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sprinkles08, ASE Certified Technician
Category: Jeep
Satisfied Customers: 22827
Experience:  Chrysler/Dodge/Jeep Master Certified, ASE Master and Advanced Certified, Trans and Hybrid Specialist
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2000 jeep grand cherokee se: wont start..guages..I put a rebuilt..PCM

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My 2000 jeep grand cherokee won't start, it turns over but won't start. The guages will not read anyting. I put a rebuilt, reprogramed PCM in and still the same nothing. I have a OBD ll scaner and will not read anything. It says unable to link. Can anyone please help me?

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When this happens, the pcm is down. It could be the controller itself (not likely since it was replaced) or an outside electrical problem that is taking it down. A lost power or ground feed to the module, a sensor ground circuit shorted to voltage, or a reference voltage circuit shorted to ground will all cause the engine controller to go down. You will have no spark, no fuel pressure, the fuel gauge and voltmeter on the dash won't come up with the key on. There won't be any communication with a scan tool because the pcm is dead to the world. A common cause for this is an internally shorted crank position sensor. This is mounted at about the 11:00 position on the bellhousing as viewed from behind, and the electrical connector comes up to the back of the intake. Start by unplugging the crank sensor and see if the fuel gauge and voltmeter come up. If they do, replace the crank sensor. If this doesn't make the gauges come alive you'll need to do some deeper electrical testing to see why the controller is down. I would start with the powers and grounds, then move on to the reference voltage and sensor ground circuits. I can help you with that if you've got a voltmeter and want to get into some testing while it's acting up.

Customer: replied 7 years ago.
I'm going to go out there right now and see if i can find it and try to unplug it
It's a three wire connector, something I forgot to mention in my first reply. There may be another four wire connector in the area, this is an oxygen sensor. Good luck - I'm betting this will be it. It's pretty common.
Customer: replied 7 years ago.
I pulled the 3 wire connector off and still nothing. It is the one that pops right off correct? the one with latch and it is on the tranny?
graphicNo, the crank sensor connector is at the left rear corner of the intake. The sensor mounts to the bellhousing at about the 11:00 position as veiwed from behind. It reads off a tone wheel on the flexplate, in front of the torque converter. You'll unplug the crank sensor from the engine compartment. Look at the back of the intake, you are looking for a black three wire connector. It will be near the firewall, somewhere close to the end of the fuel rail normally.
Customer: replied 7 years ago.
Ok let me go out there again.... I'll look again



Customer: replied 7 years ago.
sorry i'm still looking not seeing it for some reason

The sensor is mounted at the bellhousing, the pigtail comes up into the engine compartment and is at the back of the intake manifold. There isn't another three wire electrical connector in the area. Have you found the sensor from my last diagram? The sensor should be easy to spot from underheath with a flashlight. Once you find the sensor and know what area it is in you can see which direction the wiring goes to know where to look from the top side. On the older 4.0 the connector ended up on the right side of the engine block near the distributor but that should not be the case with yours. Find the sensor and you will be able to see which direction the pigtail goes for sure and you'll find the connector.



Customer: replied 7 years ago.
I looked on the left side and did't find anything I looked over to the right and saw a 3 wire connector and pulled it off. the guages came back!!! Man you are f**ken awsome thank you so much. So i should replace that and it should start. Do you know what is the ball park price for those?
Great!! I would recommend a Mopar sensor from a dealer over an aftermarket one. I've seen too many problems with even brand new aftermarket sensors than to ever use them. The sensor at a dealer will run you $110, you can get one from for $75, the same factory part.
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