348 Wiring Diagrams

this may help
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Their may be variations from car to car. e.g. plug 115 on the upper left side of the engine bay may be rectangular on newer cars (with different pin numbering). This circular plug is fragile and known to cause issues.

I see the diagram only shows one wire (yellow/green) going to the small connector of the alternator. Doesn’t the 348 alternator have a typical 3-pin plug?

 

A bit more work for you Ian. I happen to have a new engine harness on which I did some wire tracing.

The pinout of the 3-pin socket on the alternator is (looking at the socket):
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The wiring diagram only shows the Y/GN wire that goes from "L" to the alternator warning light (via Pin 6 of the 9-pin connector). The other two pins are:

IGN: GN/W wire - goes to Pin 5 of the 9-pin connector which provides +12V ign. supply (shares it with the Speedo Sensor)
S: R wire - short wire for volt Sensing, has an eye terminal that connects to the alternator's power output stud

 

The updated pinout of the 9-pin connector:
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Thanks Miro...

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Full size download here:

https://www.dropbox.com/t/NuU74JROEIPPAeil

Link expires in 6 days.

I've added some late model 348 plug detail on the right of the diagram

 

No battery/alternator warning light? I had a broken pin on my alternator connector (I can't remember which of the 3 wires it was, but my battery voltage was dropping and the light was coming on).

Before you go pulling your alternator, I would check the continuity of the wires between plug 115 and the alternator. Also the red wire.

 

Do the checks as suggested by Ian first. Otherwise, the symptoms you described could also mean that one alternator phase is out due to blown diode(s). In such cases, the voltage is fine with light loads but drops at heavier. Another possibility is partial shorts in the rotor (exciter) coil. Have a look at the attached document and the alternator testing procedures.

 

Have you determined which kind of connector you have near the left hand rear suspension strut? Circular or rectangular?

I don't have a photo of the circular plug (other than m.stojanovic's improved version)

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The rectangular type is something like this:

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Ian, a couple of suggestions for your revised diagram for Starter and Alternator:
1. The symbol "L" at the connections to the alternator is at the wire which is actually to "IGN" pin; you can leave the "L" where it is, just swap the two green wires.
2. The pins listing (1-12) appears to apply only to the rectangular connector; perhaps you can insert a note to that effect (the round connector pinout is as shown on my drawing posted above).

 

Thanks, Miro
I've squeezed both pinouts into the one diagram
I couldn't really swap the wires on the alternator as the original diagram has the green/white wire specifically going to the bottom of some kind of internal resistor. I've labelled all the wires now.

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Full-sized diagram here:

https://www.dropbox.com/t/EFRKliMpmTs4mL76

Cheers

 

Great. Just a small final touch: the vertical runs of the two green wires to the left of the alternator - if you place the "1.5 VB" closer to the alternator, and the 1.5 GV further away, you will avoid the two green wires crossing each other twice.

Cheers

 

I sometimes use the double-cross technique to put extra space between objects. With multiple lines, it makes the diagram look less cluttered (and not much harder to read).

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Anyway, here's an optional version

https://www.dropbox.com/t/t2rP0xPiPnP5Gr8y

I'm not sure of the wire gauges for the alternator. In the original diagram, the GV wire increases in size as it gets closer to the alternator. Anyway, on my (F355) alternator, all the wires on the small plug are the same size, so I've done the same for the 348. i.e. 1.5 mm^2.

 

Thanks, I like the "optional" version. As to the sizes of the 3 wires to the alternator, GV and VB are same size (2.4 mm dia. over the insulation) so they are 1.5. The red wire is a bit thicker (3 mm) so it should be "2" I guess.

 

Sorry to hear there is nothing obvious.

By the way, what sort of earth do you have on your alternator? Some folks have an additional earth wire on the alternator due to the inadequacy of the standard earth. I don't know if all cars suffered from this shortcoming or just the early models.

 

Is one wire (red) of the three wires in the 3-way plug connected to the main B+ stud? You can see the mentioned red wire on this picture (by Ernie):

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Adding a ground strap to the alternator may not solve the problem but it is good to have one just in case the grounding via the lower bracket develops some resistance.

 

On the F355, the red wire goes to the equivalent of new plug 115. I think it's the red/black wire on pin 10. Perhaps Leigh can confirm this?