[Peter Serio]

I would pull the cluster & go thru the plug-in one more time, making sure that the right color wire is in the right cavity. Since this is a car that did not come with rally gauges the wiring needs to be re-positioned in the plug for the gauges to work.

GM has a color theme to their car & truck wiring so once you understand the wire insulation colors the wire itself tells you what circuit it pertains to.

Here is the list for a '68 to 71 Lemans or GTO with rally gauges (option). Note that one cavity in the plug is not used. So you have 11 wires total; in the plug-in.

The black plastic plug-in on the back of the main cluster is arranged so that each cavity is numbered. (1 thru 6 on the top & 7 thru 12 on the bottom.)

The plug-in is molded on purpose so that it will only fit into the gauge housing one way. (The two locking tabs on the sides on the plug-in are not the exact same width.)

#1 lime green (high-beam headlamps on indicator).

#2 Dark Blue with a white stripe (Right turn signal: green arrow).
#3 empty.

#4 Gray wire (dash lights, for night-time driving).

#5 Dark Brown ( Alternator charge "gen" light).

#6 Dark Green (Coolant temperature gauge).

#7 Tan (fuel gauge sender wire)

#8 Gray wire (dash lights, for night-time driving).

#9 Light Blue (Left turn signal: green arrow).

#10 Dark Blue (oil pressure gauge).

#11 Pink = This is your 12 volt + battery power feed to the gauge cluster from the Ignition switch- (key on).

#12 Tan wire with a black stripe (When grounded this turns on the "BRAKE" warning light in the speedometer circle).