crank position sensor question

[808kj]

I just got a 2002 liberty, 2.4L, 5 speed, cranks but wont start (no spark) While trying to start it with my scanner in live data the engine rpm shows 0. It has a code P0320. The crank sensor is getting 5v to the power wire, The sensor output wire also has a steady 5v while cranking. So before i get a new sensor I figure id ask some opinions, do you think it is a wiring problem or the sensor itself?

 

[tjkj2002]

You need a scope to properly test a crank sensor as it gives off a square wave pattern not picked up by a DVM.


Just make sure to get a OEM crank sensor.

 

[808kj]

Ok, Do you know if there should be continuity between the signal wire and the power wire with the sensor unplugged? There is which is why i was suspecting the wiring.

 

[808kj]

I just reread your post, I used both a analog and digital multimeter while testing the signal wire, With the Analog one the needle didnt even move at all. I know this wouldnt be as accurate as a scope but I figured I would atleast see the needle bounce around a little bit.

 

[tjkj2002]

The crank sensor should be a 3 wire sensor,1 wire is the 5 volt referance signal,1 signal wire,and the last 1 is ground.

When cranking that signal wire should switch from 5v to 0v then back again,this happens very fast and much to fast for any multimeter to show.At normal cranking speed of say 250rpm's that sensor can switch from 5v-0v about 7000 times.


The proper way to test the crank and cam sensor is check for 5v referance,good ground,and then scope the signal wire while cranking or with the engine running.

 

[808kj]

Just an update, got the new crank sensor in the liberty is now running

 

[06Renegade]

This sounds similar to the problem that my 06 Renegade is having. The problem is, I replaced the crank sensor and still have no spark. Any other suggestions?