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: Variable tumble control solenoid valve inspection
1. Remove the variable tumble control solenoid valve. (See INTAKE-AIR SYSTEM
REMOVAL/INSTALLATION.)
2. Inspect airflow between the ports under the following conditions.
If not as specified, replace the variable tumble control solenoid valve.
If as specified, carry out the Circuit Open/Short ...
Mazda 6 Service Manual: Abs (abs/tcs) hu/cm system inspection
System Inspection
Preparation
1. Verify that the battery is fully charged. With the ignition switch on,
verify that the ABS and BRAKE system warning lights goes out after 2.4
seconds.
2. If the lights stays on after 2.4 seconds, the ABS (ABS/TCS) HU/CM
detects a failure. Follow the troubles ...