OBD-II Troubleshooting

[Toyguy]

Wondering if anyone has any thoughts on troubleshooting the following issue.

My new Durametrics tool works fine on the DME and Alarm modules but cannot seem to talk to anything else in the car. From what I have gathered from research and from Durametrics support, the likely issue is a fault on the K2 line somewhere.

I know that K2 is on Pin 3 of the OBD connector, with Ground on pins 4 and 5. Is there any way to tell if pin 3 is active? Can I meter it for a voltage or something like that?

I have the Bentley Service Manual but I have to go buy a magnifier to make out the wiring diagrams :-) A quick glance through though didn't show a specific page for the OBD circuit but it may be on some of the other pages.

Any advice greatly appreciated.