E53,How to read an Electrical diagram
 

Can anyone give me a basic education on how to read electrical (ladder?) diagrams. Having various electrical issues. What do all those numbers stand for. See alternator picture attached as example. Thanks.

https://www.yumpu.com/en/document/re...ley-publishers

I'm not an expert on reading wiring diagrams, but here is some info to get you started you can check out until someone with more experience can help.

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It would be easier to explain them on original BMW WDS (or NewTIS) diagrams. So what you actually need to know?

https://www.newtis.info/tisv2/a/en/e...ontrol/asmdexc

The link I sent is the company who makes bmw manuals but yeah go for it and ask a million questions

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the OP did ask for basic education, the link from @Boston01X5 looks like a perfect start point. It will be much easier for OP to ask an informed question when they learn a bit how to read the diagrams.

The labels starting with an X are connectors or junctions.

The labels starting with G are end devices (in the case of the diagram above). Other devices have other letters, e.g. the radio module is N9, the transmission module is A6000 etc.

The labels like "0.75" and "GN/WS" are the wire size and colour - 0.75mm, green/white in this example. Colours are in German, e.g. Grün = Green, Weiß (Weiss) = White etc.

I think the numbers like 15 and 30 refer to what ignition switch position (KL) the B+ voltage will appear on the labelled terminal, basically different voltage buses. There seems to be some variation to this though, as clearly the battery positive, label as 30 on the generator above, is present at all times! There are also similar numbers for earth buses etc.

*edit* just been reading that these voltage bus numbers are defined in a DIN standard... 30 is a direct battery connection, 31 is a direct ground, 50 is a B+ when the ignition is in the run or start position etc....

That's a very basic starter.... :thumbup:

On the wires: signal/voltage type, wire thickness (mm2) and wire colour like said in German.

On top of the supply or at the bottom:
Terminal 30: continuous battery voltage
Terminal R: switched voltage ignition pos. R
Terminal 15: switched voltage ignition pos. 2
Terminal 50: switched voltage ignition pos. starting
Terminal 31: direct ground

Thank you all for your help.
After 3 MAF replacements (1 New ) I keep getting a bad MAF which is why the electrical diagram as I suspect some wiring issue. As anyone knows there are at least 3 projects going on with these cars at any one time.
I attached a copy of the MAF diagram and am trying to muddle through it.

It's way more likely you have a bad MAF than a wiring issue.

It would be my 4th one if I buy.. within 4 months. One was OEM Bosch.