receiver for tpms, and the immobilizer for the ignition and fob.

 

[RBarrett]

It handles and verifies the commands of the fob, the push to start button, the antennas in the vehicle that senses the fob, information from the tire pressure sensors, monitors and verifies transmission gear status for starting, etc. Basically, it’s the radio frequency receiver for tpms, and the immobilizer for the ignition and fob.

Does it monitor door status? I'm trying to make sense of why door open and/or close seems to temporarily reset things.

 

[Jimmy07]

Does it monitor door status? I'm trying to make sense of why door open and/or close seems to temporarily reset things.

Opening and closing the door is kind of like a “canbus reset”, since it re-wakes up all the modules on the bus. Maybe the rf hub goes into some kind of “coma”, and wakes back up when you open the door.

 

[RBarrett]

Opening and closing the door is kind of like a “canbus reset”, since it re-wakes up all the modules on the bus. Maybe the rf hub goes into some kind of “coma”, and wakes back up when you open the door.
[/QUOTE]
Does the hub itself generate DTCs?

 

[Jimmy07]

Does the hub itself generate DTCs?

Yes, but not necessarily check engine lights. You need something like alfaobd that can specifically connect to the rf hub to check for faults. Scanners, such as the ones auto parts stores use to scan for faults won’t be able to do this.

 

[RBarrett]

Yes, but not necessarily check engine lights. You need something like alfaobd that can specifically connect to the rf hub to check for faults. Scanners, such as the ones auto parts stores use to scan for faults won’t be able to do this.

Yes I wouldn't expect this type of fault to set the CEL or a simple OBD scanner to be able to query the hub. I was just trying to get some insight into what diagnostic steps the dealer might take when they hook up to the truck.

 

[PRS]

With the MX+ and the included OBD Link app you can read faults from various other modules like the rf hub, if you retrieve the enhanced OEM add-ons from within the app on the settings page.