1991 Jeep Cherokee won't start

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Apr 5, 2012 | 08:03 PM
  #16  
You will get no spark or injector pulse with a bad crank sensor.
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Apr 5, 2012 | 09:15 PM
  #17  
Hey another thing is that your new crank position sensor could be bad. The cheap "auto parts store" cps's sometimes are bad right off the bat. Here's a test procedure.

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 will 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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1991 Jeep Cherokee won't start-image-596585321.jpg  
 

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Apr 5, 2012 | 09:59 PM
  #18  
X2 on the cps sensor... replaced the one on my jeep with one from autozone was bad out of the box didnt know and changed a bunch of sensors that didnt need to be replaced got a another one bad out of the box again went to chrysler and got it havent had a problem since completely worth the couple of extra buck
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Apr 6, 2012 | 09:50 AM
  #19  
Quote: Crank sensor.

Already replaced. But in theory, I should be able to test the sensor off the vehicle but moving it close to metal and then further away. Does this sound accurate?
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Apr 7, 2012 | 12:14 AM
  #20  
Quote:
Already replaced. But in theory, I should be able to test the sensor off the vehicle but moving it close to metal and then further away. Does this sound accurate?
From chrysler? That really doesn't test it. Yes it's a magnet but thats not really what goes bad. If it is a Chrysler crank sensor then you should check resistance in the wires to the crank. Or you can test the sensor with a ohm meter in which I believe a good one will have 5 ohms of resistance. Dont quote me on that. If you have a meter test the wires to the crank key on engine off. The crank runs off a 5 volt reference. You should see 5 volts. Or you could also get a headlight bulb if no meter and rig it up to with two wires and put each wire in the pins that's hook into the sensor and with key on engine off the light should illuminate brightly. If you live close to me id give you a hand. I can show better then tell. Haha
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