Let's narrow down what you should be looking at. You have an ABS/Traction Control light and the throttle issue. I would focus on those first as they are likely related. The C121C code is the reason why you are having those issues. That is flagging an issue in which the traction control system is limiting the torque or throttle input provided by the ECM. Basically when the traction control systems kick on part of that is limiting the amount of throttle or power going to the tires. The other part of traction control is activating the brakes on the spinning tire to slow it down and shift power to the other side wheel with traction. If the traction control was somehow activating that would give you the dead pedal. For the gear issue, it could limit overall power preventing the upshift or even be dragging a wheel which causes more resistance and thus not being able to pull a higher gear. Or again could just be limiting throttle input so it doesn't have enough power to pull the higher gear.
Point being.....focus the effort on the ABS/traction control systems and the C121C code.
For the other reported issues:
- If there is an issue with the ABS/traction control and the light comes on, that typically disables cruise control. There is likely no issue with the cruise control, just that it is being disabled because of the ABS/traction control issues. Once you fix the ABS and traction control the cruise will probably work fine again.
- P0344 is for an intermittent camshaft position signal. First, that is unlikely causing any of your main problems listed above. Based on that I wouldn't even worry about it yet until you have the other problems fixed. The camshaft position has absolutely zero to do with the ABS or traction control. The code also does not say the only possible cause is that the sensor itself is bad. From my experience at least half of the time it's a bad wiring, connector, etc.... I do not recommend randomly throwing a new sensor on it because of the code. Typical cheapo parts store sensors also regularly have issues or simply don't work quite right. I typically recommend original Mopar sensors.
- P0456 - typical evap emissions codes, like a loose gas cap.....has abosolutely zero to do with your issues. May not even be an active code
- P0481 - cooling fan 2 circuit. Again, unlikely to have anything to do with the main issues listed at the start of this post. Unless the engine was actually overheating it won't cause issues, and obviously has zero to do with ABS or traction control. Again may not even be an active code...just because the code is shown in the system it doesn't mean that issue is active. If something happens just long enough to set the code, but then goes away, the code remains stored in the system for a period of time.
