Hello my name is Dennis new to this forum but not to others. I have used the search but with no luck to my ? I have a PO335 code rpms hit 3,000 and tach goes crazy scanner says the rpms hit at 12,800 only code is the PO335. ANY help would help

 

That's P-zero-three-three-five. Not P-O-3-3-5.
P0335 - Crankshaft Position [CKP] Sensor A Circuit

You have a CKP sensor issue.

I would take a look at either of these two diagnostic charts and see what you can find with a multimeter, etc.
P0336 - CKP (crankshaft position) Sensor Circuit A Range/Performance
P0339 - CKP (crankshaft position) Sensor Circuit Intermittent

 

Excuse me for my type-o we have checked all voltage everything has 12v ref. The only thing we did was replace lower intake gaskets. and problem popped up. no loose ground wires.

 

Did you ohm the wiring between the PCM and the CKP sensor? While moving the harness around?

 

Yep, and no change

 

What were the ohm readings on the wiring between the CKP sensor and the PCM terminals?

How about those diagnostic sheets? I seriously doubt you have gone through it all and found nothing...

 

I dont remember my brain is fried trying to track this down

 

Do you remember the airgap between the CKP sensor and the reluctor ring on the crank? Or did you check that? If the CKP sensor is too far from the reluctor ring, it can cause erratic readings.

Also, a dirty CKP sensor can cause erratic readings.

 

I am working exactly the same issue on my friend's 2001 blazer. Idles perfect. Starts like a champ.

When the trouble started my friend replaced the CKP sensor...no change. He did a complete (wires, cap, rotor, plugs) tune up...no change.

Since I've been playing with it:

I've checked the new CKP sensor for rub marks and found none. The gap doesn't appear to be adjustable except for using a shim, and since it's not rubbing I don't think it needs a shim.

I've buzzed out the wiring between the CKP and the PCM and it checks...zero ohms. Yes I shook the wiring while testing and all looked fine.

The TPS tested bad so I replaced it... no change

The threaded ears on the distributor were broken off and cap was rotating on it's own...ACK! I found some j hooks and that seems to secure it fine. But still ....no change.

I replaced the PCM...no change.

I read somewhere that the distributor gear in the 4.3L tends to fail frequently so, I'm puling the distributor next.

This motor has 100K plus miles on it so, I suppose it could also be a timing chain or a cam position sensor.

I don't have a fancy scan tool...just a basic reader.

Now, the original poster on this thread changed a head gasket. I wonder if a compression issue can cause this code?