Where is the RPM sending unit located on a 94 Cummins B-Series. My RPM gauge does not work and I need to find the sending unit, to replace it.

Thank you

 

Front of the engine block just above the crank it is called an "ESS"
Engine speed sensor when it quits you lose the tach and the charging system since the computer does not know the engine is running.

 

my 94 is mechanical and runs fine. It has no computer.

 

Your 94 has a PCM which controls the charging system that is where the voltage regulator is located.

PCM = performance control module = COMPUTER !

I did not say it would not run fine just that your battery would not charge.

I see you sig says rv which may be set up different to charge battery than a normal dodge pu set up for which i have told you exactly how it works.

 

Also when you say your engine is a mechanical setup that would only apply to the type of fuel injection system which would be a second gen 94-98 12 valve. After that they were a 98 1/2 -2002 24 valve electronic injection hybrid meaning electronic injection pump with mechanical injectors.

Does that make the picture more clear for you ?

 

The tach signal comes from the alternator on a RV.
There are 3 terminals on the back center of the alternator(usually a Leece Neville)(if the alternator was replaced by a Delco- no tach output on those but a modification can be done) and the center one is where the tach signal comes from.
No alternator charging- no signal.
HTH

 

He was told all of this info about the RV setup's last year 12/2009 so i don't know that he actually knows what he is up to.

 

PCM = Powertrain Control Module






That is all.

 

Same difference and concept still a control module (computer/micro processor) that manages the performance of the engine/drive train.

In the good old days (of early computer control) before your time when you were 10 years old the mopar performance catalog 1995 actually calls them a "high PERFORMANCE engine controller" and in the mid 80's all they did control was engine performance or management.

Not trying to flame that is just the way it has evolved.

 

Actually, you read, typed, and quoted it, but missed it Rattler. Mopar Performance catalogs are performance hop up parts- anything in there is an upgrade and when they refer in there to a "high PERFORMANCE" anything, it is just that and has nothing to do with that part's function by nature.
I had typed out a paragraph reply to this yesterday stating that and more and decided not to bother...The first PCM's (called engine controllers - or EEC) only monitored a few sensors and lit up the "idiot light" (check engine) when something was out of the expected values- fuel injection control and smog pump monitoring really. PCM really didn't take hold until they were controlling the transmission as well as the engine in one computer unit. That's how they evolved.

PCM has always stood for Powertrain control in every factory publication I have ever seen- and being that I work for a specialty dealer of automobile factory publications, I have seen more than my share. (I literally have a library of service manuals at my fingertips) Now if they could come up with a better name and abbreviation for the "MIL" light...or change the little icon to something other than "check engine" people would start understanding they are the same thing.
Anyway- none of this has anything to do with the OP's question- who I speculate found a problem in their vehicle when they first posted and never got around to working on it so reposted here... now how long before they return to view the answers here is the question.

 

I typed and quoted it from memory not bad i guess for a guy with some grey hair and a lot of cars + trucks over the years and still currently.
Yes i know full well what the catalog is for as well as it's predecessor the direct connection catalog.

The first ones (electronics) were before actual mopar fuel injection and were analog based systems.

Actually the very first one was called the ECU

(Electronic control unit) other wise known as the electronic ignition system control box which first came into production on the 1972 model year. The first performance version was the P4121505 (orange performance box)

Check your library the first digital based control units were on the 84 2.2 turbo cars with the 2 piece computer system you had the spark and charging control computer on the D.S inner fender, the hall effect distributor and the logic (performance control module) behind the kick panel. Yes there was another computer system that started in 81 on the carburetor fueled engines but again that was an analog based system on the fender. Don't forget the 318 lean burn systems,the ECM, TBI, EFI, ect, as well if you really want to dig it all up.

So back to the OP issues put what ever alphabet designation on it you would like, my post #2 is still the correct answer.

Feel free to pick on my calling a 24 valve system a hybrid computer/mechanical if you would like to as well since your library won't state it exactly like that either.

As i had very clearly stated i was not trying to flame him on it !

By the way you did not spell out your EEC designation correctly EEC = Electronic Engine Control .

 

True- I didn't spell out the EEC, and UI forgot the ECU... the way you typed it was as if you had it in front of you. and misinterpreted what it meant. No disrespect intended. you are quite correct, never seen anything associated with the VE system as hybrid mechanical/electronic. Not sure I agree with that classification, but that's another thread.

Your post #2 is correct in Dodge truck applications of the 12V for certain, and is correct for many other applications of the 12V as the ESS is a Cummins part, not a Chrysler part, but I can't say for certain that his particular motorhome uses that same ESS system since Cummins will supply engines as the customer/OEM wants them, and the chassis supplier or OEM (could be 2 different companies for that matter) who spec'd them may have chosen a different method. Only the OP looking at the engine will expediently tell.