CPS Test Question

2000XJ, no start, no spark, strong cranking condition. 4L

When using the autorange on my fluke 88v, I get 450kilo ohms.

I've heard you want it set to 1-10kOhm and look for 0L scale but my meter does 600.0 Ω, 6.000 kΩ,60.00 kΩ, 600.0 kΩ, 6.000 MΩ, and 50.00 MΩ. and it reads OL for 6kOhm and 60kOhm, but if I goto 600kOhm or mega ohms I see a resistance value of 450 or .45mOhm. Is the resistance supposed to actually be infinite or just REALLY high?

Ohm meters are seldom exact. I usually go to a higher ohm scale, wipe off my test leads with solvent (to remove body oil) touch to the two leads together, without touching the leads with my fingers and see if I get zero. Anything other than zero is error and you can factor that into your test.

The last time I tested my 96 it tested infinite ohms between the B and C at my connector ( I cleaned my connector with solvent). I started out with the (on my meter) 200 ohm scale, then switched to the kilo ohm scale etc. Trying to see if I had any leak whatsoever. The test (criteria) said infinite ohms, I took them at their word.

The fly in the ointment was mine tested OK, infinite ohms, but actually had a short between the A and B pins. The 5 volt power supply and the sensor ground. I think I remember my resistance as being .2 ohms or just about a dead short.

Different sensor power supply voltage in different years, some have 5 volts, some of the earlier models have 7 volts, some of the later modes 8 volts or even higher. The one constant is, the sensor supply voltage reads low if the CPS (or the syn sensor) is shorted.

You can read ohms through your finger tips, oil will affect the ohm readings, as will any moisture. I get any suspect reading I most always clean up the test point and my test leads and repeat the test, using different ohm scales.

From the factory a cps usually seems to test between 15 and 20k depending on your meter...thus if you set it at 10k and get an infinite reading, you're good. 450K sounds absurdly high

Set the meter to 10 or 20K. A good CPS will read low ohms, like a few hundred, or Infinite depending on your meter or meter settings. Over 1,500-2,000 ohms is failed.

My brand new spare genuine Jeep CPS reads about 250 ohms.

Re: Re: CPS Test Question

Tim_MN said:

Set the meter to 10 or 20K. A good CPS will read low ohms, like a few hundred, or Infinite depending on your meter or meter settings. Over 1,500-2,000 ohms is failed.

My brand new spare genuine Jeep CPS reads about 250 ohms.

Click to expand...

Well then I think it's time for me to get a new multimeter...that or I'm thinking about something else...which is always a possibility. I would trust Tim on this one

I noticed I was probing the wrong pins, the diagram in the FSM actually shows the harness side connector and not the connector from the CPS, so I was checking 1 and 2 not 2 and 3.

When probing the ground and signal terminals I observed .3 Ohms.

Safe to say the signal was shorted to ground. 10 minutes, new CPS installed fired right up.

I was starting to get worried that it might be PCM because there was no intermittent failure and I was getting good resistance values. The good CPS actually had like 250kiloOhms between pins 2 and 3 so its safe to say its not infinite just REALLY high resistance.

The FSM actually doesn't have a resistance value for the CPS in it that I could find, at least not the 2000 version.