On my home forum, some one posted this proposed POS test procedure. I didn't like it because of the 12V that he applied (I think the ECU only applies 5V to the POS) and the fact that he could have figured out the mis-matched Cylinder 4 and 5 POS connections by examining the wiring. Here is the procedure (what do you think?):
"Hi Guys/Gals,
I was able to finally get my S6 firing on all 5 cylinders again but it was quite a witch hunt. So I've had some questions on how I did this, and decided to post the logic here.
Well the positive side of the coils are permanent, which are the white plugs.
The negative side of the coil is triggered, and the computer provides the trigger pulse in the form of a positive pulse at around 5V.
You WILL need a LED-test light to do these tests. Connect the negative terminal of the test light to ground, and undo the plugs going into the bottom of the POS units (both of them) then you will need another person. Get the other person to turn the engine over, and look for the light pulse on the LED light as you go along all of the connections in the PLUG side, i.e. coming from the ECU. There is a ground in each of the plugs, and then the others (three in one plug, two in the other) should give a pulse each time the engine turns over. Check that you have pulses on 5 wires... Remember which connections those pulses are, this is important. The POS units reverse this small positive pulse into a negative trigger pulse for the coils, so for the next test you need to reverse the connections to the LED. So to test the POS units, reconnect the bottom connectors on to the POS units, make sure you have a test point (best is a pin) to the negative side of the LED tester, and connect the positive of the LED tester to the positive post located nearby under the plastic cap. Then with the negative side of the tester, go along each of the output pins on the top (output) of the POS unit. You should get a light pulse once per revolution of the engine. Of course one of the outputs on the top of the POS unit that only has two connectors, will be dead and this is the 'spare' channel. Finally check that the coils are connected to the channels that have pulses, the connections go straight through the POS units so if the right wire is missing on the input, then the right connector on the top should be dead. Make sure that the right wire on the coil connector side is also missing, this is where mine was messed up, someone had used the spare channel previously but I exchanged the whole engine side of the ignition which resulted in the mismatch.
Hope this saves someone some time, the test LED should be bright otherwise it helps to do this at 11PM at night... Thanks specifically to UrS4boy for providing some of the essential circuit diagrams and help me through this. You're welcome to add this section into your troubleshooting section, whihc was most useful but assumes factory-correct connections..."
"Hi Guys/Gals,
I was able to finally get my S6 firing on all 5 cylinders again but it was quite a witch hunt. So I've had some questions on how I did this, and decided to post the logic here.
Well the positive side of the coils are permanent, which are the white plugs.
The negative side of the coil is triggered, and the computer provides the trigger pulse in the form of a positive pulse at around 5V.
You WILL need a LED-test light to do these tests. Connect the negative terminal of the test light to ground, and undo the plugs going into the bottom of the POS units (both of them) then you will need another person. Get the other person to turn the engine over, and look for the light pulse on the LED light as you go along all of the connections in the PLUG side, i.e. coming from the ECU. There is a ground in each of the plugs, and then the others (three in one plug, two in the other) should give a pulse each time the engine turns over. Check that you have pulses on 5 wires... Remember which connections those pulses are, this is important. The POS units reverse this small positive pulse into a negative trigger pulse for the coils, so for the next test you need to reverse the connections to the LED. So to test the POS units, reconnect the bottom connectors on to the POS units, make sure you have a test point (best is a pin) to the negative side of the LED tester, and connect the positive of the LED tester to the positive post located nearby under the plastic cap. Then with the negative side of the tester, go along each of the output pins on the top (output) of the POS unit. You should get a light pulse once per revolution of the engine. Of course one of the outputs on the top of the POS unit that only has two connectors, will be dead and this is the 'spare' channel. Finally check that the coils are connected to the channels that have pulses, the connections go straight through the POS units so if the right wire is missing on the input, then the right connector on the top should be dead. Make sure that the right wire on the coil connector side is also missing, this is where mine was messed up, someone had used the spare channel previously but I exchanged the whole engine side of the ignition which resulted in the mismatch.
Hope this saves someone some time, the test LED should be bright otherwise it helps to do this at 11PM at night... Thanks specifically to UrS4boy for providing some of the essential circuit diagrams and help me through this. You're welcome to add this section into your troubleshooting section, whihc was most useful but assumes factory-correct connections..."