Just happened to me today on my '96 3500. I pulled out of the driveway and a mile or so later I noticed the tach had quit working and it stopped charging. All of the other gauges were still working. I turned around and at one point most of the dash lights (check engine, gen, etc) turned on for only a second, then went off again. ESS? Other ideas??? I need this thing fixed asap!!

 

check engine light? DTC's??

 

it could be your speed sensor on your dampner, just a thought. thats happened to me before

 

Yup Tach Sensor. Common. Sometimes all you have to do is clean the face off. Look and see if it has a crack in it

 

Ok, I'll check it out and try cleaning it first. The gap is .050" right?
No CEL while the truck is running. What's a DTC?

 

This happened to me. Turned out to be a loose connection on one of my neg. battery terminals.

 

DTC: Diagnostic Trouble Code. i agree with rest of the guys 90% chance its a ESS. id also check the battery connections, not a bad idea STate!

 

Battery terminals are clean, I was down that road a couple months ago. I guess I still don't know how I read codes on my truck?
Anyway, I took the ESS off the truck, cleaned and regapped it and it worked...for 21 seconds. Then the tach started jumping all over and the charging became intermittent along with the tach.
So, I guess I need an ESS. Now, where do I get one? NAPA says it's $140 and a special order. Any other ideas?

 

1994 Through 1997 Models

1

Insert the key in the ignition and turn the ignition on and off quickly in this sequence: on, off, on, off, on. Don't crank the truck. If you crank the engine by mistake, begin the sequence again as the process will be aborted.
2

Observe the "check engine" light. It will begin to make a series of flashes, indicating two-digit codes that represent the problem with your truck. The light will flash several times for the first digit, pause, then flash several more times to indicate the second digit.
3

The "check engine" light will flash Code 55 to signal the end of all codes. If your engine has stored no codes, the light will only flash Code 55.


you can get a code definition chart from a Haynes manual readily available @ny parts store or probably find a list online. i will make another post if i find them

 

When in doubt....visit Geno's garage

http://www.dodgeram.info/Engine-Gas/...fault_code.htm

 

Cummins or Genos has them for half that price http://www.genosgarage.com/prodinfo.asp?number=3924432

 

I found an ESS locally today...for $126. I NEED this truck back up and running so I drove an hour to get the thing. I installed it and no change at all. I checked the codes and I get a 12 and 42. I did disconnect the batteries recently, so that explains the 12, but 42 is for the ASD. To my knowledge there is no ASD for a Cummins truck??
What's going on here?? Like I said, I need this thing running NOW so if anyone knows what to check next let me know ASAP!!!

 

try removing the harness to the pcm. check it for corrosion and or bent pins maybe. a faulty pcm is possible but i wudnt jump to that conclusion quite yet. by disturbing the harness you cud make a better connection between the pcm and the harness if thats the problem. worth a shot and only costs you a few minits

 

Stupid question...where the heck is the pcm?

 

PCM is behind the air filter on the firewall.
There is indeed a ASD relay in the underhood fuse box.
Try swapping it with the one for the A/C