To our knowledge, there have been at least four different ALDL connectors
used world wide (and probably more exist too!). Tell us
about them!
In Australia, the VN and VP models used a 6 pin connector. The
diagnostic link, a paper clip (red dotted line), is used to enable "flashing
diagnostic mode", and is not described here. The data from this connector is at
160 baud when the diagnostic link is a 10k ohm resistor. You'll find this
connector under the glove box on the VN/VP.
Connectors
6 Pin Australian connector
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Here's a view of the 12 pin US style ALDL connector, and where to connect the above circuit to. The pin numbering scheme is the same as that used on the VN/VP Holden Commodores (but those vehicles used the 6 pin connector shown above). This diagram is courtesy Carsten Meyer.
Later Australian Commodore models (VR, VS, etc.) use a 16 pin OBD-II style connector, but the pinouts are unique to Australia. This connector is located under the steering wheel.
European Opels use a 10 pin connector. Image courtesy Bert de Boer of Holland.