0340 code appears again after replacing cam syncro

[mctavish]

Hi everyone. I replaced my cam syncro and the sensor 3 months back after getting a P0340 code on my 2008 ranger 3.0L, auto, (400,000 KM). The old one still looked fine however. The check engine light went away and have not had any issues, until now. I have noticed a couple of times in the cold weather the battery strained for starting but I put in a new battery a year ago and have not had any alternator check lights on ,etc. I have read that the alternator could be sending spurious signals to give this code. Does this sound possible for a 2008? Other than the check engine light being on, it still runs fine. Any suggestions? Thank you.

 

[RonD]

If it wasn't a Ford sensor then sensor could be bad, 3rd party sensors do fail frequently, should still be under warranty.

You should have a Variable Reluctance sensor(2 wires) on an '08
Take a OHM meter and test the old sensor, should be over 200 and under 4,000 ohms, under 4k
And then test the one on there now.

There are 5 different CPS codes computer can use, 340 is Camshaft Position Sensor Circuit Malfunction
It could also chose "signal too low", "too high", "intermittent" or "out of range"
So 340 reads more like wiring issue not sensor itself, unless OHMs are out of range

These generate their own signal, so are not "powered", but I would test if the wires are shorted or grounded.
Key off
Test ohms from 1 wire to engine ground(metal), then the other wire.
Should not see 0 ohms on either, means wire is shorted to Ground.
Then test ohms between the 2 wires, not sure of that reading but shouldn't be 0 ohms, if it is the those 2 wires are shorted together.

CPS is there to fine tune fuel injection, engines ran fine for years without a Cam Position Sensor, it was added for better emissions and MPG, so best to have it working but having it not working won't noticeably effect engine performance, but this is also subject to computer software.

 

[mctavish]

Thanks RonD. I did use genuine motorcraft parts for this. I read also that the wire from the sensor going to the computer may be shared with some other things . I am going to get a wiring diagram and trace it out. I know this is probably not related but I did have my blinker malfunction a couple of times (goes fast) but is ok now. Maybe the diagrams will show some common ground somewhere. Thank you for your time.

 

[RonD]

Yes, the Grey/red stripe wire is common wire for most of the sensors, it ends up at pin 91 on computer

Dark Blue/orange wire goes directly to pin 85 on computer