This is like Ahab searching for Moby Dick.

Good info though, somewhat, that all those part numbers are the same thing, just newer versions of the part. Kinda sucks though that there was no verification as to what the revisions were to the sensor, I'd be interested to hear what they were...

Good to know that the $85 one you found is most recent revision of it.

-J

 

I called L&J Diesel in Jacksonville, FL about this. They are a big Cummins and Bosch dealer. The guy I spoke with there gave me some interesting info, but I'm not sure about it's accuracy.
He said that there has been a "field fix" noted in the part information, which was made due to some trucks experiencing surging. He said it has to do with the alternator.

According to him, some trucks have a Delco 24SI alternator. With this alternator, the truck needs to use a particular sensor or there can be surging problems. Trucks with another type alternator can use either sensor. Hmmm....

I'd like to compile a list of truck year, factory alternator model, and Bosch part # (on original RPS) to see who has what, and possibly determine if this is causing/contributing to the surging some trucks have.

 

That is interesting... ANY truck? Or modded ones in particular? So [assuming the information received is accurate] if the old part was superceded by the new one, would a truck in need of an RPS have to first see what alternator they had, and go from there? Furthermore, if their alternator put them in the realm of needing the "old" RPS, would they be SOL if only the new one was in production?

I think I worded that right...........

-J

 

Some clarification, or more info:

We need a Cummins guy to look up some TSBs. Andre at L&J Diesel in Jax said that there are two TSBs associated with Cummins part #3949988. TSB 070045 Oct 02, 2009; TSB 100704 Jun 25, 2008.
I have not read them yet, but one says if you have the Delco alternator you need to use the 3949988 sensor because using the newer one (3974092) will cause a surge under certain conditions. The other TSB is about the alternator, and says something about an updated alternator to cure a surge.
I would like to read the actual TSBs. I am not sure if this is the surge at idle/low rpm and occasional no-start, or if this is the surge with cruise control.
Any Cummins guys that can get the TSBs?

 

For now, I would say that if your truck doesn't have a problem, then your RPS goes bad, make sure you replace it with the same Bosch# that is on your sensor.

 

PDP RPS Cummins 3974092/ Bosch 0 281002 863

 

Do you know a way to test a RPS with a voltmeter to determine if it is bad. Or Ohm it out or something.

I will get you the part numbers off of it tomorrow

 

Well, somewhat disappointing news: I have both TSBs and they refer to electrical interference between the newer sensor (3974092) and the Delco 24 volt alternator. These TSBs are targeted at the mid range engines (that use 24 v systems) and describe an incompatibility between the new sensor and alternator. One TSB recommends replacing the new RPS with the old RPS. The other TSB has a replacement alternator.
Unfortunately, there is no mention of 12 volt systems being affected.
This leads me to wonder if the surge in our trucks is similar, or something completely different. Sorry, no major break through yet. Keep working at it!

 

Hey guys. I found myself in need of a rail pressure sensor after getting mine wet when giving my engine bay a thorough detailing. After a few calls and help from this post, I was able to get one ordered. I had my local cummins dealer run my serial number to make sure the correct sensor was getting ordered. I found some interesting info. Cummins part number 3974092 is correct but has already been superseded by part number 5260246. So, if any of you still need this pesky guy, it's now under that part number. Hopefully I'll get my new sensor by Wednesday so I can get my truck back on the road...had to ship from Atlanta. ~$140 screw up...not happy! I'd like to blame the quadzilla RP gauge harness for not sealing the sensor as well as the stock connector would have but who knows if that's even a legit excuse