Pretty common mistake around these parts calling the ESS (engine speed sensor) the crank sensor (CPS, crank position sensor).
The CPS is only used on the early 24 valves to regulate it's electronically variable timing and is located by the starter.
I've been told that some dealer parts depts computers call the ESS a CPS, find it hard to believe as none of the dealers I've dealt with do.

When the ESS appears to be the problem I check the gap, business card thickness is close enough, then check the continuity of each of the three wires between the sensor and PCM. If they check good then I replace the ESS. Hasn't failed me yet except once when the problem was the truck's owner enlarging female connectors to the point of making poor connections with voltmeter probes.
Beware of this especially at the PCM, the female connectors are cheap and flimsy, easy to enlarge or break.

 

That seems like solid advice.

Eegads, probing the PCM. That might mean I'd have to locate it. I'll do wiggle test on connection first while running. It does hum with key-on-engine-off.

Yes, Cummins calls it a speed sensor and it takes up to 2 weeks to get from Memphis who's delivery is late, NAPA has it listed as a vehicle speed sensor (Swear to god) VSS106 which does cross to the mopar part number and could be here within 3 days for more $ than the dealer, Chrysler has it listed as 4746691 and I got them to go down 10% because they didn't have it today (arriving in morning), Autozone has no listing whatsoever for it, Advance Auto has the gasoline CKP or CPS listed and pictured for this engine...

I killed about 3 dang hours this morning on this part.

Chrysler has such terrible prices usually I didn't want to go to them first. They wanted $300 for the seat cover for the bottom portion of my wifes seat recently (previous owner was fat and ripped seat).

 

It's behind the air filter box on the firewall.
Don't mess with the connector if you can help it but do look to see if anyone else has.

 

It was crank sensor.

Absolutely horrible part availability/listing in the aftermarket. Chilton really is a bad manual for this vehicle too.

I didn't think the credit card was quite .050 thick so I used feelers.

It's so nice to have AC, tach, OD and charging!

Guys, thanks so much for all your input

-ultra

 

I'm having a similar problem with my tach. Could someone please tell me where to find the sensor? I've been told it's on the bell housing? But then I've seen pictures of it on the front end of the engine. I've got a CD copy of the shop manual but as always, the problems I have with vehicles never seem to be covered in the manual.

 

Bill, follow the wires on the front of the engine down to the lower pulley and there you'll find the engine speed sensor.