So recently my 850 wagon has been on the fritz, the first issue i ran into was the positive battery terminal overheating, i believe this to be the cause of my car not reliably starting seeing as all the other portions of the ignition system are good. In addition to this my abs and srs warning lights come and go occasionally while driving which worries me but hasn't led to anything catastrophic just yet. Lastly driving home last night going roughly 40-50 mph my transmission dropped into third gear for maybe three seconds, it proceeded to do this spontaneously a few more times on that trip. This morning trying to rearrange cars. i had to use the shiftlock overrride to get out of park rather than just depressing the brake. The battery indicator light came on this morning as well so i suspect that is part of my many problems but any help right now is good help.

 

problem 1: battery terminal heating up is caused by resistance from a bad connection. You need to clean the terminal and check to make sure there's no corrosion inside the wires (or consider replacing the terminal/cable). This can cause a voltage drop and odd electrical behavior or weak starts.

problem 2: transmission oddly shifting gears. I'd check three things - a) make sure the transmission fluid level is correct and not blackened b) try to clean up the PNP sensor (shifter position sensor) by doing a "shifter row" (engine off, key unlocked, go from Park to Lo to Park 20x fast). This may be enough to clean the contacts. c) fix the battery cable right away. Drops in system voltage while driving can confuse the transmission computer and sensors. The ABS and SRS warnings may have been caused by the same voltage drop - but you can also have the car scanned for any stored codes.

 

Yep, start with the battery and go from there. Also, make sure your battery is fully charged.

 

What mt6127 said...fix that battery terminal FIRST