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Bosch Alternator Wiring 240z


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#1 sexual_sushi

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Posted 17 June 2012 - 01:47 AM

Hi guys, I bought a Bosch alternator from Supercheap (BXD1242a) a few years ago but never fitted it. Now I've come to chuck it in my 73 240z and the wiring is a little different.

There are the obvious earth points and the BAT or B+ terminals but the old alternator had a 'T' shaped terminal with 2 connectors, L(amp) & S(ense). The new alternator only has one terminal called D+. I think I can disregard the S connection (leave it unconnected) and then hook up the L connection to the new D+, can anyone confirm?

Originally the car had an external alternator, I replaced this with an internally regulated unit using the plug with a diode in it (http://www.thezstore...ZS/PROD/12-4068).

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Notes taken from http://www.zhome.com...ech/280Alt.html
1. An "L" connection which goes to a "switched" 12V supply. By this I mean a 12V source that is active only when the ignition switch is in the ON position. I use the mnemonic "L" for "lamp", the alternator warning lamp (if used) is in series with this connection. This terminal also supplies the "excitation" current to the alternator field winding at engine turn on, allowing the alternator to begin producing voltage as the engine is ramping up to idle speed. Once the alternator rotor is turning fast enough, it generates it's own supply for the field winding and the current in the "L" connection stops flowing. The warning lamp (if used) goes out.

2. An "S" connection which goes as close to the positive terminal of the battery as physically possible. The "S" connection "senses" the battery voltage and this is the voltage that the regulator is tying to control. This connection has a high impedance, so it only draws only micro amps from the battery, so it can be left connected without fear of battery discharging.


                        "S"
                    ...............
                    :  -------  :
                    :....  |  ....:
                        :  |  :
                        :  |  : "L"
                        :.....:




#2 Six_Shooter

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Posted 17 June 2012 - 03:32 AM

I'm not familiar with that particular alternator, but if you look at a diagram fro the vehicle it was originally fitted to, or for, you can see what circuit is used to trigger it to turn on, find the same circuit in the Datsun wiring and connected together.

I know when I did my Bosch alternator swap, I used the harness from the external regulator to make a jumper for the batt sense and ignition wires. So the wire you need should be in that harness.

#3 RB30X

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Posted 17 June 2012 - 09:45 AM

This didn't help.


#4 dazzed

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Posted 17 June 2012 - 03:42 PM

the bosch alternator already has a inbuilt regulator so an additional external regulator is not required, so this wiring diagram dont suit this alternator and no charge light in 240z which you need

#5 matty260z

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Posted 17 June 2012 - 06:10 PM

B+ is just battery and D+ is warning light. So just connect your earth, battery onto B+, and the (L) plugs onto D+ disregard the sense wire, done.... You don't need an external regulator as that bosch until is internally regulated.

#6 sexual_sushi

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Posted 18 June 2012 - 01:26 PM

Haha I'm now slightly less confident than when I started.

However I will try hooking up the 'L' to the D+ and disregarding the sense wire and see how I go as this seems the easiest to do at the moment.

Cheers

#7 dazzed

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Posted 19 June 2012 - 01:46 AM

B+ is just battery and D+ is warning light. So just connect your earth, battery onto B+, and the (L) plugs onto D+ disregard the sense wire, done.... You don't need an external regulator as that bosch until is internally regulated.

quote must have missinterperted or what ever i wrote was, wont comment again

#8 sexual_sushi

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Posted 19 June 2012 - 10:19 AM

quote must have missinterperted or what ever i wrote was, wont comment again


??

#9 Scoota G

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Posted 19 June 2012 - 01:47 PM

I think I can disregard the S connection (leave it unconnected) and then hook up the L connection to the new D+, can anyone confirm?

I have a Bosch Alternator, the White wire with Black stripe is hooked up to D+ with a diode.

#10 sexual_sushi

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Posted 07 July 2012 - 12:09 AM

So I have the L connection hooked up to the D and everything seems to be working fine. I accidentally had the S hooked up originally and I can confirm that this does not work, it would discharge the battery over night.

Thanks for the replies guys :)




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