Mountaineer

I have been getting a lot of good help on lots of topics here, I hope my luck holds out.

I have an L98 out of a 1987 Corvette. When I bought the motor lots of things were labled and tagged, but lots of stuff didnt get tagged or labeled. What I am working on now is the charging system. I have the charging wire harness which consists of these things:

1. + bat main cable that connects to + bat terminal and at the other end to the solenoid
2. a smaller red cable that is integrated with the main red cable at the bat connect terminal - this smaller red cable connects to and feeds 12V to a single terminal black plastic junction block
3. this junction block has wires that feed headlights, brake abs, etc
4. the junction block also has connected to it a single red cable (same size cable as 2. above) that connects to the bat terminal on the alternator.
5. the junction block has a smaller red wire connected - this wire is the "S" wire in the three wire connector that plugs into the alternator. The three wire connector plug has this "S" wire and also a blue "F" wire and a brown "L" wire. "P" on the connector is not used.

Now the problem and question...

The other two wires in the three wire connector that plugs into the alternator are the blue "F" wire and a brown "L" wire. ("P" on the connector is not used).

When I received the motor the blue "F" wire and the brown "L" wire were snipped off with no tag or label to say where they connect to.

Does anyone know where the blue "F" and the brown "L" wires connect to ? what do these wires feed, ? for example a volt meter / volts gauge ?

Ive tried also to find wire diagram for this but havent been able to locate one.

Well thats it, I would really appreciate any help on this one. Thanks.

87 vette 81 big girl

The Blue "F" wire is the Field connection wire.

Fed +12 volts from the ignition key with engine running.
Turns the alternator ON to start current & voltage output to operate all electrical systems & keep the vehicle battery charged.

The Brown "L - lamp" wire is connected to the dash indicator lamp/ DIC for the Red battery light (Idiot light).
Lights up when the alternator quits charging or the Key is on & engine off.

Brian

Mountaineer

THANKS , okay, I think I have it....

the "F" wire has to be hot with 12V when the motor is running, I can get this 12V from my after market ignition switch,this activates the alternator to beging charging.

The "L" wire, could this be used to feed an after market volt meter instead of the idiot light ? If not, how would you connect a volt meter in this system ?

87 vette 81 big girl

Yes.

L wire works best with Idiot lights though.

Voltmeter needs to connected to a Ignition key switched + 12 volt source with key on & engine running.

What are You building ?
A C4 Corvette or a streetrod, race car, or other custom project ?

Mountaineer

I glad you asked what Im building, I hope you think it is as cool as my son and I do... its an off road racer, the base frame, chassis and body are from a 1993 wrangler Jeep, although not much of the body is left. Chevy small blocks are hugely popular with the offroad crowd, and are "relatively" simple to put in a jeep frame. I am using a 700R4, which also fits pretty nice in the jeep chassis. So instead of just any Chevy small block, we wanted to be really COOL and put a Corvette motor in our racer, an early TPI due to the basic almost "never fail" reliability of the motor and relative simplicity of the MAF. Offroad we will dig the torque of the L98. Its a great project, and I dont think there are too many jeeps built for offroad racing that are running an L98 out of a 'Vette. My only Corvette, a '67 with a big block and factory side pipes, sadly had to go in a divorce many years ago, along with a 1966 Harley Davidson, talk about losing the good stuff....

Mountaineer

[QUOTE=87 vette 81 big girl;1578852184]Yes.

Voltmeter needs to connected to a Ignition key switched + 12 volt source with key on & engine running.

This gives me lots of options for a connection for the voltmeter -- easiest seems like it would be the "IGN" terminal on the after market (painless performance) ignition switch kit. That kit has a keyed ignition switch and six toggles that are energized by a single +12 small cable from the battery -- it s not cheap but its a really good solution to after market wiring when yoiu dont need all the bells and whistles in a stock vehicle.

87 vette 81 big girl

Sounds like a very fun father & son project your custom Jeep 4- wheel Corvette TPI machine.

I have used Painless Wiring Kits in the past.
Last 1 was in a friends 1957 Chevy Bel Air.
I had his car wired in 1 day & up & running.

The 1987 Corvette TPI with matching stock 700 R4 had only a 1,400 RPM stall at best.
If you install a custom hand built 2,000 to 2,200 RPM lockup torque converter they come alive.
Tire shredding power.
Make sure the MAF stays clean inside at all times too.
Dirt & dust buildup on the BOSCH Hotwire MAF Platinum filament causes erratic performance & immediate power loss.
Run a K & N large cone air Filter.
Use their supplied special Red air filter oil only, nothing else.

Want a C2 myself.
1965 - 1967.

Or a 1963 Split window would be very cool too.

Brian