This is from memory - I try to avoid having to pull an instrument cluster.

Most wires connected to the cluster will fit only one way, but there are some that are otherwise.

Tach connections should be a single wire R/W with insulated female connector. that is the signal from the coil, and if connected to something else there is a possibility of fried elecronics. The other tach connection is a 3-wire harness to the small clock. It provides to the clock its ground(SB), its constant power(R) and its lamp power(GN)which is part of the dash/control panel lighting.

There is an orange lead for the cruise control. Looking from the back side of the cluster, it goes on to either of the two male spades at the upper left of the speedo.

There may bo others, I don't remember. Last time I was in there was to install a Volvo Cruise Control system.

Over the time I have owned Volvos I have obtained for each car the Volvo Service Manual Wiring Diagrams manual, including the one for the 1987-88 240s. Not a low-cost manual, but contains info unavailable elsewhere. 1-800-25-VOLVO and ask if it still available.

Good Luck,

Bob

:>)