Checking coil on 9 Turbo

Can anyone please tell me how to check the coil on a 1986 phase 1 turbo. I have a workshop manual but non of the info regarding the coil is correct for my model. There is no spark from tne HT lead when I disconnect it from the distributor cap and I need to check the coil. It has 3 connectors in a row.The first counting from the front of the car is a 3 pin connector but only the first 2 pins have connections labled "a" and "b". The midle connector has 2 wires not labled and the third connector has three wires again labed "a" "b" and "c". I have +12 volts on connector "a" and an earth on "b" of this third connector. There is also a single wire connected to the coil above these other connectors. Any idea how to test??? Thanks in advance!