alternator and starter wiring

[stranger45]

Can anyone tell me what wires coming off the firewall go to the alternator and what wires go to the starter?

[MT-2500]

Originally Posted by stranger45

Can anyone tell me what wires coming off the firewall go to the alternator and what wires go to the starter?

You are going to Have to give up year make and model and truck sise and engine and trans and 2-4 W.

Large 12 volts pos wire/cabels run from battery to starter and alt.
Most of other small wires run into wiring harness from alt and some from starter.

What is your problem?
Or why are you wanting to know about wiring or what happened to them?
Missing or not hookd up?
For help.
Please explain?

[stranger45]

It is a 1985 K20 3/4 ton, automatic transmission with a 350 engine, wires are not hooked up.

[MT-2500]

Originally Posted by stranger45

It is a 1985 K20 3/4 ton, automatic transmission with a 350 engine, wires are not hooked up.

Is the engine harness to alt and starter still there?
Does it have battery cable pos to starter?
Is the alt to battery feed wire pos there?

[MT-2500]

On starter smalle purple wire goes to start terminal on solenoid.
The large pos. battery cable and battery feed wire to truck goes on large solenoid terminal.

On alt I show a larger 12 volt post wire from battery pos to large terminal on alt.
And another smaller battery pos wire to alt voltage regulator.
And a brown wire from dash to alt regulator.
If there is two small wires in a alt plug in just plug it into alt.
If not tell us what wires you have there?

[stranger45]

yes engine harness to alt and starter are there, yes battery pos to starter
battery feed wire positive to alt is not there

[MT-2500]

Originally Posted by stranger45

yes engine harness to alt and starter are there, yes battery pos to starter
battery feed wire positive to alt is not there

THEN RUN A HEAVEY GAUGE WIRE FROM ALT LARGE POST TO BATTERY POSITIVE.
BIG ENOUGHT TO CARRY ALTERNATOR OUTPUT OF 100 AMPS OR MORE.
Aso make sure one of the small wires to alt has 12 battery positive on it.
Let us know how it goes.

[MT-2500]

On a lot of them them year the alt pos to battery runns from alt to firewall junction block.
If you run a new wire from alt to battery positive to battery or firewall junction block make sure the old origional wire is not hanging or laying around some place where it can short out.
Are you installing a motor or alt and starter or how did you come up with a missing alt. pos. wire?
Let us know where you are at and how it is going.
Very good idea to make sure the alt. pos wire to battery does not short out any place.