95 Merc 454 Alternator/Voltage Issue

[cmcguire]

Having a voltage issue with this 454. I have a brand new marine alternator. It is the 5 wire - two exciter wires pigtails and three wire bolt on.

The voltage gauge is pulling a negative voltage on revving the motor. The motor will not stay running when disconnecting the battery.

Can I get a schematic of the wiring of this alternator (more specifically wire colors and which studs they attach to) for this?

Or, is it something else? It reads 12 volts before starting. When at idle it reads 12 volts - I think it should be closer to 13-14 volts when idleing and maybe close to 14.5 at higher rpm's...It draws down to around 9-10 volts when revving the motor.

I am using a good hot, new optimum gel battery.

Any ideas?

Thanks.

Chuck

 

[Bt Doctur]

Re: 95 Merc 454 Alternator/Voltage Issue

Never seen a 5 wire
GM Single wire Orange and Black
GM 3 wire Orange, Black , Red, purple(black)
NEVER disconnect a battery to check the charging system WITH AN ALTERNATOR

 

[JustJason]

Re: 95 Merc 454 Alternator/Voltage Issue

Yep... if it's more than 3 wires then something is wrong, or your year of the engine/alternator/charging system is incorrect and you have an old fashion seperate alternator/regulator rectifier.

 

[Juniinc]

Re: 95 Merc 454 Alternator/Voltage Issue

perhaps its the 4 wire altornator.
two exciter wires pigtailed from B+?

 

[cmcguire]

Re: 95 Merc 454 Alternator/Voltage Issue

My alternator has two excite wires red and purple with bullet terminals that plug into the wire harness with bullet connectors and the color of the wire matches. I know I have those wired correctly.

Now I also have 3 other wires that go onto the alternator.

NOTE: I also have a black wire that comes out of the harness, but have no idea where this wire could go on the alternator...?!? If you count the black, I have 4 wires plus the two exciter wires(purple and red).

2 of the wires bolt on, the third wire has a push on terminal that pushes onto one of the studs on the back of the alternator.

There are more studs than there are wires.

Any access to Schematics?

Thanks.

Chuck

 

[cmcguire]

Re: 95 Merc 454 Alternator/Voltage Issue

This is what my alternator looks like.

http://www.boatfix.com/eshop/53023.jpg

There is 4 studs. Two at the bottom, and two under those nylon nut covers.

Where does which wire go?

 

[Bondo]

Re: 95 Merc 454 Alternator/Voltage Issue

Any access to Schematics?

Ayuh,... There's factory manuals in the Aduts Only section at the top of this forum...

 

[Don S]

Re: 95 Merc 454 Alternator/Voltage Issue

This is from Service Manual #16, item #2 in the drawing is the automatic choke coil.

 

[ghostgixxer]

Re: 95 Merc 454 Alternator/Voltage Issue

My alternator has two excite wires red and purple with bullet terminals that plug into the wire harness with bullet connectors and the color of the wire matches. I know I have those wired correctly.

Now I also have 3 other wires that go onto the alternator.

NOTE: I also have a black wire that comes out of the harness, but have no idea where this wire could go on the alternator...?!? If you count the black, I have 4 wires plus the two exciter wires(purple and red).

2 of the wires bolt on, the third wire has a push on terminal that pushes onto one of the studs on the back of the alternator.

There are more studs than there are wires.

Any access to Schematics?

Thanks.

Chuck

I know it’s an old thread! I also got issues figuring out the wiring .. especially the 2 lil wires you said "connected & the main wiring harness " those wires has been cutter short and heat discoloured them !! Any idea what colour they were ?

 

[Bt Doctur]

just hook them up . if reversed the motor will not shut off.

 

[achris]

Guys, 10 year old thread. Read the forum rules, start a new thread of your own.

Chris............
iboats mod team.