1999 jeep cherrokee sport no start - JeepForum.com

 
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post #1 of 9 Old 10-26-2009, 10:56 PM Thread Starter
link4889
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1999 jeep cherrokee sport no start

hey guys so i have a 1999 jeep cherokee sport ran fine till friday morning. it drove fine thursday night went to start it friday morning and all it did was crank. ive heard the the crank shaft postion sensors and coils go bad alot. its got 108,000 miles on it. any tipes where to start looking or ne fixes or anything would be a great help thanks for your time guys. tom

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post #2 of 9 Old 10-27-2009, 12:28 AM
CJ7-Tim
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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 (and will test as “good”) when it cools back down.

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 starter to engine block, and from the battery and engine to the Jeep's frame/body. Jeeps do not tolerate low voltage or poor grounds and the ECM/ECU may behave oddly until you remedy this.



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

If the CPS/CKP is failed sometimes an OBD-II trouble code reader cannot make a connection to the ECU/computer or cannot read Check Engine Light/MIL codes because the CPS/CKP has failed. Disconnect the code reader, disconnect the CPS/CKP wire connector, and reconnect the code reader. If the code reader establishes contact with the ECU and scans, your CPS/CKP is failed and needs to be replaced.


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 the relays as the cause of the no-start. Confirm that the fuel pump to 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 loose communication. Don’t get tunnel vision and assume the sensor is bad (unless it tests ad with a meter). Damaged wiring or a dirty connector can inhibit the signal from making it to the computer. Check/clean/repair wiring or connectors as necessary.


CPS Testing


Crankshaft Position Sensor Connector (CPS/CKP)





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.


The 2000 and 2001 will have the CPS in the same location on the bell housing, but the wire connector may be on the passenger side, not as shown in the diagram below. Simply follow the wire from the sensor to the connector.

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post #3 of 9 Old 10-28-2009, 09:17 PM Thread Starter
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thanks buddy i did all the tests u listed and its not the cps. i did a spark test tho and im not getting ne spark. so im heading in the coil direction
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post #4 of 9 Old 10-29-2009, 12:45 AM
CJ7-Tim
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Coil or the Camshaft Pickup Sensor in the distributor.

.

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post #5 of 9 Old 10-14-2010, 02:46 AM
rmpjeep99
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Well sounds just like my problem same jeep and year, other than that i just put in new spark plugs, wires, cap, rotor i had spark but i was still cranking soo that didn't solve my problem..soo i suppose it maybe my cps then..cause usually the hot days would cause problems especially lately its been 90 and up over here in cali and sometimes i would crank when i would start my jeep eventually the heat just made it worse on the cps im sure.
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post #6 of 9 Old 02-15-2012, 12:59 PM
danzeger
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I too am having the same issue. I have a 1999 cherokee sport, will not start. Cranks fine, no spark from the distributor. I have replaced the coil, the bell housing sensor and the plate below the distributor cap. Still will not start. Any ideas? Any help will be much appreciated.


##UPDATE##

After a week or so of troubleshooting and replacing parts, it turns out I had a bad relay switch. This switch is located in the fuse box, unfortunately there is no way by looking at it to tell that it is bad. Through a lucky turn of fate, I was introduced to an honest former Chrysler mechanic who now runs his own shop and had his own PCM diagnostic tool, he connected it, got the readings and said the relay switch wasn't sending signal to the computer. All in all, switch and labor cost me fifty dollars. My Jeep is back on the road and running great. Hope this helps anyone out there with this issue.

Last edited by danzeger; 02-28-2012 at 01:00 PM.
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post #7 of 9 Old 12-26-2013, 10:24 AM
stevexj99
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Hi everyone I'm new to the jeep forum. I'm trying desperately to solve my own issues with my '99 Cherokee. It will not start as I have seen to be a common problem with them. I have changed the ignition coil which seemed to work. I went out the next day and it just cranked with no dice on starting. I changed the cps still no start. Wonder which relay switch to check in the fuse box. Also horn and radio not working. Wondering if this is all related. I am getting fuel as well and the pump is engaging when the ignition is turned on.
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post #8 of 9 Old 10-19-2016, 12:45 PM
Mongolia
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Hello,
My 1999 Jeep Cherokee will not start. I've chased down all the previous mentioned issues. Tested all the relay switches and fuses. Not the issue. Changed out the distributor cap and ignition coil. Still struggling to get it running. Fuel pump is working fine...can hear it when I go to start the engine however, it never cranks over. Any tips on what else to try....or can give me a hint on where to find the CPS sensor on a 1999? I can find it in the book and on line in every year but the 1999.

Thanks,
BH
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post #9 of 9 Old 10-19-2016, 09:25 PM
dzywicki
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The CPS is at the union of the transmission bell hosing and the engine on the drivers side. Replaced the one on my 99 last year. Found it was easier to do it from above. IIRC, I used a long ratchet extension from underneath to loosen the bolts and then finished getting them out from above with my fingers. I ended up using echlin from NAPA (same for the cam position sensor) and haven't had any problems.

https://www.2carpros.com/questions/j...ition-sensor-f
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