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No spark - crankshaft position sensor shows 0 ohm on PCM pins 46 and 47 on connector C175E


lalondem_98

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I changed the 3.5l  using a  2010 engine installed into a 2010 ford Edge, I re-used my wiring harnesses, I fixed 3 coils connectors (due to locking tab broken), i fixed 1 camshaft position connector (due to locking not working, I removed and re-inserted the sensor).  The engine started a few times for a few minutes and died suddenly and softly (no noise or explosion!).  Now I cannot start it anymore, I pulled out one spark plug and I have no spark when I ground the bottom electrode.    When the engine dies the battery voltage is around 12.2 volts, the alternator is new and my Dewalt battery charger says the alternator is good.  Any idea?  When the engine ran for a few minutes it was always smooth and quiet, not rough or noisy (I had a big smile on my face that vanished when it died!)

 

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Thanks for your reply, I am using Forscan, the PCM self-test with the ignition key ON and engine OFF would be good but it does not go too far as it encounters problem with the IAT (Intake Ambient temperature)...let me check into that.  For the alternator it is a rebuilt one, not an OEM.  For now my question would be: what can cause a no-spark condition at an individual spark plug if the individual ignition coil is good?

 

 

 

image.thumb.png.90e8648a2c475f358b64057bf6d23c06.png

 

 

 

 

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Clearly the alternator isn't working and its possible that could be causing some or all of the issues preventing the engine from running when the battery drops too low.

 

Those codes would not prevent it from running.

 

Is the power to the coils with just the ignition ON ?

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19 hours ago, 1004ron said:

Clearly the alternator isn't working and its possible that could be causing some or all of the issues preventing the engine from running when the battery drops too low.

 

Those codes would not prevent it from running.

 

Is the power to the coils with just the ignition ON ?

Hi 1004ron , yes there is power (12V) to the ignition coils with the key in ignition on and the engine off....I tested the 3 in front of the engine, will do the back ones later if needed.  My next test is to have someone turn the key to run so that the engine cranks and the second wire at the ignition coil is supposed to be "commanded" to ground by the PCM.  You had a good point...and I expect that the PCM will not "command" the second wire leading me to think that either the PCM is defective or the PCM has a "reason" not to command any of the coils....

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  • 3 weeks later...

Ideally I would like comments from people that have first hands experience on having a crankshaft position sensor reading 0 ohm between its 2 pins.  My engine cranks but does not start and none of the cylinders has spark.  I measured the resistance across the two pins of a spare crankshaft position sensor and it reads 675 ohms; I unplugged the PCM connector C175E and the resistance across pins 46 and 47 (CKP+ CKP-) is 0 ohms (a short).  According to AI (but I prefer getting the info from a human) :

 

The expected bench resistance of the Walker Products 235-91372 crankshaft position sensor when it is unplugged should be between 400 and 800 ohms (up to 2,500 ohms max depending on ambient engine temperature). [1]

...

Faulty (Short Circuit): If your meter reads 0 ohms or near zero, the internal insulation has failed, shorting out the coil.

 

I will remove it to confirm the short ; its location is terrible that's why I probed using the connector disconnected.

Edited by lalondem_98
lacked explanation
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  • 1004ron changed the title to No spark - crankshaft position sensor shows 0 ohm on PCM pins 46 and 47 on connector C175E

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