Positive Ground Disconnect in Trunk

[Mowgli81]

My first of many questions to come should be a simple one. In the trunk is what appears to be a "ground" disconnect. There is a small 12ga wire that also runs from this into a wiring harness. Testing the unit it appears that when it disconnects the positive terminal it then connects this small wire to the chassis?

Now the question: What is it for and is this operating correctly?

Thanks I feel kinda silly asking sorry.

 

[TimK]

This is not a silly question! Welcome to the best Healey forum (IMO)
The small wire (white with black stripe) should run to the coil in the engine compartment. It grounds the coil so the ignition won't function (anti-theft) when the main ground is disconnected by the switch.

 

[Mowgli81]

Thanks so it should connect the chassis to this small wire. That makes sense now. Thank you I'm sure I'll be back! I love the internet.

 

[John Turney]

The thin white with black wire should not be connected to the chassis, it should be connected to the switch or to nothing. Otherwise, your car won't start because the coil is grounded out.

 

[TimK]

The wire is connected to the chassis through the master battery switch when it is turned to off. It grounds the coil when in this position so the ignition cannot function. This is an issue of semantics. You are correct when the master switch is on. It will not be grounded when the master switch is on.