This is the text of a post i made about a Rover Mini.
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Thanks for the start,
I have got to the bottom of this, and I will post the steps.
1 Finds the plugs for all the units.
2 Disconnect the battery.
3 Pull off the plugs to the pre-tenshioners, and control unit.
4 Take the steering cowl off and find the connection on the fixed part of the rotator unit, and pull that plug.
You now have a dead system, and you can start to rebuild it, but you need some resistors to simulate the nodes.
5 Buy some 2.7 Ohm resistors from Maplins and put them into the the plugs.
The system is now set to simulate all the air bag and pre-tenshioners.
6 Spray the plug and socket to the control unit and plug it in, then connect the battery and switch on the ignition.
The warning light now works correctly, switch off and disconnect the battery
7 Add the pre-tenshioners one at a time spray cleaning each plug and socket, but switch off and disconnect the battery each time, WAIT 10 MIN AFTER DISCONNECT BEFORE MAKING A NEW CONNECTION.
8 Remove the air bag and re-make the connection at the fixed part of the rotator, move the resistor to the air bag plug at the moving part of the rotator.
9 This last test proves the rotating connection, if all is still working put back the air bag.
I my case the system had no faulty units, just bad connections.
I did not need to touch any unit with a test meter.
Jon the Chief
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The post I did had pictures but that web site was more picture friendly