There is a technical service bulletin out that may be your concern here. Here is a copy of it.
Some vehicles equipped with a V6 engine may exhibit a flickering condition of the headlamp, instrument cluster, radio, and interior lights during engine start-up and may continue during the first several minutes of engine idle. After several minutes, the flickering will subside but may not completely diminish. This may be caused by excessive electrical resistance in the battery voltage sensing circuit. Vehicle operation is not affected by this condition.
Reroute the battery sense line from the engine compartment power distribution box to the B+ terminal on the alternator. Refer to the following Service Procedure for details.
Here is the wiring schematic,I have circled the circuit in question