4.3 MPI Alternator Wiring

J_C_E

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Hello im doing a v-belt-> serpentine swap/upgrade and bought a new MPI alternator. It has a black connector with RED and YELLOW wire. I Assume other is ignition/15 and other is Voltage sensing/adjusting. Witch is witch ?

Can the igniton/15 be routed through a bulb in the dash ? I have a voltage gauge but would like a bulb also. :rolleyes:
 

Don S

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Re: 4.3 MPI Alternator Wiring

Got a serial number? Been different alternators on the MPI engines over the years.
 

J_C_E

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Re: 4.3 MPI Alternator Wiring

Got a serial number? Been different alternators on the MPI engines over the years.

Part nr is 862031T1 . Dont have engine serial since its a custom built by me.
 

Don S

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Re: 4.3 MPI Alternator Wiring

Serial number of the engine, not a part number.
 

Don S

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Re: 4.3 MPI Alternator Wiring

Better yet, a picture of the back of your new alternator.
 

Don S

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Re: 4.3 MPI Alternator Wiring

The yellow wire will connect to the purple wire (Excite circuit), the red will go to the red/purple stripe wire (Sensing circuit).
 

J_C_E

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Re: 4.3 MPI Alternator Wiring

The yellow wire will connect to the purple wire (Excite circuit), the red will go to the red/purple stripe wire (Sensing circuit).
Ok, Thanks Don! Can the yellow be routed through a charging lamp/bulb ? Like usually the D+ is routed through a charging lamp/bulb.
 

Don S

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Re: 4.3 MPI Alternator Wiring

The purple is also the ignition circuit, power to everything from the switch. You could probably route it like that, but the light would be on any time the ignition switch was in the run position.
 

J_C_E

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Re: 4.3 MPI Alternator Wiring

The purple is also the ignition circuit, power to everything from the switch. You could probably route it like that, but the light would be on any time the ignition switch was in the run position.
Yes same as in cars, and goes off when engine is running and alternator is charging/working.
 

Don S

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Re: 4.3 MPI Alternator Wiring

Yes same as in cars, and goes off when engine is running and alternator is charging/working.

No stays on as long as the ignition switch is in the run position. If the light goes off, the engine dies. No ignition.
 

J_C_E

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Re: 4.3 MPI Alternator Wiring

No stays on as long as the ignition switch is in the run position. If the light goes off, the engine dies. No ignition.

I ment routing a separate wire to the alternators yellow wire through a lamp. Ignition switch->lamp->alternator yellow wire. I have a custom made wiring harness in my boat and engine. So the wiring is not original mercruiser wiring.
 
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