Starting to have a serious but unusual problem with the shift indicator on the dash while on a long trip West!! Sometimes it fails to show exactly what position the shift lever is in or the entire area flashes on and off until you move the shift lever to a different position. Also had an incident where the engine would not crank and I believe it was because the lever may have not been in Park. I jumped out and raised the hood thinking my batteries had died but this was not the case because when I got back in the truck and tried it one more time it cranked perfectly. Besides, the batteries are nearly new and the cables are really clean. Is there something in the transmission or associated linkage that kills the starter solenoid if not in park??? Why would the gear indicator on the dash flash like that..........is this a warning that it is not in the correct positon?? My truck is a 2005 with the 48RE and has 115K miles.

 

Well we made it home with no further instances of a no crank problem. By researching on the Internet I think I have found the issue. A device called a "transmission range sensor" is at fault and I will replace it myself. It mounts to the outside of the transmission housing. This device sends the proper signal to the engine computer to acknowledge the correct position of the gear selector. In other words to tell it the shift lever is in park or neutral. If it hangs up or does not send the proper voltage then there is no start voltage sent to the starter solenoid. This "range sensor" goes by other names but they all do the same thing.

 

Good to know you made it home. If you wouldn't mind, please post and advise if the fix works. I'm right around 110,000 miles now, so this may be something to watch for.

 

I can duplicate the problem by very slowly moving the shift lever from D into P real real slow and easy. If I turn the key to start nothing happens. If I giggle the shift lever and try it again then it always turns over and starts. This transmission range sensor is just not making contact to show the ECM that it is in park. A slight jiggle is enough to make the connection. Something is hanging up in the sensor I'm sure. Since I'm not experiencing any further problems and know how to temporarily correct the condition if it occurs, it may be a few days before I replace it. I will certainly get back on here when I do.

 

I just ordered the part on Amazon for $53. It's a Mopar OEM and the part number is 50645489AC. Found a youtube on this problem and it stated that if you have transmission fluid around the switch or harness then the switch is leaking and this most likely causes the problem. Mine has an oily residue all around the transmission case and switch, not a lot but it's definitely coming from the switch area.

 

My range sensor was failing a few years ago so I ordered a new OEM one. I got it but made another trip before replacing it. It failed during the trip.

Rather than fooling around trying to fix it myself, I had a local independent shop make the swap. You lose a quart or so of fluid during the R&R.
Several years are now past with no further issues.

 

Just put the new range sensor in. Easy 15 minute job. Lost about a quart of fluid which was easily caught in a pan. The electrical connector was flooded with oil as was the range sensor. Cleaned the electrical plug with contact cleaner before plugging it in. Here is an excellent yourtube video on the process. This guy was spot on with his instructions and comments.
Now my gear indicator in the dash is working great, not more flashing. This was obviously my problem and it had been acting up for a while but I always thought it was me not getting the shift lever into Park properly. Time and time again I would get the beeping horn when quickly exiting the truck even though it showed I was in Park. Part cost $53 online. Easy fix!!

 

Thanks for the update. Glad you got it fixed.