Dodge Cummins Diesel Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
147 Posts
Discussion Starter #1
My check engine light is on and I did some searching on the forums and came up with the CPS. I checked the gap and it is on. I checked the power to the CPS and it is at 8v, then I checked the resistance across it and it reads an ~ of 18ohms.
Not sure what this reading means. I thing the sensor is bad but what do you all think?
Thanks in advance.
 

·
1ST GEN MODERATOR
Joined
·
16,248 Posts
I did a little playing around with a couple of CPS I have. From what I can tell the sensor is open when it sees metal. It closes when it hits the air gap in the balencer.

I know one of the sensors I have is bad. The other one is a question mark. The two I have did not transfer a full 8 volts back to the PCM. One only sent a 1 volt signal. The other was only around .05 volts. That is the known bad one. I made a jumper setup to test the one on my truck. I didn't have time to see what it is putting out.
 

·
Registered
Joined
·
147 Posts
Discussion Starter #3
Hey, thanks a lot Philip. Looking forward to hearing what a good one is supposed to read. Also, could you specify how you tested so I can make sure I am even doing it right.
thanks again
 

·
1ST GEN MODERATOR
Joined
·
16,248 Posts
Well I cheated. I have a regulated DC power supply. I just set the voltage for 8 volts and rigged the power to the correct pins. Then I just used a wrench to simulate the metal in the balencer. :D

I used the plug off the bad CPS. I took the female plug off the trash harness on my spare engine. I soldered them together and made a test jumper to use on my truck. That is after the moonsoon season goes away.
 

·
1ST GEN MODERATOR
Joined
·
16,248 Posts
Ok here is the way to test your CPS.

Black/blue tracer is the sensor ground wire. It should OHM close to zero to the battery ground.

Tan/yellow tracer is the 8 volt power feed to the sensor. The voltage regulators on the PCM's are kind of loose. This voltage can vary around some.

Gray/black tracer is the signal wire. If the sensor is on a smooth section of the balencer there should be little if any voltage showing. When the sensor is on one of the air gaps it should show around 5 volts.

If you have a 12 volt adjustable power supply. A 14 gage blue wire terminal will slide down over the male pins on the CPS. :D
 
1 - 5 of 5 Posts
Top