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Juan Crespo
Juan Crespo, ASE Certified Technician
Category: GM
Satisfied Customers: 1513
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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I got 2009 gmc savanna 6.0 it runs but has no rpm pulse and

Customer Question

hello I got 2009 gmc savanna 6.0 it runs but has no rpm pulse and has code p0335
Submitted: 9 months ago.
Category: GM
Expert:  Juan Crespo replied 9 months ago.

This code sets when the PCM does not detect a crank signal - the 6.0L engine can still start and run on cam position and intake air flow. It'll just take longer cranking times to start.

P0335 is a crank position sensor circuit signal missing code and it's best diagnosed starting with a thorough visual inspection of the sensor, its connector and the wires going to it. If that doesn't reveal the fault, then a scope is recommended to test the actual signal.

Customer: replied 9 months ago.
I put new sensor and wire conector from dealer still same,i just change the engine with reman.
Customer: replied 9 months ago.
what scope test
Customer: replied 9 months ago.
I have no pulse I tested the wire and one has grount middle one and both has 5 volts
Expert:  Juan Crespo replied 9 months ago.

What tools are you using to test this?

Customer: replied 9 months ago.
just the snap on scanner
Expert:  Juan Crespo replied 9 months ago.

I'm not familiar with that scanner, but if it's equivalent to a Tech-II, then it should show crank speed on the list of PIDs. Does it?

Customer: replied 9 months ago.
I have the feature but no rpm
Expert:  Juan Crespo replied 9 months ago.

OK then, your scan tool has done its job, it's just that the signal is either not getting to the PCM or the PCM can't process it.

If you don't have access to a scope (much much cheaper than most good dmm's), then a very fast digital voltmeter might be able to pick up the RPM signal from the White/Black wire at the sensor. If there's no signal, then the reluctor ring on the crank might be missing. I've attached the sensor connector graphic for your reference. Please let me know what you find.

Customer: replied 9 months ago.
good morning I ck the wires fromt computer and im getting ground,5 volts and no pulse
Customer: replied 9 months ago.
I ck the reluctor it is fine it is the same as the old engine
Expert:  Juan Crespo replied 9 months ago.

OK. This is where we are with this issue: PCM says there is no crank signal; your scan tool says the same; you say reluctor is fine.

What does that leave us: possible faulty crank sensor, possible open circuit in sensor or PCM connector, possible open circuit in harness from sensor to PCM, possible faulty PCM.

How do we find out: we start by checking whether or not the signal is getting to the PCM at the White/Black wire going to PCM connector X2 terminal 68. If the signal is getting there, then the PCM must be bad. If the signal is not getting there, then we go back to the crank sensor connector and test there. If the signal still isn't there, either the crank senosr itself is bad or it is not being triggered by the reluctor ring.

What tools do we use to test the signal: best tool is a scope; second best is a voltmeter that can read frequency in Hertz (Hz). Don't have either one? How about rigging a Noid light?

In other words, my friend, I have the technical knowledge and experience to help you diagnose this issue and most of all, I really really want to help you, but it is up to you to get the tools you need to do this.

Expert:  Juan Crespo replied 9 months ago.

Attached please find a graphic showing PCM connector X2 for your reference.