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: Engine coolant temperature (ect) sensor inspection
Note
Perform the following inspection only when directed.
ECT Sensor Resistance Inspection
1. Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS.)
2. Remove the ECT sensor (located above the starter).
3. Place the ECT sensor in water with a thermometer, and heat the water
gra ...
Mazda 6 Service Manual: No.5 tcs off light does not illuminate with ignition switch on
Diagnostic procedure
When performing an asterisked (*) troubleshooting inspection, shake the
wiring harness and connectors while doing the inspection to discover whether
poor contact points are the cause of any intermittent malfunction. If there
is a problem, check to make sure co ...