jalfaro

Hello everybody. I'm stuck and could sure use your advise. Changed the timing cover and changed the oil pan gasket since it has 220,000 miles. I used the old crankshaft position sensor. After putting everything back together, I get one time weak spark at initially cranking, then no spark. I checked spark at ignition coil and get same (One time Weak spark, then no spark). My code reader is saying P0336. I checked the plug at the sensor ground is good. Volt supply shows 12 v. Sensor signal was 10v. I put in a new CKP sensor and with that one I get no spark.
Your advise is highly appreciated. Thank you.

oldchevy

Check the harness to the CKP for any damage. If all is good, I wood replace the CKP.

jalfaro

I checked the harness everything looks good. I tried it with a new CKP sensor and absolutely no spark. When I put the old CKP sensor I get a quick initial spark, then no spark.

jalfaro

I checked the harness everything looks good. I tried it with a new CKP sensor and absolutely no spark. When I put the old CKP sensor I get a quick initial spark, then no spark.

kevinkpk

Is the sensor the probe, or half horseshoe? Either way it has a magnet, might be the new sensor is just bad, and the old sensor magnet is weak. I've had on my car the magnet weak, wouldn't pick up small screws, also if you have an ohmeter check the coil. The old sensor could be breaking down if it checks good, the new sensor may just be bad. I've had electrical parts returned that had been used (autozone, spark plugs) my guess is resistance should be around 800-1200 ohms.

jalfaro

Hello everybody thank you for advise! I really appreciate your input.

Here's the latest. I conducted Crankshaft Position Sensor Test:

1.Back-probed the harness with multimeter while it was connected to the sensor to check if I had 12 v running through on the top wire. Confirmed
2. Back-probed with multimeter the middle wired (ground) to confirm ground was good. Confirmed.
3. Back-probed bottom wired (signal wire) to confirm I was getting 5 v pulse. (This test didn't react how I expected!)
When I turn the key to Run/On (Not Start) multimeter displays 5 v pulse. I can here a humm. If I turn the engine over manually with a ratchet, the humm goes away and I can hear the release of fuel. Then the 5 v pulse goes away. No matter how many times I TURN OVER THE ENGINE I can't get the 5 volt pulse back

This makes sense to me because when I did a spark test at spark plug, I would get one first spark and that's it. When I did the test at the coil, same thing would happen.

With my CKP sensor I wasn't getting any signal. Good ground and good 12 v, but no pulse, I suspect maybe because it was rubbing. I ordered a shim for the new sensor and going to conduct the same test with it today.

Thanks again everybody for your input! This is my everyday truck and the time you take to answer my questions does not go unnoticed!

oldchevy

If the sensor is rubbing, you must have the wrong sensor. Double check your part numbers.

Lilroud

There was a service bulletin released on this motor years ago where crankshaft wear over time can cause the sensor to be scraped and gm advises to shim it if there are witness marks... but ONLY if there are witness marks on it.

oilcanhenry

Potential causes of a P0336 code includes: Bad crank sensor ,Broken reluctor, ring (missing teeth, debris lodged in ring) ,Reluctor ring dislodged/stripped from it's stationary location Wiring harness chafing causing short wiring open in CKP circuit. Could also be bad ECM/ PTM as well.