Went to start the Jeep this morning after parking it in the driveway and all it did was crank over, no start.
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.
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.
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!
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.
Fuel gauge and voltage gauges may not work or display properly.
You sometime will have No Bus on the odometer after 30-60 seconds.
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.
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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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.
2000 Sport 4X4 4.0 inline six, AW-4 Automatic, stock
Original Owner 300,000 miles
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.
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.
99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche Without "data", all you have is an opinion!