For quick reference, here are the vital statistics for your 2003 model: 3.4L V6 (LA1)
Flush and replace cooling system (DEX-COOL). 4. Common Troubleshooting "Quick Fixes"
If an electronic component stops working, check these two locations: Chevrolet Venture 2003 Manual
GM often provides archived manuals for older models in PDF format.
If the automatic door fails, check the "On/Off" switch on the overhead console. Often, cleaning the brass contact pins on the door frame with rubbing alcohol restores the connection. For quick reference, here are the vital statistics
Inspect engine air filter and replace if dirty.
These third-party databases host free PDF versions of the 2003 Venture Owner's Manual. For quick reference
Replace spark plugs and inspect fuel system.