Chassis earth wire to battery melting plastic cover

[Fu Manchu]

This is how and what you need to sort it. An osciloscope.

Without it you are not going see the voltage fluctuations.

These guys are in Dandenong.

Yes yours in not a VE but it’s the exact same process.

 

[Fu Manchu]

Test the wiring integrity.

Is there continuity between the pin for that coil at the ECU and the coil?

Do it with the ECU unplugged. Negative terminal disconnected at the battery first. Then unplug.

Don’t push probes into plugs though. You’ll splay the terminals and create poor contact and one hell of a head ache to sort as you chase gremlins caused by the splayed terminals.

Best to use a pin or needle connected to the multimeter. Jaycar might have a back probe set.