I joined your forums and read and read back in August. Learned a bit so I tackled this issue of the P0340 code. Truck starts fine when cold and if you drive to the store for instance after it heats up it won't start until the temp goes under 130. This is what I have replaced :


Cam positioning sensor
Crank positioning sensor (Mopar)
Cap and rotor
Spark Plugs
Coil
Finally today the computer
I also ran a 10 gauge wire from the negative terminal to one of the mounting screws on the computer to beef up the ground.


The new computer threw a P0320 after it died, then after trying to start code went to P0340.
I am now thinking to pull the distributor and have a look see inside and also check the shaft play and so forth.
Any other suggestions I am seriously at my wits end on this. Been a great truck for 15 years but this has just baffled me as far as repairs and diagnostic procedures. BTW the crank sensor was a mother to install.


Best,
Rebelwoc

 

Water temp sensor? Is your temp gauge working? How do you know when the temp is below 130?

How does the wiring to those sensors look, have you checked for continuity?

 

Temp gauge works perfect. I know when the temp is below 130 by the temp gauge increments on the dial. I can even tell when the thermostat opens. Haven't checked for continuity yet.

 

P0320 No Crank Ref Signal at PCM

P0340 No Cam Signal At PCM

Verify you are getting five volts TO the sensors. Check all connections, including at the PCM.

What brand sensors did you get?

 

Bought genuine Mopar crank sensor and O'reillys Cam sensor. Runs like a dream until you shut it off after it reaches operating temp. Makes no sense. I had a aftermarket crank sensor but took it back before installation after reading comments here, probably yours.

 

Something is heat-soaking, and failing...... Might try a mopar cam sensor........ no promises that it will help though.

Aren't intermittents fun?

 

Been going on for over 4 months now. at this point not much fun because I need my truck badly.

 

Check out post #4. Get a spot where you can check the voltages TO the sensors, measure them and then re-measure when it won't run.

After that, if you have voltages yo the sensors, check the output of them, same way, before and after. We need to eliminate them as a possibility.

And what about replacing your ECT too, just for grins.

 

ECT? Electronic Coolant Temperature sender?

 

Engine coolant temp. But, close enough.