Error code p2101 involves the electronic throttle control. Which essential controls your throttle, the car won't accelerate if the code went away and came back after you changed the battery chances are it's just the throttle control sensor which isn't that expensive to replace.
What size engine ? The clicking you hear is probably the starter relay , provided you hear the click while turning the key to the start position . That black box is the fuse / relay junction box. Testing the starter electrical circuits with a volt meter is the way to find the problem . Voltage drop testing . Free wiring diagrams here http://www.bbbind.com/free_tsb.html Enter vehicle info. Year , make , model and engine size . Under system click on engine then under subsystem click on starting . Click the search button then the blue link.Does your vehicle have a manual or automatic transmission ? First blue link for a manual transmission ,the second link for a automatic transmission .
How to voltage drop test starter motor circuitVEHICLE RELAYS Operation Diagnosis
YES you need them, ENG MTG is the Engine Management system, and the ENG CONT is the
Engine Control system so you see if they are disconnected you will have a good time wondering what is up with the car
If you have done all the usual tune up stuff, check to see if holding the gas down a little helps. If so, could be a dirty/sticking idle air control valve. Other possibility is bad coolant temp sensor telling the ECU engine is warm when it is not.
Most parts stores will have a loan-a-tool pressure gauge. Your shop manual will have the pressure spec. Don't have a manual? You should buy one for lots of usful info.
The door switch isn't making a ground necessary to make the bulb work. If it's just one door, look at replacing the door switch. If none of the doors will work the light, then look at the body control module.
Most auto supply stores ( NAPA ) will carry a socket that is designed to remove wheel locks. You may have to bang the socket on with a hammer and sometimes the nuts are hard to remove from the socket once taken off the car, but it works
Look at the front of you A/C compressor with your A/C sent to max. the front of it should be moving with the rest of the pulley, if not you most likely have a leak and it's out of freon. If it's moving and still no cool are careful touch the pipes coming from the compressor, one is you hi side and the other low side. The smaller one (hi) should be warm or hot... the other (low) should be cold and sweating. If the clutch on the compressor is moving and those lines aren't hot and cold then your low on freon.
