1995 GMC Yukon Owner's Manual - Page 147

Charging System Warning Light I The red Charging System Warning light should come o n briefly when you turn on the ignition, before starting the engine, as a check to show you it is working. After the engine starts, the light should go out. If it stays o n or comes on while you are driving, you may have a problem with your charging system. I t could indicate a problem with the alternator drive belt, or s a n e other charging system problem. Have it checked right away. Driving while this light is on could drain your battery. If you must drive a short distance with this light on. it helps to turn off all your accessories. such a s the radio and air conditioner. Malfunction Indicator (Service Engine Soon) Lamp A computer monitors the operation of your fuel, ignition and emission control systems. This orange light should come on when the ignition is on but the engine is not running, as a check to show you it's working. If it does not come on at all, have it fixed right away. If it stays on, or comes on while you are driving. the computer is indicating that you have a problem. You should take your vehicle in for service soon. 2-75