Vehicles have various electrical parts. To protect the parts from excessive current generated when welding, be sure to perform the following procedure.
1. Turn the ignition switch to the LOCK position.
2. Disconnect the battery cables.

3. Securely connect the welding machine to the ground near the welding area.
4. Cover the peripheral parts of the welding area to protect them from weld spatter.

Electrical troubleshooting tools
Jacking positions ,vehicle lift (2 supports),safety stands (rigid rack)
positionsMazda 6 Service Manual: Power window motor inspection
Drivers Side
1. Disconnect the power window motor connector.
2. Apply battery positive voltage to the power window motor terminals E and F
and inspect the operation the power window motor operation.
If not as specified, replace the power window motor.
3. Apply battery positive voltage ...
Mazda 6 Service Manual: Power window main switch inspection
Drivers side
1. Remove the driver-side front door trim.
2. Connect the power window main switch connector.
3. Measure the voltage at the power window main switch terminals as indicated
below.
4. Disconnect the power window main switch connector before inspecting for
continuity at terminals 1 ...