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: Pid/data monitor inspection
1. Connect the WDS or equivalent to the DLC-2.
2. Measure the PID value.
Note
Perform part inspection for the output device after PCM
inspection.
The PID/DATA MONITOR function monitors the calculated value of the
input/output signals in the PCM. Therefore, if a monitored value ...
Mazda 6 Service Manual: Cooling system service warnings
COOLING SYSTEM SERVICE WARNINGS
Warning
Never remove the radiator cap or loosen the radiator drain plug
while the engine is running, or when the engine and radiator are hot.
Scalding coolant and steam may shoot out and cause serious injury. It may
also damage the engine and cooling sys ...