Did u do the exhaust instal yourself? I did my exhaust work on my 300zx and forgot to plug in the harnesses on the passenger side, in to much of a rush
and had a problem. Pretty embarrassing because it took a while for me to figure out. I was with out my z for at least 2-3 days I was pissed. Has to wait till I had time to look into it and it ended up being a 2 min fix.
Or if you dropped one when u switched then all over, it might break....GL though keep us updated on the findings.