2000 Sport 4.0 No Start

[labourgeoisie]

Hey, y'all!

I'd like a little help and advice as I'm pretty out of my element here. I've got a 2000 Cherokee Sport 4.0 4x4, auto trans, all stock. If there's any info else you need let me know. The past few months have been rough on the Jeep starting with the power steering pump exploding and being replaced. Everything has been fine for the past few months with the exception of the heat soak p0303 I get every now and then, but overall no real issues.

Jeep had been running great all week. Saturday morning I went to leave and I've been plagued by the no start issue.

Here's what I know:

When I turn the key it'll crank but won't start. Belt engages, stays powerful. Have recharged battery and everything.

When turned on, you can hear the fuel pump engage if you're standing at the back of the Jeep. Likewise, when I press down on the valve on the fuel rail I get spray. My tank was low (gas light was on) but I put extra in it, just in case. Tried starter fluid. It gets a little closer to starting up but ultimately sputters out and dies.

Spark plugs were put in new a couple of years ago. Took them out and cleaned them up. #3 was pretty dirty (assuming because of heat soak?) but ultimately they all look fine. Have had serious frustration removing the connector on the inline ignition coil rail so haven't actually hooked it up to a multimeter--tester ordered on Amazon tonight to verify I'm getting spark.

I have tested/switched ASD relay and fuse to no difference.

I have traced what I believe to be the Crankshaft Position Sensor, unplugged, and replugged it in to no difference. My gauges all work and I am not getting the NO BUS issue either. To access this, I found it was easiest to slide under the driver's side door. The connector I unplugged did have three prongs, so I'm thinking it was correct, but I could have been wrong?

I have a bluetooth code reader. It claims to connect to the ECU but was not reading any codes. After we unplugged a bunch of sensors on top of the throttle body I started to get a p0122 but I believe it's unrelated as it hadn't been triggered before and doesn't seem to cause a no start as far as my research can tell?

Currently, I'm at a loss of what to try next possibly until that tester comes in and I can totally confirm I'm getting spark. Right now I'm under the impression that since starter fluid helps I may have at least intermittent spark? Which suggests it's not the crankshaft position sensor but maybe camshaft?

I have tried to start the jeep multiple times throughout the day and at different temperatures, but it doesn't make a difference. Prior to this, I have not had any stalling or weak starts (with the exception of few heat soak issues but not for a few months).

Just looking for advice or where to go next. This jeep is the first vehicle I ever do any real work under the hood on so I'm relatively inexperienced.

In advance, thanks for all y'alls help!

 

[thatxjguy]

First thing's first. You need compression, spark, and fuel to get an engine going.

I would start by replacing (not just cleaning up) the spark plugs/coil pack, and then checking the fuel injectors to make sure they're all doing their job. I assume you probably already have compression.

I'd be willing to bet that since your fuel system is working it has something to do with spark.

 

[CompleteCherokee]

also make sure the injectors aren't cracked. As thatxjguy said, check for spark and fuel first.

 

[Tim_MN]

Only replace parts that have been tested and proved faulty. Throwing random new parts at an undiagnosed problem gets expensive real fast.

Start by testing the CPS for failure.

Test the battery and alternator, inspect the battery and starter cables for loose connections and/or corrosion.

Your description of the symptoms, makes it difficult to determine if you are having a CPS issue, or are having a low voltage issue. Testing will help determine which is the problem.

Perform routine maintenance 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 or connectors and replace as needed. Copper wires should be copper color, not black or green. Do the same for the grounding wires from the starter to engine block, the ground wires at the coil, and the ground wires from the battery and engine to the Jeep's frame/body. You must remove, wire brush, and clean until shiny the cable/wire ends and whatever they bolt to.

Jeeps do not tolerate low voltage, bad connections, or poor grounds.

Place your DVOM (Digital Volt Ohm Multi-Meter) on the 20 volt scale. First check battery voltage by placing your multi-meter's positive lead on the battery's positive post ( the actual post, not the clamp ) and the negative lead on the negative post. You need a minimum of 12 volts to continue testing. Next, leave your meter connected and take a reading while the engine is cranking. Record this voltage reading. Now connect your positive lead to the battery terminal stud on the starter and the negative lead to the starter housing. Again, crank the engine and record the voltage reading. If the voltage reading at the starter is not within 1 volt of battery voltage then you have excessive voltage drop in the starter circuit.

Typical voltage drop maximums:
• starter circuit (including starter solenoid) = 0.60 volt
• battery post to battery terminal end = zero volts
• battery main cable (measured end to end) 0.20 volt
• starter solenoid = 0.20 volt
• battery negative post to alternator metal frame = 0.20 volt
• negative main cable to engine block = 0.20 volt
• negative battery post to starter metal frame = 0.30
• battery positive post to alternator b+stud = 0.5 volt with maximum charging load applied (all accessories turned on)

Test the output at the alternator with your volts/ohms multi-meter. You should be measuring 13.8-14.4 volts. Load testing the alternator is still recommended.

Have your helper turn the ignition key to START while you tap on the starter with a hammer. If the engine starts, you probably need a new starter.

Have the battery, starter, and the alternator Load Tested for proper function in a test machine that applies a simulated work load. Handheld testers are inaccurate and will often pass faulty parts.

 

[labourgeoisie]

Only replace parts that have been tested and proved faulty. Throwing random new parts at an undiagnosed problem gets expensive real fast.

Start by testing the CPS for failure.

Excellent writeup--I'll get testing all that tonight.

The CPS failure test--is that just by going through the steps in that post that's floating around here and there about hooking up the multimeter to the B and C terminals on the CPS and checking for low resistance?

I unplugged what I believe was the CPS and touched my probes to the male prongs that go into the plug on the wiring harness. Not sure how reliably I was touching the prongs nor am I sure how reliable the multimeter is as it's a really cheap harbor freight one, but I got something like a .1 across B and C. I didn't put much stock into it or spend much time messing with it as I wasn't sure if I was touching the right pieces/performing the test correctly.

 

[Tim_MN]

The most likely cause of it cranks and cranks but won't start up is the Crankshaft Position Sensor (CPS) located on the transmission bell housing. Often this part is also referred to as the CranKshaft Position Sensor (CKP). CPS/CKP failure is very common. The CPS/CKP can stop working with no warning or symptoms and the engine will not run or the engine may randomly stall for no apparent reason.

Crank Position Sensors can have intermittent “thermal failure”. This means that the CPS/CKP fails when engine gets hot, but works again when it cools back down.

Symptoms-
- Starter cranks and cranks but engine won't start up
- Fuel gauge and voltage gauges may not work or display properly.
- You sometimes will have NoBus displayed on the odometer after 30-60 seconds.
- A failed CPS/CKP may or may not throw a CEL trouble code.
- No spark at the sparkplugs.
- Fuel pump should run and prime for 3-5 seconds.

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

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

-You should 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.
-Unplugging and reconnecting the CPS sensor where it connect to the main harness near the back of the intake manifold usually resets the ECU and if the jeep fires right up after doing this you can bet that the CPS is faulty and needs to be replaced.
-Exchange the fuel pump relay and the ASD relay with one of the other similar ones in the PDC to eliminate these relays as the cause of the no-start. Confirm that the fuel pump runs for 3-5 seconds when you turn the ignition key to ON.
-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?
-Inspect the wires and wire connectors at the O2 sensors on the exhausts pipe. A short circuit from melted insulation or from broken O2 sensor wires can blow a fuse and the ECU/ECM will lose communication.

If you buy a new CPS, get a genuine Jeep CPS, or the premium one from NAPA. Cheap crappy “Lifetime Warranty” parts are often out of specification or even failed right out of the box. They usually also have a shorter service life than better quality parts. Buy good quality repair parts and genuine Jeep sensors for best results.

You must also perform 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. Jeeps do not tolerate low voltage or poor grounds and the ECM/ECU will behave oddly until you remedy this.

Crankshaft Position Sensor Connector (CPS/CKP)
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CPS Testing
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 the 10K-or-2OK scale for this test.
3. The meter reading should be open (infinite resistance). Replace sensor if a low resistance is indicated.

TESTING PROCEDURE for 1987 –1990 4.0 L engines
Test # 1 - Get a volt/ohmmeter 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.

The 2000 and 2001 will have the CPS in the same location on the bell housing, but the wire connector is on the passenger side, near or on top of the Transfer case, not as shown in the diagram below. Simply follow the wire from the sensor to the wire connector.
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[CompleteCherokee]

great instructions and pics, will be saving that

 

[labourgeoisie]

Tonight I must have had enough determination to get the connector for the coil rail off finally.

As per my Haynes manual, I probed the green/orange wire on the harness and a ground and got 10v. Not sure if this is losing too much voltage--my battery is running 12+. Everything seemed good with the starter, but I've got some cleaning stuff on it's way anyways.

However, I am getting a consistent 1.4/1.5 resistance between the 1/2, 2/3, and 2/4 pins on the coil rail itself. According to the manual it should be something closer to .95-1.18 roundabouts. On coil rail failures is it common for the resistance to be out of spec but the same on every pin? Don't want to immediately jump to the rail being the problem if I just have a misreading/calibration. I do have a better multimeter arriving in the mail and also clips to help test the CPS if necessary.

 

[CompleteCherokee]

I'd suggest checking with the better quality meter before replacing anything else. Too many people use the cheap harbor freight meters, which I've found to not be that accurate. I started using one from my father-in-law (former electronics repairman) and saw quite a difference in accuracy.

 

[Tim_MN]

As per my Haynes manual......

Spend $6.95 for genuine Jeep service manual at PacificCoastManuals.com. Precise test procedures and exact test results will be found in the service manual.

Hayne and Chilton's are nearly worthless for anything more involved than tune-up, brakes, and oil changes. Not to mention they are full of both errors and omissions.

 

[labourgeoisie]

I'd suggest checking with the better quality meter before replacing anything else. Too many people use the cheap harbor freight meters, which I've found to not be that accurate. I started using one from my father-in-law (former electronics repairman) and saw quite a difference in accuracy.

Yes, it definitely made a difference. Went from 1.5 on the coil rail on the cheap multimeter to 1.0 on the better one.

Spend $6.95 for genuine Jeep service manual at PacificCoastManuals.com. Precise test procedures and exact test results will be found in the service manual.

I just did--awesome resource! Thanks. I was definitely questioning the Haynes manual at some points.

So, my coil resistance is at 1.0~1.1 when it should be .71-.88.

On the CPS B and C terminals my multimeter is reading 8. Since it's not open, I'll assume it's probably the CPS and that the coil rail is probably not the culprit and I'll begin with that.

Thanks for all y'alls help and patience so far!

 

[CompleteCherokee]

yep, a good meter is worth its weight in gold so you don't replace things that you think are bad, but are actually good

 

[labourgeoisie]

Just wanted to post an update, especially for those in the future who come across this and want to rule out their CKP because they're not getting NO BUS or gauge issues.

New CKP in and it came right up. I struggled alone for 3 hours but found it to be about 20 minutes or less with two people. I had enough extensions on to get past the crossbar while my help held the socket on from the top side.

Couple of issues now...the plastic shield the CKP points through came off of the throttle body, didn't realize it until after it was installed. Is it possible to slip this on without removing the whole thing again? Is it even necessary?

Before the change, we had unplugged a bunch of stuff from the top side) a few weeks ago looking in absolutely the wrong place for the CKP, that seemed to have triggered a P0122. However, more pressingly, I'm getting a P0351 and P1391. I'll try to reseat the connections but I'm wondering if there's a bigger issue at play. Maybe my coil got messed up while I was twisting it around so much and since I left it sitting out off the jeep for a week. I was curious as to if the intermittenent loss of CKP code could be caused by interference from not having the plastic shield on the housing of the throttle body?

First drive after CKP replacement went fine, though it was having a really rough idle. My dad went to take it to his house and turned around on the interstate because he said it was starting to miss pretty bad when he gave it gas. Going to start by making sure the spark plugs have been put in securely and then inspect the coil rail connection.

 

[Tim_MN]

Reset the PCM and then deal with any Trouble Codes that return.


This very simple procedure will erase the 1996-2001 “Adaptive Memory” stored inside the PCM and allow a new “Adaptive Memory” to be developed. After performing this procedure the 1996-2001 PCM will re-learn and store into Adaptive Memory your engines performance characteristics. Perform these steps exactly as they are written, in the order they are written. This will cause the adaptive memory in the PCM to be erased and cause the PCM to go into Fast Learn adaptive mode.

Disconnect the POSITIVE battery Terminal clamp and touch it to ground ( not the battery negative terminal ) for 30 seconds. The engine block or the A/C compressor pump will work as a ground. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory).

Reconnect the Battery Cable
Turn Ignition Switch to the “On” position but DO NOT start the engine
Turn Headlight “On”
Turn Headlights “Off”
Turn Ignition Key “Off”


The PCM Adaptive memory has now been flashed, or erased from the PCM. When you start the engine it will be running off a set of pre-programmed tables that come with the PCM from the factory. When you get the engine up to operating temperature the PCM will start to collect data for the “Adaptive Memory”. The PCM will collect data for Adaptive Memory for the first 50 Warm-up Cycles.

 

[Talyn]

Couple of issues now...the plastic shield the CKP points through came off of the throttle body, didn't realize it until after it was installed. Is it possible to slip this on without removing the whole thing again? Is it even necessary?

You mean the CPS? And the bell housing? Judging from your description of the install I'd say you replaced the CPS (crank sensor), not the CKP (cam sensor). On the shield I believe there is a small piece of plastic that should go between the CPS and bell housing. That may give a bit of a problem putting the shield back on. You may consider cutting that small piece and slipping the cover back one.

 

[labourgeoisie]

You mean the CPS? And the bell housing? Judging from your description of the install I'd say you replaced the CPS (crank sensor), not the CKP (cam sensor). On the shield I believe there is a small piece of plastic that should go between the CPS and bell housing. That may give a bit of a problem putting the shield back on. You may consider cutting that small piece and slipping the cover back one.

Yes, it was the crankshaft, and yes, it's the bellhousing. I'll have to give it a try. Good idea about cutting the plastic. That should work perfectly.