42 On the electrical diagrams, do the circuit numbers have any meaning?
Description
This article is from the VW Technical FAQ, by with numerous contributions by Jan Vandenbrande others.
42 On the electrical diagrams, do the circuit numbers have any meaning?
A: Yes. VW uses Bosch numbering scheme, as do BMW & M-B. The most common ones
are:
1 = Ground (0 Volt)
15= Switched Positive (Hot when ignition is on)
30= Always hot "12 Volt" (even though it'll closer to 13.4 Volt)
[From Jens, still needs to be verified]:
31 = Ground
30 = +12V (always hot)
15 = +12V (when ignition is on)
50 = starter
1 = ignition coil, low voltage
4 = ignition coil, high voltage
B+ = alternator main current
D+ = alternator exciter (load lamp is connected to this one)
DF = alternator input of regulator (not available from outside the alt.)
Not Bosch scheme, but ...
One important circuit for VW cars is X: it is basically the same as
15, but it is getting cold when 50 gets active, i.e. when you start
the engine. Ventilator, rear window heating and other circuits which
need a lot of current are connected to X instead of 15 to leave the
current to the starter when it needs it. You should connect your high
power amps/radios to X, also. Better no music for 5 secs. than pushing
your car in winter.
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