• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

How Can I Test My CPS ?

T

TomSwift

NAXJA Forum User
Location
Florida
I just got a FSM for my 98 XJ. The reason I got it is because I am trying to fix a problem with the engine cutting out while driving, and having difficulty starting occasionally. Apparently the problem is with the crankshaft position sensor ( I had the codes pulled and it came up a P0320 ).

I Posted about this earlier and got some good help narrowing down the reason for the driving/starting trouble. Because it costs so much to replace the CPS I want to test it before I buy a new one. The problem is I don’t have a clear idea how.

The FSM doesn’t include instructions for testing the CPS and points to an additional diagnostic manual. I also got the Haynes manual just for fun and it doesn’t include this procedure either.

Does anyone have any tips on testing the CPS?
 
I know on a 91' you disconnect the sensor, connect an ohmmeter across terminals A & B...you should have a reading of 125 to 275 ohms with engine hot.
 
dizzymac said:
I know on a 91' you disconnect the sensor, connect an ohmmeter across terminals A & B...you should have a reading of 125 to 275 ohms with engine hot.
Click to expand...

The later CPS should give an "open circuit" reading from an ohmmeter and be replaced if a low resistance is found. The reading you're citing is for the Renix type. 91 was a transitional year and its CPS may differ from later ones, but all later than that are definitely this way.

The more recent factory service manuals have skimped on some information, and it appears that there's nothing at all on this in the 99 FSM, but the basic test is found in section 8-D (Ignition systems) in the 95 book.
 
Ya..I got that from Mitchells E-repair, trying to find out what shorted out the ECM in the 91' I just picked up, a dealer and a repair shop both said to check CPS.
 
is that teh only way to do it? my reads fine with resistance but i still suspect it... i read while cranking it should read .5-.8 VAC... but some seem to disagree. any thoughts?

mine reads .21 VAC
 
2 wire CPS and the resistance was like .218 ohms... thats good though casue i checked the one thats new in the box and it was the same.
 
Hey DenT, did you ever try getting the codes pulled to see if there is any code showing for a bad CPS? I was able to have mine pulled by the guys at both Discount and AutoZone for free.
 
do i even have a obdii or whatever the letters were.. connector? didnt kno there were any codes to pull... its an 89
 
Can't really pull codes from a Renix computer.

According to http://www.obdii.com/codes.html, P0320 means "Ignition/Distributor Engine Speed Input Circuit Malfunction" which I believe is the camshaft position sensor in the distributor. The crankshaft position sensor (sometimes called the CKP) is the one in the bellhousing.

Hopefully Tom has solved his problem by now, though.
 
DenT said:
how does my computer say its the cps? i tested it with a multimeter...
Click to expand...
My reply was for the person who started this thread, he has a 98.
When trouble shooting it's best to start your own thread to prevent confusion.

I should have looked the code up, I assumed it was the CPS because that what he was asking about,
 
Last edited:
lawsoncl said:
Can't really pull codes from a Renix computer.

According to http://www.obdii.com/codes.html, P0320 means "Ignition/Distributor Engine Speed Input Circuit Malfunction" which I believe is the camshaft position sensor in the distributor. The crankshaft position sensor (sometimes called the CKP) is the one in the bellhousing.

Hopefully Tom has solved his problem by now, though.
Click to expand...


According to 99 FSM, PO320 is crank position sensor.
 
lawsoncl said:
Can't really pull codes from a Renix computer.

According to http://www.obdii.com/codes.html, P0320 means "Ignition/Distributor Engine Speed Input Circuit Malfunction" which I believe is the camshaft position sensor in the distributor. The crankshaft position sensor (sometimes called the CKP) is the one in the bellhousing.

Hopefully Tom has solved his problem by now, though.
Click to expand...

Sorry I left this thread hanging. After trying to use the new fancy multimeter I got at Discount with mixed results, I finally gave in and just put in a new one which fixed the problem. There are two things that I learned from this process that may be helpful for some people..

1. With an 18" extension and a U-joint it is possible to do it from underneath the truck on a 98.

2. If you live in Florida ditch the major autoparts chains. I got a new csp from Central Auto Parts for about 40 bucks cheaper than both Discount and AutoZone were trying to charge.

Best of luck.
 
good to kno... actually did a lil experiment on this rainy day and hair drier'd the coil and got the sucker to fire up... fun fun thats the first thing to get replaced. Thanks for all the help fellas
 
You must log in or register to reply here.

Similar threads

Anak
How to Slot the CPS
Replies
2
Views
104
Rob Mayercik
R
Xtreme XJ
Crank, no start even with new CPS...
Replies
13
Views
2K
Xtreme XJ
Xtreme XJ
M
Installing heated factory seat
Replies
3
Views
839
mortenhj
M
B
Reasons for white exhaust smoke besides head gasket?
Replies
1
Views
825
RCP Phx
R
R
Splined output shaft ax-15??
Replies
0
Views
23
rockosocko
R
Back
Top