Your description of key turned on and key turned off is too vague. Lets call ON where the key is in the engine running position. Call START where the key is turned all the way to the right and you are trying run the starter to crank the engine.
According to this wire diagram you should have 3 wires connected to the starter and the starter will need to be grounded. 1 wire is connected to the battery at all times, labeled circuit 30 in the diagram below and is the large stud coming out of the starter solenoid. The other two are the two smaller studs coming out of the solenoid. They go to the starter solenoid and ignition sytem as follows.
With the ignition on there should be no current coming out of the starter solenoid at pin 87 in the diagram. Pin 87 should go to a fairly large violet wire and will go to one of the smaller terminals at the starter. That terminal is labeled 50 in the diagram below and may be labeled 50 on the starter as well, or it could be labeled "S" or possibly something else in the German language meaning start, or it may not be labeled at all.
A smaller, looks like a red and violet wire on the starter goes to the ignition system to by pass one of the ignition system ballast resisters during start up. In the diagram below it looks like that one is labeled 16 on the bottom of the starter and may be labeled 16 on the starter or "I" or in German accordingly.
Check that you have 12V at the large stud on the starter at all times.
Check that you have 12V on the other two terminals with the key in the start position.
Check that the 2 smaller terminals are on the correct post.
![Product Schematic Font Circuit component Parallel]()
According to this wire diagram you should have 3 wires connected to the starter and the starter will need to be grounded. 1 wire is connected to the battery at all times, labeled circuit 30 in the diagram below and is the large stud coming out of the starter solenoid. The other two are the two smaller studs coming out of the solenoid. They go to the starter solenoid and ignition sytem as follows.
With the ignition on there should be no current coming out of the starter solenoid at pin 87 in the diagram. Pin 87 should go to a fairly large violet wire and will go to one of the smaller terminals at the starter. That terminal is labeled 50 in the diagram below and may be labeled 50 on the starter as well, or it could be labeled "S" or possibly something else in the German language meaning start, or it may not be labeled at all.
A smaller, looks like a red and violet wire on the starter goes to the ignition system to by pass one of the ignition system ballast resisters during start up. In the diagram below it looks like that one is labeled 16 on the bottom of the starter and may be labeled 16 on the starter or "I" or in German accordingly.
Check that you have 12V at the large stud on the starter at all times.
Check that you have 12V on the other two terminals with the key in the start position.
Check that the 2 smaller terminals are on the correct post.
