2008 Tundra - P0335 & P0339 Fault Codes

I need help!!!! I have a 2008 Toyota Tundra SR5 4WD 5.7 Litre 3UR-FE


The truck bucks and stalls with Fault Codes P0335 & P0339 Crankshaft Position Sensor "A" Circuit and Crankshaft Position Sensor "A" Circuit Intermittent. I have replaced the Crank Sensor twice with a Toyota Sensor. The customer brought me a Re-flashed ECM he got from a company on the Internet that specializes in Engine Computers. You send them your VIN and they program it for you. I haven't done a Crank relearn because my Snap-on Triton Scan Tool does not have this function. The truck was fine for awhile now the problem has returned with a vengeance. I have scoped the Crank sensor pattern, and the V-Ref signal. The crank signal goes away as the engine stalls and the Fault Codes return. V-Ref remains steady. It is like the signal is not being pulled to Ground. I have attached A picture to this Thread. I have checked the signal at the sensor and at the ECM. I have done a major harness wiggle test, and I have checked the connectors for corrosion. The only thing I haven't done is strip the harness down and pull the trans to check the Trigger plate, but the signal doesn't give me any indication there is something wrong with the Trigger plate. The truck does not qualify for the updated harness from TSB-0220-08 due to water intrusion. I checked the connectors anyway. Sometimes the truck will just stall while idling in park. I feel heat has something to do with this but what???? Sure Track from Snap-on shows Techs have replace one ECM and One Camshaft Sensor, then a whole lot of Crank sensors. I have not seen anything that would suggest the Camshaft Sensor is faulty, nor the VVT sensors. They are all feed by the same V-Ref signal. Powers and Grounds check Ok. I have to be losing/missing something???
I have attached a picture of the Crank Sensor waveform when the truck is about to stall

Any thoughts/ideas would be greatly appreciated.


Greg

 

Have you checked pin tension / drag of the female pins in the connectors? A commonly overlooked problem, usually caused by ham-fisted probing when testing.

Disconnecting both ends of the harness and load testing with a 12V source and a sealed beam headlight would be on my list to do, while tugging and wiggling. I’ll admit I haven’t looked closely at mine, but does the harness to the CKP sensor run close to the exhaust manifold / downpipe? Check for baked wiring in that area if it is.

 

I'll give that a go.
Thanks for your reply!!