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Old 12-22-2012, 07:23 AM   eBay Motors  #1 (permalink)
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cam sensor troubleshooting

i have an active code P0340 for the cam sensor.

i replaced the sensor and i still dont have any rpm.

i checked the signal circuit at the ecm and its not showing any pulse so i replaced the cam connector and ran a new wire to the ecm for the cam signal. still no rpm. is my new cam sensor bad.

i started over with my circuit tests, heres what i got using the gm flow chart.

is voltage between 12v ref and low ref over 10v? yes 11v
is the voltage between signal and grnd 0v? it was .1v (close enough to say yes?) if its a no then it could be the ecm
is the signal at the ecm showing 45-55% duty cycle while cranking? no, 0 hz, 0 rpm, 0 duty pulse. but it shows 10v w the key on.

i really think my new cam sensor is bad. what do you guys think?
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Old 12-24-2012, 11:29 AM   eBay Motors  #2 (permalink)
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rpm is read off the crank sensor. The cam sensor is only used as a reference for the ECM so it knows which cylinder is at TDC.

I would take a look at the crank sensor as well. Remove the sensor and see if the reluctor wheel can be wiggled with a screw driver.
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Old 12-26-2012, 04:53 AM   eBay Motors  #3 (permalink)
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rpm is read off the crank sensor. The cam sensor is only used as a reference for the ECM so it knows which cylinder is at TDC.

I would take a look at the crank sensor as well. Remove the sensor and see if the reluctor wheel can be wiggled with a screw driver.
the code is P0340 which is a CMP DTC. there is no duty cycle from the CMP, could it really have to do with the crank sensor?
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Old 12-26-2012, 05:06 AM   eBay Motors  #4 (permalink)
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I will say crank sensor. They work together
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Old 12-26-2012, 10:39 AM   eBay Motors  #5 (permalink)
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the code is P0340 which is a CMP DTC. there is no duty cycle from the CMP, could it really have to do with the crank sensor?
it could; as bluecollar said, the CMP and CKP sensors work together. If the CKP sensor isnt reading correctly, it could cause the ECM to be "confused" with the signal that the CMP sensor is reading.

Check them both...its easy to check the CKP sensor and CKP reluctor wheel.

Ben
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Old 12-26-2012, 11:24 AM   eBay Motors  #6 (permalink)
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ill check both reluctors tonite and look at the CKP.
but just to make sure everyones clear, im not getting any signal from the CMP. i have the CMP signal wire pin removed from the ecm, the ecm connector installed and the CMP connector installed. while cranking i have 0% duty cycle from the CMP signal on my DMM using both the HZ and RPM/Duty Pulse settings.
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Old 12-27-2012, 05:03 AM   eBay Motors  #7 (permalink)
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pulled the cam sensor back out and checked the reluctor, it was fine. tested the CKP harness, it was good. started to pull the CKP to check its reluctor wheel but it broke off. so that where im at now.
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Old 12-27-2012, 05:08 AM   eBay Motors  #8 (permalink)
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Sensor broke or reluctor wheel?
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Old 12-27-2012, 05:31 AM   eBay Motors  #9 (permalink)
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sensor
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Old 12-27-2012, 06:21 AM   eBay Motors  #10 (permalink)
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sensor
At least it wasn't the wheel...
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