LS Engine gurus chime in PO335 - Z06Vette.com

**seamus2154** · 11-19-2012, 09:46 PM

I know one of you motor heads may know what this means or is leading to. My 2007 GMC sierra 5.3 w/ active fuel management popped an engine light today. After over 6 years of faithful service and after I just told my Dad today that I have never had a problem w/ this truck it's flawless....it sends me this engine light!!!!LOL So I plug in my scanner and come up w/ PO335. Crank sensor. Truck runs fine. I did just do plugs a week ago and one wire pulled off the boot. The core wire was fine and I folded it back and pushed it back into the boot. Ran fine all week. So I figured why buy new wires if i get a misfire in one cylinder I know what it is. It is my understanding if the crank sensor is bad you get a crank no start. She is running and starting. I cleared the code and it didn't [pop back up yet?? Haven't driven it though. Is this an indication of something that is going?? All stock no tune or modifications. 71,000 miles meticulously cared for. Thanks Guys!

**seamus2154** · 11-20-2012, 08:03 AM

I just had it out on a two hour drive. No light no issues??? Any thoughts?

**itsaz** · 11-20-2012, 08:37 AM

How old is the battery?

**seamus2154** · 11-20-2012, 08:46 AM

less than a year old, no issues.

**itsaz** · 11-20-2012, 08:48 AM

OK, that's the first thing the service manual says to check.

racingvette · 11-20-2012, 11:56 AM

You need to use a OBD scanner and capture the freeze frame as that would tell exactly what the PCM saw as that DTC triggered.

Even new battery can have a weak cell so always do a full battery load cell test as voltage or ground issues can cause odd tripping error code

The error means the PCM so no signal for CKS for less then 4 seconds.

There should be 3 wires to the sensor, 12V, ground and sensor output
Check connector for clean, no bad pins or cut wires.

Sometimes a stretched timing chain can cause this

Check to see if any amount of misfires reported via scanner

**seamus2154** · 11-20-2012, 05:49 PM

No misfires, no other codes. Because of that pulled wire I was expecting a misfire, but no. It is running great today but I will get under there and make sure no rodents are nipping at my wires and all is clean. I have owned since new and am a maintenance nut. Truck is almost like new. Synthetic oil changes every 5K-7K. You think I could have a stretched timing chain???

racingvette · 11-21-2012, 09:38 AM

If I read this right you pulled 1 sparkplug wire off while engine was at idle and no misfires or P0300 DTC ?

If CKS was bad and PCM could not see any signal from it then it also would not know CKS position to CAM sensor position and engine would run like crap and have a hard time starting

IF CKS wiring pins dirty, loose connection, maybe then there is a very short timeframe ( under 4 seconds) PCM sees no signal but not long enough to cause misfires.

Well maybe due to weak cell of battery, loose,dirty ground splice pack or dirty pins on either CKS or even at PCM side.

Else one of the 3 wires got nicked and temp shorts to ground

Try to induce it while connected to a scanner and watch the "current" misfire counters along with the CKS parameters so pinpoint if real issue or wiring or voltage issue

**seamus2154** · 11-21-2012, 04:44 PM

No, I didn't pull the wire off while running. When I changed the spark plugs last week one boot pulled off the spark plug wire. The core wire was exposed and I folded it over the insulation and reinserted it in the boot and crimped. I expected maybe a misfire and then I would buy new wires if so. It never happened. But this week I got the po335 code. I have to get under there and check the condition of the wires and plug at the CKS. It ran fine again today. ?? Thanks for your help and opinion!!