Hi Jim,

Thanks for the email. The way I read it is as follows;

The instructions are asking you to check the primary and secondary resistances of the coil.

The reason it is asking you to connect a THREE volt battery into the circuit is to switch on the End-stage inside the coil.

This is because the End-stage has control of the primary circuit and without turning the End-stage on the circuit would not be complete and not testable via a resistance test.

A far quicker and more reliable way of testing the primary resistance would be to use an Amps clamp.

This was the sort of circuit detail that I was talking about in my first post. How can you test something without knowing how it works?

If this is the setup on Pete's vehicle then there was no need to send the ECU away at all.

The Enable signal from the ECU can be tested with a scope. With the rest of the circuit being tested via volt drop testing or an amps clamp.

Regards Mark