I have a 2000 Dakota Ext. cab, 4.7L 4WD. I replaced the crank sensor and afterward it would barely start and when it finally did, it misfires and idles all over the place, and will only run up to 2500 RPM's then it acts like it is hitting the rev limiter. I disconnected the battery and it cleared the codes but still runs terribly. It eventually set another code, P0320(?). Any thoughts or instructions on how to get the ECM to recognize and learn the new sensor?

 

Why did you replace the crank sensor?

I show P0320 listed twice in the FSM:

P0320 - no crank reference signal at PCM. No reference signal (crankshaft position sensor) detected
during engine cranking.

OR

P0320 - No RPM Signal to PCM (Crankshaft Position Sensor Signal to JTEC). A CKP signal has not been detected at the PCM.

 

Well, the Crankshaft Position Sensor was actually replaced on accident. I have had a very intermittent Crank/No Start condition for a couple of years with the P0340 and P0551 codes present. I have never been stranded as it would always eventually start. After talking to a few technicians and researching the web, I figured the Cam Sensor was the cheapest route to try (vs a PCM.) So after buying the Cam Position Sensor, I pulled the wrong one, the Crank Position Sensor, and of course the mounting tab broke, so I had to replace it. That is how I got where I am now, which is way worse than the original intermittent no start.

One tech I spoke with about it said he has seen cars with a Cam Sensor code with a bad Crank Sensor, since some of them use the Crank Sensor as a reference for the Cam Sensor.

I need to know if I can reset the PCM to read the new sensor. It only has one mounting bolt, so it can't be installed in the wrong position, correct?

 

All the crank sensors I've seen have two mounting bolts. Not that I've seen all that many...

Are you sure you plugged it in? It kinda sounds like the PCM isn't seeing a signal from it and is just running off the cam sensor or something.

 

There's one bolt on the 4.7. Make sure the connector is clean and tight.

To reset the PCM just disconnect the battery and, with it disconnected, turn the key to start. Reconnect the battery and you're done!

 

Thanks Dan. I did not try to start with the battery disconnected. I will recheck the connection and try to reset it tomorrow.

 

So I pulled the sensor back out, cleaned it, checked the connector, cleaned it with ElectroKleen, reinstalled, torqued to 21Ftlbs, turned the key to start with the battery disconnected and still have the exact same problem. It cranks and cranks, then shows the RPM's and misfires once or twice, then starts.

It seems like it's running ok with the exception of the idle bouncing around from 700-1250. When I give it gas, it starts cutting out around 2500 like it's hitting the rev limiter.

I took it for a short drive in the neighborhood and it seemed to have a significant loss of power, then I realized it was in 3rd or 4th gear and would not drop back into 1st after a complete stop or downshift into second unless I did it manually. In 1st and 2nd gear it would run ok up to around 2500, then misfire or cut out.

When I got back home I checked the codes and now it has P0320 and P0700. Do you think I could have gotten a bad sensor or is the PCM taking a crap?

 

The P0700 indicates you have a code set for the tranny. Most readers won't pull them.

You still could have a bad crank sensor but I wouldn't rule out the camshaft position sensor. They share the same power and ground wires.

Also, double check all the wiring including the connections to the PCM. Disconnect the battery and pull them off. Check for oil contamination - it happens.

 

What is the procedure for testing the crank and cam sensors?

Should the PCM have a signal (Voltage or Ohms) at the specified pin?

The Tach shows the RPMS correctly, it seems to me that the PCM is not getting the right signal for some reason.

 

Basically they are "hall effect" sensors. So yes, there should be a voltage. It should also have continuity. I don't see the specs listed in the factory service manual.