KLCC almost always means the mall/Petronas Twin Towers and not the city centre.

Jln Pinang is off Jalan Ampang. Heading to KLCC should not be a problem. It's the most easily recognisable building in Malaysia and there are plenty of signages pointing to it as you drive in KL (more so when you get onto Jln Ampang)

I recommend parking inside KLCC itself (remember to note the floor/section where you park and as you enter KLCC, which exit/lift you used. It will save u a lot of time/trouble when it's time to leave) esp. if you are buying lots of stuff from PC Fair.