Napa calls the engine speed sensor the "crankshaft sensor" part number: ECH CSS635 . Like I said, facing the engine from the front of the truck the sensor sits at 10 o'clock then the harness weaves its way towards the drivers side of the engine.

When my truck did the same thing as yours the ESS was out and there was also a high amp fuse in the under hood fuse block that was blown. Dodge was the only place I could find a replacement fuse. I would check to see if that fuse is blown. If it is replace it then try disconnecting the ESS again.

Fixing both of those solved my problems so if that doesnt fix it for you I'm out of ideas.

 

Yeah, so I did unplug the sensor itself, same results...gauges did not return. Exactly which fuse was blown do you remember. The reason I asked is that I have checked all fuses in both the inside block, and the block mounted on the driver side wheel well.

 

Id take a picture of my under hood fuse block (power distribution center aka PDC) and highlight the fuse for you except my truck is currently 6 hours away from me. If I remember correctly it is a square 200 amp fuse. If you follow the power leads into the pdc it should sit very close to where the leads enter. You should be able to see if the fuse is blown without removing it .. ie it should have a clear top.

 

Ok...yeah, mine is 140 amp fuse and I have tested that one, it has continuity, so I assume that it is good. I pulled my CPS (ESS) and tested for the 5V.....I'm only getting 1.15V to the plug for the sensor...any ideas on that?

 

Not sure about the voltage levels. Let me back up for a minute. Does your engine run with the current problems? Will it crank over? When I unplugged the ess and turned the key the wait to start light returned and the fuel shutoff solenoid snapped up. When you unplugged your ess and turned the key what happened? Also, this will sound dumb but are the batteries fully charged? When mine quit the alternator wasnt charging and both batteries went dead.

 

Yeah engine will run and truck will engage and drive. Brand new batteries, have bench tested alternator...been following the forums here and doing what others have done. Just got off the phone with a Dodge tech here locally. He said that with that low of voltage to the circuit that it sounds like a ground issue within the PCM itself... the tech asked the battery ? too....good place to start.
I did remove the ESS and turned the key, I received the exact same results No WTS light. These are the lights that come on when key is turned: WATER IN FUEL, TRANS TEMP, AIR BAG, CHECK ENGINE, BRAKE, CHECK GAUGES. They come and then go off as they normally would. The needle gauges just move the slightest bit then no reponse from them. Have double checked all relevant fuses, power supplies on the PDC, ensured 12v into PCM, and continuity to ground on all appropiate PIN connector. Verified continuity from CPS plug signal wire to pin terminal -good. Power lead continuity to plug and ground continuity to plug....all good. Tech said that you can't read the resistance on the sensor itself, although I have read in posts that it should be between 500 and 900 ohms. Yet, following what you said about the sensor. It seems that removal of the short circuited sensor allowed the PCM to power back up and supply power to the gauges, which is not happening in my case.

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I think the reason the truck will drive is that it is in "Limp Home Mode", I have read that a failure will default the truck to this and it will hold and apply the last calculated values....but not solid that is happening due to no PCM.

 

Isnt electrical work fun! So its sounding like the ess isnt your problem .. but something is still causing the pcm to see a voltage it doesnt like. When my ess went bad it caused a short and shut everything down. When I turned the key on all of the lights you mentioned would come on and go off as normal but the engine wouldnt start. By unplugging the sensor I was able to start the engine but since the pcm wasnt getting a signal from the ess it wasnt allowing the alternator to charge and the tach didnt work. When I put the new ess in the alternator started charging and the tach worked again.

I suppose you could try replacing the ess with the junk yard piece but like I said it is sounding less and less likely that your ess is the culprit. Beyond that I guess you will need to look for loose pins in all of the pcm connections .. that and start cleaning grounds.

 

That's what I am starting to think as well....because I used the junkyard piece and nothing different occurred. Did any of your other gauges work with the bad ESS, I noticed you said the tach and alt, but did oil pressure, voltage and temp gauges come up?

 

I couldnt start my engine with the bad ess so none of the gauges worked until I unplugged it. After that when the engine started I had everything except for the tach .. the voltage gauge did work but it was reading between 8 and 12v ie the alternator wasnt charging and the voltage been read was from the batteries.

 

My money is on a bad PCM... same thing happened to me less than a year ago and that's what it was.