Hello, i have a 2002 European Neon 2.0 SOHC with 4-speed automatic trans.
Since a few days i am having ODB fault codes P1684 and P1698. They came with intermitent abnormal behaviour: speedometer does not move at all; transmission in emergency mode (only 2nd gear), vibrations in the engine more than usually, today also noticed that the fuel gauge is slowly oscilating a few (between two consecutive marks). But sometimes, I start the car and it runs completely normaly.
The first think i have done is to clean the battery terminals but the problem persists. I have tested with a multimeter the battery voltage and it is normal. With engine on, the voltage is around 14V so the alternator seems to be working (might it be failingin intermittently?)
It seems to me some electrical / electronical issue, any advice about what to check?
P1684: car battery was disconnected within the last 50 starts.
P1698: means the PCM is not recieving a bus message from the TCM.

 

This issue was caused by a damaged TCM, it resulted filled by water from the heavy rains, the insulating gel from inside was deteriored. Replacing the TCM fixed this issue.