1. Check the Obvious:
* Power: Is the power sliding door switch illuminated when activated? If not, there's a power issue. Check the fuse (consult your owner's manual for the correct fuse location and rating for the power sliding door). Also, check the main power connections to the motor.
* Child Safety Locks: Ensure the child safety locks on both the interior and exterior of the door are disengaged.
* Door Obstruction: Something might be blocking the door's path. Manually try to open and close the door to see if it's physically obstructed. Look carefully at the tracks for debris, ice (if applicable), or anything that could jam the mechanism. Clean the tracks thoroughly.
* Switch Functionality: Try both the interior and exterior switches. If one works and the other doesn't, the problem is likely with the faulty switch.
* Remote: If you have a remote keyless entry, try using the remote to operate the door.
2. More Advanced Troubleshooting (Requires some mechanical aptitude):
* Motor: The most common cause is a failed motor. You'll need to access the motor (usually located within the door panel) to check for power at the motor itself. A multimeter will be necessary to check voltage. If no power is reaching the motor, the problem lies elsewhere in the wiring. If there's power but the motor doesn't run, the motor is likely faulty and needs replacement.
* Wiring Harness: Inspect the wiring harness connected to the motor and the switches for any damage, loose connections, or broken wires. Pay close attention to the areas where the wires bend and flex as the door moves. A visual inspection might reveal a frayed wire.
* Control Module: The power sliding door is controlled by a module (possibly integrated into a larger body control module). A faulty module would require professional diagnosis with a scan tool. This is less likely to be the problem unless other electrical systems are also malfunctioning.
* Limit Switches: The door has limit switches that tell the motor when to stop. If a limit switch is faulty, the door might not open or close completely, or it might act erratically. These are usually difficult to access and test without significant disassembly.
3. Repair or Replacement:
* Switch Replacement: If a switch is faulty, replacing it is relatively straightforward. You can find replacement switches online or at auto parts stores.
* Motor Replacement: Replacing the motor is more involved and might require some mechanical skills. You'll need to remove the door panel to access the motor. New motors are available online and at auto parts stores. This often requires specialized tools.
* Wiring Repair: Repairing damaged wiring requires careful soldering and insulation. If you're not comfortable with electrical work, it's best to seek professional help.
* Module Replacement (Least Likely): Replacing the control module is generally a job for a qualified mechanic.
Important Notes:
* Consult a Repair Manual: A repair manual specific to your 1999 Chevy Venture will be invaluable. It will provide detailed diagrams and instructions for accessing components and troubleshooting the system.
* Safety First: Always disconnect the battery's negative terminal before working on the electrical system.
* Professional Help: If you're not comfortable working on your vehicle's electrical system, it's best to take it to a qualified mechanic. Diagnosing electrical problems can be challenging, and improper repairs can lead to further damage.
By following these steps systematically, you should be able to narrow down the cause of the problem and make the necessary repairs. Remember to prioritize safety and seek professional help if needed.
