Trying to track down the test procedures for the ess (engine speed sensor) on a 99 ram 24v.  I’m assuming it would be in hertz?  I’m trying to see if my ecm is correctly giving this reading to the pcm.  

You'll need a o-scope because the frequency varies with speed so the PCM doesn't control speed readings but the ABS computer does and sent out on the CCD bus to all modules that are listening. Like ECM, PCM, cluster, overhead trip computer, etc.

 

Module Masters in Moscow ID does rebuild the ABS computer and gives a good long term warranty.

Edited March 20, 20241 yr by Mopar1973Man

6 hours ago, Mopar1973Man said:

You'll need a o-scope because the frequency varies with speed so the PCM doesn't control speed readings but the ABS computer does and sent out on the CCD bus to all modules that are listening. Like ECM, PCM, cluster, overhead trip computer, etc.

 

Module Masters in Moscow ID does rebuild the ABS computer and gives a good long term warranty.

I see you mentioned abs computer.  So I think we’re talking about different things.  I am asking about the ESS (engine speed sensor) or what would be the crank sensor anywhere else. That also would be a varied frequency.  

Oh. Crank sensor now I'm with you. Sorry.

 

Again you need a o-scope the sensor created variable frequency as rpm rises and falls.

 

I would pull the sensor out and verify the two screws didn't fall out of the tone wheel and then the tone wheel falls off in the pan. Yes it does happen. You will most likely need to replace it being it most likely bent and crushed from the spinning crank.

 

There is a member here that had to replace the tone wheel. Oil pan comes out easy just jack the frame up allowing the front axle to hang. There will be plenty of room to pull the pan so you can fix the problem.

 

Sensor wise just need to check and see if 5V is present at the plug. But yes the ECM counts the frequency of the pulses to figure out RPM. Yeah your going need a o-scope.

1 hour ago, Mopar1973Man said:

Oh. Crank sensor now I'm with you. Sorry.

 

Again you need a o-scope the sensor created variable frequency as rpm rises and falls.

 

I would pull the sensor out and verify the two screws didn't fall out of the tone wheel and then the tone wheel falls off in the pan. Yes it does happen. You will most likely need to replace it being it most likely bent and crushed from the spinning crank.

 

There is a member here that had to replace the tone wheel. Oil pan comes out easy just jack the frame up allowing the front axle to hang. There will be plenty of room to pull the pan so you can fix the problem.

 

Sensor wise just need to check and see if 5V is present at the plug. But yes the ECM counts the frequency of the pulses to figure out RPM. Yeah your going need a o-scope.

Ok understood.  My tach is working.  So I’m pretty sure my sensor and wiring is good going into the ecm.  I haven’t been able to get any readings coming out of the ecm to the pcm on the grey/blk wire.  

All transmitted over a CCD Bus in digital signal. So you might have to send your PCM for testing. If the ECM is creating and the cluster is reading signal then the PCM has internal issues which are not capable to read tach signal off the CCD network. This is a full digital signal and very hard to decode which few have managed to do.

 

 

 

Edited March 20, 20241 yr by Mopar1973Man