No Voltage from alternator so I am looking for the wiring schematic to troubleshoot the wireing circuit

What is year--make--model? I can't look up wiring for your charging system w/o more info?
Do you have voltage at alternator bat terminal, key off? If nothing there, may be problem with wiring circuit or fusible link to battery. Also, most alternators need excite voltage or they won't work. If problem with wiring circuit to or from alternator, replacing the alternator won't fix it.
Some makes and models may have trouble codes for charging system, any applicable trouble codes?

It looks like you are off to a good start in finding the problem with your Opel's no-start condition. You next step should be looking at an overall map (schematic) of the vehicle's power system.

You see, the signal from the alternator to the injectors is grounding out somewhere, probably along the body. Tracing the path from the alternator to your Opel's injectors is not difficult, but it is time-consuming and requires patience because it does require some painstaking work, if you choose to do it yourself. You will need a reasonably good volt-ohhmeter, plus the schematic that you already have. Before you start your trace, identify the locations of the test points that you need. I would suggest that you look closely at Opel's website to find any conventions that they may use in identifying test points. The test points to look for are in the ignition circuit. I actually think that you have a problem with the signal from the alternator to the spark plugs going to ground somewhere so that it never reaches the top of the spark plug body. So, you will need to find the spark plug circuit and then look for the voltage, going from test point to test point.

If, as I suspect, the problem is in the electrical system, specifically the firing circuit for the spark plugs, then there will be a point where the voltage disappears. That is where your problem is.

This procedure is complicated by the fact that the wires you need to find, the ones carrying the voltage you are looking for, will likely be buried in a loom. A loom is a large bundle of wires surrounded by either ties or an outer sheaf of insulating material. You will have to separate the pair of wires you need from the loom which is not an insignificant task.

Troubleshoot by isolating the alternator, then testing for a 13.5 - 16v output (likely to be ~14.5v). Anything out of that range indicates bad alternator or voltage regulator (assumed to be built into the alternator). If voltage is in range, (and following your suspicion of an electrical problem in the Turn Signal circuit), reconnect the alternator and isolate the turn signal circuit by pull the fuses. See if you are getting the good voltage reading of (~14.5v) at the battery. IF IT'S GOOD..check for bad trailing wiring harness (isolate if possible), I've seen bad turn signal bulbs (contacts on bottom of bulb) short out (melt) in their sockets (typically causing a blown fuse..but ya'never know), and lastly you might have to do a hand over hand following the wiring, looking for shorts, melted wire, cuts, broken connections, etc (see Hanes Manual Wiring diagrams for possible points to perform continuity checks). IF IT'S BAD. you must continue to isolate electrical circuits until you find the one that is causing the fault. You can pull one fuse at a time (not reinstalling them) until voltage at the battery returns, or you might try pulling a group of fuses at a time until you can read good voltage at the battery, then replace the fuses one at a time until you find the bad circuit. Once you've isolated the bad circuit, it's either a matter of further isolation until you find the bad component (many circuits supply voltage to multiple components), or checking every connection and component connected in the circuit. Best of luck resolving this problem.

First off, disconnecting athe battery while the engine is running is the quickest way to damage an alternator. Unlike the old DC generators, the alternator needs the battery in circuit to protect it against voltage runaway.

If the alternator has been bench-tested and seems to be functional, I would start by verifying the related vehicle circuits. Witch a DC voltmeter, start out by measuring the voltage at the alternator's output terminal, the heavy black/orange wire. It should be full battery voltage. If it is anything less than battery voltage, you must determine why. Some things to look at are the gray 12-gauge fusible links A & B, and the various splices and connections in the circuit (see diagram below).

Next, disconnect the voltage regultor harness plug from the alternator and check the voltage at the wiring harness regulator plug's "A" terminal connector - the yellow/white wire. It too should be full battery voltage. If it is anything less than full battery voltage, you must determine why. In this case, look at the 20-amp ALT fuse in the battery junction box, and at the various splices and connectors in that circuit.

Then, turn the key switch to its "RUN" position and measure the voltage
at the wiring harness regulator plug's "I" terminal connector - the light green/red wire. It should be somewhere between 8 and 12 volts. If there is no voltage present, check Fuse 5 (15 amps) in the main fuse panel and the various connections in that circuit.

The final test is to measure the voltage between the batterty positive terminal and the alternator housing or frame. If it is anything less than full battery voltage, check the alternator mounting.

knowing the color codes can be a great help..usually in 12v reg system,from the regulator there are 6 white wire having a stripe codes,blue means neutral,green means field,black means ground to body,white means hot wired to +12v,yellow means to bat charging indicator going to instrument panel and finally red means to ignition....and always secure the regulators case to ground.

Check all your wires that go to the starter and alternator, back to the battery. Something is not right in that circuit. You will probably need a wiring schematic to check properly. If you need anything else, please let me know. I am here to help.

The pcm contains the voltage regualtor,have you checked the charging voltage?If it is overcharging most likely is bad pcm.

The voltage regulator is inside the alternator.The normal charge voltage is 13.8 to 14.2 volts dc. There is a fusible link that goes to the feedback wire on ford alternators to tell it to turn on.If the link blows open,the alternator will not charge,and replacing the alternator will not solve the problem.The schematic shows clearly that part of the circuit.

1. Check the voltage on the White/Red wire at the 2-pin connector on the alternator. Key on engine off there should be near zero volts and when the engine is running and the alternator is charging the voltage should the charging system voltage (13.8 - 14.2 volts). Voltage drop the alternator case to battery negative. Voltage drop the battery positive circuit to the Black/Red wire (Large wire on output post) and the Yellow/Black wire in the 2-pin connector (sensing voltage). Looking for 0.05 volts maximum.

2. Disconnect the 2-pin connector at the alternator when the engine is running and the alternator light is on. The light should go out. If not, then there is a circuit problem (shorted to ground).

voltage sensing circuit could have a problem, if the sensor is bad that senses the voltage coming from the alternator or battery it will set this warning off, follow the wires from the battery and alternator untill you find what looks like a little module or a clamp around either the negative or positive battery wire or alternator wire. see if the vehicle reacts when the module or sensor is moved around a bit