So, how does one test the sub-componants in a HID system?

The car I am currently looking at is a Volvo V70.

Neither light works.

The Bulb is fitted into a ballast that sits where the bulb would normally go in a conventional headlight.

There is a three terminal connector leading to this.

What voltages (trace) should I be getting on these three wires?

I suspect that I am going to have to replace the ballasts anyway because the contacts are partially burned away. But it would be nice to do a proper diagnostic rather than just throw parts at the car until it is fixed.

Hi Paul, do you mean for aftermarket fit HID or OEM?
James

Very difficult to test Hid systems.It is possible to check input power to the main ballast unit,usually located below the headlight,but output to the bulb is around 20kv strike voltage.Works a bit like a coil ignition system.Easy way is to swap parts from the other side headlight,but with 2 in trouble,that makes things more difficult.On some cars ,there are more gubbins inside the headlight that are not reachable or replaceable as individual parts.