Guys I've got an 05 2500 HD truck that sets p0341 cam sensor code on start up, it always starts has had a new OE one installed Ive even wired directly to the pcm from the sensor bypassing the stock wiring and still sets the code. Crank reluctor is ok Iget a good signal on the scope and the tdc on it and the crank sensor line up on the scope. Have also tried another pcm same result. Once when i first wired it direct the code stayed off but then came back. Rather frustrating, any ideas from anyone here. Any of you have a screen shot of known good cam sensor signal?
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I'm guessing that it's a GM (duramax-?)and it's possibly a 6.6-?? diesel.
Adding the VIN also helps.
Have you by chance had a look at the SI for that code, what the circuit operation is, what they suggest for testing-?
If SI indicates what is required for setting the code, check those parameters.
Sorry I'm not much help but being more specific identifying the vehicle might help someone else identify things or jog their memory.
If it is a diesel, what does it require for signal voltage supply, and could the voltage be dropping below the threshold when the heavy load of cranking a diesel occurs-? -
Cam sensor is hall effect ? 3 wire ? Check the pins in the harness at PCM ? Is some thing pulling the voltage or ground away from the PCM ?Comment
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My guess is the problem might occurs during high amperage load of cranking and it's just about getting to stage that it could cook your chassis grounds and become a slow or no crank. Some times if I'm too lazy to do a voltage drop test , I'll use good set of jumper cables from the battery neg clamp to a clean metal on the block to supplement a suspect negative battery cable to carry the current from the block to battery, so it don't try to back feed through the smaller chassis grounds.Comment
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Is this a high mileage engine, 250,000 or more?
I would check the air gap between the reluctor wheel and sensor. that wheel is attached to the camshaft and has a thrust plate that control's the fore and aft movement of the wheel/camshaft, it can wear enough to change the gap on start-up. this happens on start up because the oil bleeds away from the thrust plate when you shut it down. when you start it, it takes just a second for the oil pressure to move the cam/reluctor wheel into place. just enough time for the cam sensor to miss a count. have you scoped the sensor while cranking after a shut down?Comment
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Maybe could skin the cat cheaper without a tear down , and shim out or take .010 off the mating surface of the old cam position sensor, depending whether or not the thrust washer wear problem has caused sensor to get too close to the ring or the gap between the two has increased and become too large.?
Not too confident it would work. I've seen some crankshaft endplay become ridiculous enough on a few older manual transmission equipped Ford Escorts or Focus that they would lose the Crank shaft sensor signal,
Maybe Dorman could make custom ecentric adjustable ones for camber, caster, and toe to find where the tone wheel alignment might be.
LMAO
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resources.bmp
when you scope the cam sensor the frequency will change with rpm"s, this is normal. look for one or more frequency humps to miss or not be there. take a start-up scope capture, if you don't see anything obviously wrong use your cursors and measure the delta time between each start of the frequency humps. make sure they are all the same.Comment
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05 lly 6 speed manual silverado. It sets as soon as it starts which makes me wonder about voltage. It only ever shows 1 missed cam count on the datastream always while it's starting goes to zero after even when I wiggle wiring around. Has 145k on it I wondered about sensor to wheel clearance as well. I have 5 volts at sensor pretty steadily and see a nice pattern at the pcm. I'll try to post screenshot on here if I can of cam sensor pattern thanks for the suggestions so far. I'm usually the go to guy in my area for this kind of stuff but this ones bugging me and sometimes all it takes is a fresh perspective to see something wrong.Comment
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