I have a 2004 Deville DTS that wont turn over. When the key is inserted and turned on, all the appropriate lights on the instrument cluster come on. All window and door locks work. Radio and AC/fan all work. Turn signals, head lamps,all work. When I turn the key to engage starter, instrument cluster goes dark and I hear a few clicks from the relays under the back seat. Checked battery and meter reads 11.7 volts. Any thoughts as to the cause or advice on how to proceed, would be appreciated.

Joe