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Unread 09-16-2008, 09:48 PM   #1
ExxxJay
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1997 XJ Cherokee 
 
Join Date: Apr 2008
Location: Forest Grove
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4.0 cranks, no start.

Hey all,

Went to start the Jeep this morning after parking it in the driveway and all it did was crank over, no start.

Dammit.

I got home and researched the threads and tested the Crank Positioning Sensor (CPS) on OHM resistance, I am not sure what B and C are, i think that I got it right and there is no resistance on the ones that I think are B and C.

The check engine light is not on with the key in the on position, but would it be for a CPS issue? Would this show up on a scan, or if there is another sensor out would it show?

I did spray carb cleaner into the intake and no start either, not so much as a stumble.

Advice?

Thanks all, it was running fine when I shut it off. I was leaning towards fuel pump but now am not sure, it is acting like spark.

Thanks, I appreciate any direction....


~Brian

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Unread 09-16-2008, 09:57 PM   #2
XJohnnyC
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Check for spark.

My buddy's Jeep was acting the same as yours. We were absolutely sure that it had to be the CPS, even though he had changed it last year.

For the heck of it, we pulled the ignition coil from his other Jeep...and it started right up.
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Unread 09-16-2008, 10:02 PM   #3
ExxxJay
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By the way...

Pulled a wire, placed a random spark plug in there and grounded it out against the ac pump, had my son turn it over and no spark....
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Unread 09-16-2008, 11:12 PM   #4
BrunoS
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dead CKP pickup on the trans bellhousing.

try unplugging and replug in the connector going to it near #6 injector and try restarting. works 30% of time to get started.

hook up ohmmeter to connector while disconnected and watch while cranking.

should pulse. this is the pickup dectector on the bellhousing picking up crankshaft rotation. this pickup synchronizes spark for the computer.

common failure, a little tough to get to but extensions and go from underneath, driver's side.

note:

the other "hall effect" pickup is under the distributor rotor, and synchronizes fuel injection timing. on the 4.0's, the distributor does NOT control spark timing, just injector timing.

quick check:

disconnect battery. reconnect after 10 seconds.

crank motor (not start)

pull trouble codes.

if it shows code 11 ....then you have a bad CKP sensor. (in the case of no spark)

in the case of no fuel...and code 11....then bad CPS sensor in the distributor.

also check ASD relay next to A/C relay under the hood, swap, and try to crank. in rare case, this 30 amp relay goes bad. it is identical to the a/c relay.
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Unread 09-17-2008, 11:33 AM   #5
ExxxJay
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Thanks BrunoS!!

I appreciate the help...

I did the OHM's resistance test on the B and C terminals, but was unaware that needed to be cranked. Is this done with the B and C terminals? and by B and C it is the 2 right-most tabs with the Tab up for the connector?

And these Relays are on the passenger side under the hood towards the front, right?

ASD, This is more than likely gonna be obvious, but what is that standing for again?

If I get a scanner from a friend, this will detect the issue?

Thanks again for the input, need to get this thing back on the road by the weekend for a run!

Have a great day....
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Unread 09-17-2008, 12:14 PM   #6
CJ7-Tim
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Quote:
Originally Posted by ExxxJay View Post
all it did was crank over, no start.

The most likely cause of it cranks and cranks but won't start up is the Crank Position Sensor (CPS). CPS failure is very common. The CPS can stop working with no warning or symptoms and the motor will not run.

Symptoms -

Fuel gauge and voltage gauges may not work or display properly.

You sometime will have No Bus on the odometer after 30-60 seconds.

NO spark.

Fuel pressure is OK

If the CPS is failed sometimes the OBDII code reader cannot make a connection to the computer or cannot read Check Engine Light/MIL codes because the CPS has failed.

Diagnostic steps to confirm the CPS is the cause of your no-start

You might be able to verify a bad cps, by unplugging it, and turning the ignition key to on. If the voltage gauge and/or the fuel gauge now displays correctly, replace the CPS.

Exchange the fuel pump relay and the ASD relay with one of the other similar ones in the PDC to eliminate the relays as the cause of the no-start.

Eliminate the NSS as a cause of no start. Wiggle the shift lever at the same time you try to start. Put the transmission in Neutral and do the same. Do the reverse lights come on when the shifter is in Reverse?

Begin with basic trouble shooting of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables and replace as needed. Do the same for the grounding wires from the battery and engine to the Cherokee's frame/body.

CPS Testing


Crankshaft Position Sensor Connector





TESTING PROCEDURE 1991 – 2001 4.0L H.O. engines

1. Near the rear of intake manifold, disconnect sensor pigtail harness connector from main wiring harness.
2. Place an ohmmeter across terminals B and C (SEE Image). Ohmmeter should be set to 1K-to-1OK scale for this test.
3. The meter reading should be open (infinite resistance). Replace sensor if a low resistance is indicated.

TESTING PROCECURE for 1987 – 1990 4.0 L engines

Test # 1

Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the CPS and measure across the CPS connector's A & B leads. Your meter should show a CPS resistance of between 125 - 275 ohms. If the CPS is out of that range by much, replace it.


Test # 2

You'll need a helper for this one. Set the volt/ohm meter to read 0 - 5 AC volts or the closest AC Volts scale your meter has to this range. Measure across the CPS leads for voltage generated as your helper cranks the engine. (The engine can't fire up without the CPS connected but watch for moving parts just the same!) The meter should show .5 - .8 VAC when cranking. (That's between 1/2 and 1 volt AC.) If it's below .5vac, replace it.
*
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Unread 09-17-2008, 02:22 PM   #7
ExxxJay
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Gauges work fine, fuel pressure is there, can hear fuel pump coming on at key on and start up...

If I had the leads on the right B and C terminals of the CPS, then I had zero resistance on that test pointing that the CPS is ok? Can the test for the 87-90 4.0 be utilized as well? (mine is a '97).

I will check the NSS tonight, along with the ASD relay...
What the heck does ASD stand for?

It is acting like and the history of the CPS sure points to that as the issue, but with no resistance on the one test (if I did the damn thing right.) I am leaning towards something else...

Thanks again for the help, sorry if I am not getting this....
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Unread 09-17-2008, 07:21 PM   #8
CJ7-Tim
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Zero resistance makes me believe that the CPS is Good.

NSS problems will give you no cranky unless you jiggle the shifter.

Bad CPS gives you lots of cranky and no starty.

ASD is the Automatic Shut Down relay.
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Unread 09-17-2008, 07:28 PM   #9
XJohnnyC
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I tell ya...go buy a new coil. If that doesn't fix it, you can always return it.
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Unread 09-19-2008, 12:10 AM   #10
ExxxJay
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Ran an OBD II Scan

Well tonight ran a scan with an actron scanner and here was the result:

P0320

Ignition / Dist Engine Speed Input Circut Malfunction.

Someone wanna translate this?

Thanks...

~Brian
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Unread 09-19-2008, 08:03 AM   #11
mhall02
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I did not get a code on mine when the CPS went (at least my little code reader didn't get anything), was getting fuel but just cranked and cranked. Like you, happened right on the driveway gettting ready to go to work, no prior symptoms. Took a chance on the CPS, since this is a common problem with the XJ, replaced and fired right up. Had about 130,000 miles and 8 years on it at the time.
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Unread 09-19-2008, 08:27 AM   #12
scupking
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Get a new CPS. I have seen so many people think its this or that and then they replace the CPS and everything is back to normal.
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Unread 09-19-2008, 06:19 PM   #13
BrunoS
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Quote:
Originally Posted by ExxxJay View Post
Well tonight ran a scan with an actron scanner and here was the result:

P0320

Ignition / Dist Engine Speed Input Circut Malfunction.

Someone wanna translate this?

Thanks...

~Brian
1) this is a generic OBD II code.

As such, when the computer can not see the crankshaft rotating...or the distributor rotating...this is your trouble code.

The IGNITION timing of the 4.0 is based on the CRANKSHAFT PICKUP (CKP) sensor on the bellhousing/trans near #6 cylinder, back of the block.

The FUEL injector timing on the 4.0 comes off the CAMSHAFT PICKUP SENSOR (CPS) located in the bottom of the distributor below the rotor and cap. this is why the manual says not to muck with the distributor since in the 4.0 it ONLY controls fuel injector firing.

The reason the 4.0 uses the flywheel for spark ignition timing is that the distributor signal used in times of old was NOT precise enough for newer smog regs so to get a more precise spark timing they went directly off the flywheel.

ANYWAYS...did you TRY any of the diagnostics steps we suggested?

Check for CODE 11 like i suggested?????

my entire bet is on a bad CKP sensor on the bellhousing.
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Unread 09-19-2008, 06:48 PM   #14
tjwalker
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Good information here...this does sound like EITHER the crankshaft position sensor or the camshaft position sensor in the distributor. My money is on the crank sensor. There are two groups of XJ owners...ones that HAVE replaced their crank sensor and the others that are GOING to replace theirs.

There is a test procedure somewhere for the cam sensor but I don't have it. Try using the SEARCH function and see if you can locate.
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