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volvo 240 exciter wiring

When the alternator "self-charges" it outputs voltage on the exciter terminal as well.
It's used as a safeguard to make sure that only the switched voltage is affecting the circuit.
 
JohnLane said:
*Ding! You nailed it.
Click to expand...

Darn, I read up on 1990 Audi's Bosch Alternator (110-amp), and wonder what ohm spec is for earlier 70 amp Volvo/Bosch alternator (1977-1985).

RESISTANCE CHECKING

Disconnect negative battery cable. Disconnect Blue wire
terminal of alternator. Connect Multimeter (US 1119) between Blue wire
and battery positive. Turn ignition on. If readings is not 140-160
ohms, replace instrument cluster printed circuit and recheck.

I like that instruction, just replace that instrument cluster printed circuit...piece of cake right?:omg:


Footnote - Discussion on VW Forumn - Alternator Exciter Wire, 12v needed to charge?

PS: Another Discussion - 100 amp alternator, exciter wire doesnt function as normal
 
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I'm slowly building a new cluster for my 940 and this alternator circuit is the one stumbling block. I want to replace all my warning lights (or most of them) with LEDs. After spending many hours on the net I found some information and decided to build something to accomplish the same function of the alternator exciter circuit. It requires 1 diode, 1 resistor, and LED and a circuit board. Here is the finished product:

2012-11-28_17-57-43_533.jpg


Haven't tested it yet but will in the next few weeks and I'll report back.
 
Natural244 said:
alternator exciter circuit. It requires 1 diode, 1 resistor, and LED and a circuit board.
Click to expand...

I cited this in above post, which explains a method:

"2 resistors, one diode and one lamp. 1K in series with the led. 270 ohm 2w in parrallel with the led & resistor, 4004 (4A) in series with it all

The 220 limits the current to start the field, its a sink at that time. Once current strats to flow from the alt, it becomes a source and the led stops glowing."


Discussion on VW Forumn - Alternator Exciter Wire, 12v needed to charge?
 
Unless you are building race car why mess with what works and works well? When the instrument cluster is bypassed with the substitute charge light. The other lights won't get tested on initial key on. So you lose a bit more functionality as well.
 
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