P0339 Intermittent Crankshaft Sensor

Hello

First time on the forum,

2008 jeep liberty Sport 3.7L gas 63,000 km Mileage




My wife was driving down the highway when she said the jeep starting acting strange and died send a picture with red lighting bolt coming on. I got there and the jeep was definitely overheated on the gauge almost in the red. Couldn’t start it back up. Towed it to a mechanic who quickly looked at it and thought maybe it was the fan needed to be replaced and possible some problem with voltage from the fuse box wire connections dirty he said (his reason why it would not start), Suggested I remove at the connectors for the wiring on the fuse box and spray them down with electrical cleaner. At the time I could get the jeep started after a few tries and had to hold the gas and break petal at a any stops to get home. I cleaned all the wires and once disconnected they looked clean to me between the pins and harness


Since then I read the codes with a bluedriver and got the following:


P0335 Cranksaft sensor position A


P0691 Fan 1 Control Circuit Low


I replaced the crankshaft and camshaft sensor (read somewhere that one could be the other for the problem). Tried again to start the jeep and noticed the following strange things.


When I turn the key on the red lightening bolt shows up and takes about ½ minute to go away and the check engine light stays on until finally blinking (maybe that’s normal)


When I turn the key to start the engine if I let go normally it stops cranking but now it will continue to crank for about 10 second on its own unless I turn the key in the off position. It cranks but no RPM’s on the tack. And at the very end it seems like it almost wants to catch and sometimes get a little movement on the tack


Only error now I get now is P0339 Cranksaft sensor A Circuit Intermittent.




I tested the crankshaft plug before the sensor and get the following:


5 volts across pin 3 (4.9 to 5.1 changes a little)

Ground is good back to the negative terminal on the battery (connectivity test)

Pin 1 to the number 35 pin on the PCM harness is good (connectivity test) tried wiggling to make sure

I have a fully charged battery 12.6 volts




If I unplug the crankshaft sensor I can actually get the jeep to start and run by holding the pedal down??


I am wondering if it’s the PCM (ECM not sure which term is correct) hate to order one on ebay that comes programmed if you give them your model and VIN and find out that’s not the problem. Not sure what else to check, possible the cranksaft senor from NAPA was a dud?? ….Any help would be great