See also:

Onboard Diagnostic System — OBD II
Your vehicle is equipped with a sophisticated onboard diagnostic system called OBD II. This system monitors the performance of the emissions, engine, and automatic transmission control systems. ...

Loose Fuel Filler Cap Message
If the vehicle diagnostic system determines that the fuel filler cap is loose, improperly installed, or damaged, a gASCAP” message will display in the odometer or a “CHECK GASCAP” message ...

Quadra-Trac I Operating Instructions/Precautions – If Equipped
The Quadra-Trac I is a single-speed (HI range only) transfer case, which provides convenient full-time fourwheel drive. No driver interaction is required. The Brake Traction Control (BTC) System ...