The actual code is a 1690. Which is crankshaft position sensor code, but it doen't have a crankshaft sensor. So it really makes no sense to me. I figured it just meant the camshaft sensor, so I replaced it. How do you get the keyway in backwards? Looks like it only goes in one way to me. I've installed them before without any problems. Just put the key way at 12 Oclock and pull the old one. Set the new one at 12 and gentle slide it in.
JT,
Now we're getting somewhere!
That P1690 DTC actually refers to a problem with the fuel sync circuit between the ECM and VP44 computer and not a missing camshaft and/or crankshaft angle sensor fault. There are different DTC's for those. The engine behavior you've described fits in nicely with DTC P1690.
There are four general causes for this DTC:
1. Excessive interference (noise) on the power being supplied to the ECM.
2. A problem with the wiring harness between the ECM and VP44 (an open or short).
3. The static timing on the VP44 is incorrect.
4. The ECM has an internal problem.
In order of probability, I'd hazard a guess the wiring harness would be most suspect. Here's how you check it:
Disconnect the 9-pin VP44 connector and the 50-pin ECM connector. Using an Ohmmeter, check for continuity between pin 18 of the ECM connector and pin 8 of the VP44 connector (diagrams attached). The wire you're checking is 18 Ga and Dark Green. The resistance between the pins should be less than 5 Ohms. If greater, you have an open circuit and you'll need to find and fix the break in the wire.
Next, check for continuity between each of these same pins and a good ground. Any continuity at either pin with the ground indicates the wire is shorted somewhere and you'll have to find and fix the cause.
If nothing turns up in the wiring harness, then I'd next suspect the static timing of the VP44 might be off. But you can safely dismiss this possibility if you're *sure* the VP44 drive gear wasn't moved off a tooth one way or the other (highly doubtful because I'm not sure that's possible without removing the timing gear cover) and you're *sure* you used the correct key and it's orientated correctly (see arrow on attached diagram).
As to noise on the power supply...
According to the Dodge diagnostic manual, noise which affects the VP44 fuel sync circuit originates from the lift pump circuit. While that's a possible source of the problem, I'd think it'd be doubtful since the truck has a FASS system. I think the only way to check for noise properly would be with an oscilloscope. If noise is found, Dodge recommends replacing the lift pump.
Failing the above, the only thing left is the ECM being at fault.
Please keep us posted on what you find.
Good luck,
John L.