Intercooler connectors

[ykphil]

I just replaced the glow plugs for the first time on my 1995. Easy job, although I didn't notice any noticeable improvement at starting. However, I noticed when I removed the intercooler that one of the orange/white electrical connector had been left disconnected and taped by the previous owner. The black connector was connected. I reconnected the orange/white connection, but do not see any difference from when it was not connected. What is this connection about, and what should it do? Should I keep it disconnected? TIA