Printable Version of Topic

Click here to view this topic in its original format

914World.com _ 914World Garage _ Electrical Schemtaic Education Needed

Posted by: kenshapiro2002 Oct 2 2009, 07:02 AM

So, for example, when looking at the tachometer on the schematic, the three bottom wires are numbered 31, 15 and 1 and are not circled. those same wires all have the number 20 at the far end and those 20s are circled. I have no idea what any of that means.

The red #30 coming off the fresh air fan relay has a damn circled 11 right in the middle of the line before it gets back to fuse #12.

TIA for the education.

Posted by: SLITS Oct 2 2009, 07:17 AM

Well, let's see

Generally .... 1 is ground, 15 is hot and 31 would be the wire from the "sending unit". These are the connections on the back of the tach.

The circled numbers are traces. The first page shows the wire running from a device, but is terminated on the schematic with a number circled. On the second page of the electrical schematic there should be an equal circled number which indicates where the first wire continues.

I believe this to be the truth.

Posted by: Spoke Oct 2 2009, 07:22 AM

31 is ground. Pin 31 is consistently used on other elements as ground. For the tach, pin 31 goes off page on reference 22. Reference 22 is connected to ground point B.

15 goes off page on reference 21 . Reference 21 connects to fuse 9. This is 12V power for the tach.

1 goes off page on reference 23. Reference 23 connects to the engine relay board on cabin harness pin 7. Pin 7 connects to engine harness pin 5 which connects to the ignition coil on the NEG terminal.

So in general, 31 is the ground for the lamps, 15 is 12v power for the tach, and 1 is the signal from the coil to drive the tach.

Did I pass the audition?

Posted by: SLITS Oct 2 2009, 07:35 AM

I guess I should have been looking at a schematic ... apparently got the numbers all mixed up. Rats .............

Posted by: Spoke Oct 2 2009, 07:40 AM

QUOTE(SLITS @ Oct 2 2009, 09:35 AM)

I guess I should have been looking at a schematic ... apparently got the numbers all mixed up. Rats .............

I had pin 15 mixed up until I looked at your response so I guess I cheated on the test. I had to go back and edit my response. Even the simplest things take teamwork.

Posted by: ghuff Oct 2 2009, 11:05 AM

Some of the 914 are current flow diagrams as well Ken.

It helps to think of the terminal #'s as a "bus" or trunk.

Pelican parts has a better explanation of current flow diagrams than I could give.

http://www.pelicanparts.com/914/914_electrical_diagrams.htm

QUOTE(Pelican Parts)

How do you read a current flow diagram? It took me a little time to figure it out. Look at it this way. Imagine that you are looking at a diagram that shows waterfalls emptying into a lake. At the bottom of the page (electrical ground), it is similar to a large lake that the waterfalls empty into. At the top of the page (high voltage potential) it is similar to the top of the cliff, right before the waterfalls off the edge. Each path that the current diagram shows can be interpreted as a separate waterfall that turns a small turbine and generator as it falls down into the lake. The electrical accessory can be seen as the generator. The battery of the car is similar to a pump that pumps water from the lake back up to the cliff.
After you get used to them, you will undoubtedly find that the current flow diagrams are much easier to read, primarily because they separate circuits from each other. You don't need to mess with one circuit that you don't care about, just to find an electrical fault in another. The current flow diagram can tell you everything that you need to know right away.

Posted by: ghuff Oct 2 2009, 11:07 AM

If I remember right, 31 ground, 15 = switched hot key start position, 30 = key on hot, and 1= constant hot no matter where the key is....

The "terminals" revolve aroung the switching logic built into the ignition switch.

Kind of standard german/euro thing.

I may be wrong, and probably am but it helps to think of htem this way because the terminals go beyond the circuit you are dealing with.