Component Tests and General Diagnostics

1. Some twelve cylinder engines are equipped with a closed-loop cut out circuit which allows the engine to be in closed-loop feedback control only when the transmission is in gear. When the transmission is placed into "park" or "neutral", the engine will go into open loop and run richer, in most instances rich enough to fail the tail pipe emissions test.
2. Before attempting to test the emissions on a V12 model, look for an access panel on the passenger side of the trunk. Open the access panel and remove the jumper connection from the red connector, if equipped.
3. The vehicle will now stay in closed-loop in all cases during the emissions test.