WHERE is the hole to pass wires thur the firewall of a Chevy Express van?

In a Chevy Express van, the most common location to pass wires through the firewall is on the driver's side, near the brake booster. Look for a rubber grommet or an existing wiring harness that can be used to feed wires through. If necessary, you can create a new path by carefully drilling a hole, but ensure it’s properly sealed afterwards to prevent moisture intrusion. Always check the vehicle's manual for specific details related to your model year.