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joe, ASE Certified Technician
Category: Car
Satisfied Customers: 639
Experience:  ase certifed technician foreign and domestic
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1999 Jeep Cherokee Classic: service engine light came..wont start

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Have a 1999 Jeep Cherokee Classic with a in line 6 cylinder 4.0. Last week it wouldn't start all the time so service engine light came on and read the code, P0340, with a scan tool and it came up with Crankshaft/Camshaft position sensor. I replaced it Monday and it ran fine until yesterday I had the same issue, turns over but wont start and service engine light came on.

I got code P0340 and P1391. Could the CPS good bad that soon? Also I got a Haynes Repair Manual and Code P0340 is not in it. I get a desription on my scan tool and P1391 is different than the manual description. Scan tool has Manufacture control ignition system or misfire and manual has Intermitten loss of either camshaft or crankshaft position sensor.

does this vehicle have a distributor?

Customer: replied 7 years ago.
Yes it has a distributor. It is a inline 6.
ok at this point I would replace the ignition coil, sometimes one item will cause too codes, because it feeds two or three other sensors, so I would go with the ignition coil, then we can take it from there. if necessary
Customer: replied 7 years ago.

Is there some way to check the ignition coil?



yes you will need to get a multimeter or voltmeter, first you'll want to check if your getting the twelve volts you need going to it, then you will need to test the output voltage, this is not something you should do yourself .if you know someone that can do it for you then go ahead and have them do it, I think autozone can test the ignition for you for free. not positive, its work a call.

Edited by joe on 9/27/2009 at 2:27 PM EST
Customer: replied 7 years ago.



I started the jeep up this morning and drove it to my place and I thought the coil either worked or didn't.

yeah but it could be intermittent, no engine light either? check all the spark wires and you will need to check if you have fouled spark plugs too
Customer: replied 7 years ago.



Back to my original question, why is the repair manual codes and scan tool descriptions different. P0340 is not in the manual and p1391 in the manual points to crankshaft position sensor and scan tool points to ignition system and miss fire.

crank position sensor is part of the ignition system, and can cause a missfire.
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