Alternator wiring

[Ron B.C]

I had my alternator checked and turns out it is good. Its a 1 wire Bosch unit. AL8659. The 1 wire on the plug (red with black stripe )that runs into the harness that should go to the ignition or some ignition switched power if I am correct. I am having trouble locating where that connection is. I dont see any red/black stripe wire under the dash/fuse panel etc.

Edit: there is 12v running to the alternator on the 1 wire plug from ignition source. But no volts coming out on the b+

[Jyrocharlie]

Battery +

[twinboat]

Is there 12 volts at the ( bug ) output wire going to the alternator ?

[Ron B.C]

Originally Posted by twinboat

Is there 12 volts at the ( bug ) output wire going to the alternator ?

There are 2 wires on the alternator. The small 1 that goes into the rectangular plug from ignition source has 12v. The larger output wire that runs to the battery shows 1 to 3 v

[Jyrocharlie]

A picture of the back of it would help, and , what it's supposed to fit. The guys that tested it likely know what that wire goes to when it checked ok.

[Ron B.C]

[ATTACH][/ATTACH]

The small wire is on the second pin. "I"

88 Chev 454

I had it back to the shop, they tested it a second time with me standing there.
Everything checked out on it.

[twinboat]

The battey wire should have 12 volts on it.

Follow that bigger wire and find out if it goes to the battery or to an isolator.

Your picture shows 2 different alternators, confusing. Did you replace the Delco with the Bosch ?

The shop tested it and its fine, but it doesn't work ?

If you have a isolator in the system, you may need to use the exact Delco you took off.

I see two small wires on the plugin connector. One is ignition, is the other one hot all of the time ?

[Ron B.C]

Originally Posted by twinboat

The battey wire should have 12 volts on it.

Follow that bigger wire and find out if it goes to the battery or to an isolator.

Your picture shows 2 different alternators, confusing. Did you replace the Delco with the Bosch ?

The shop tested it and its fine, but it doesn't work ?

If you have a isolator in the system, you may need to use the exact Delco you took off.

I see two small wires on the plugin connector. One is ignition, is the other one hot all of the time ?

The 2 pictures are of the same alternator and there is only 1 wire in that plug.

[twinboat]

How did they test it, on the engine ?

Does the batt wire go to a isolator ?

[cfowler55]

Looks like it is a Delco alternator that has been rebuilt by Bosch. The large wire is battery positive. You should have 12 volts all the time on that wire. Should be a fusible link wire close to the battery. Pull on it , if it stretches the wire is burned thru inside the insulation. Also make sure it has not had an isolator added inline somewhere.
Charlie

[theoldwizard]

Originally Posted by cfowler55

Looks like it is a Delco alternator that has been rebuilt by Bosch. The large wire is battery positive. You should have 12 volts all the time on that wire.

Closer to 14V when the engine is running at high idle !

[Ron B.C]

This 1 is above the alternator. It is for the starter as I jumped it and the motor turned over. Im not sure where the small red wire with the yellow end goes. There is no voltage on it but it is on the live side of the solenoid.

This 1 is under the hood, Left side comes from the battery and then runs to the starter motor. right side has 1 large gauge and 2 smaller gauge wires. I coudnt get any voltage to the right side with key on or jumping the solenoid, so i would say its cooked and will replace. There was no voltage to the small terminal with key on either. I bypassed the solenoid and put power to all the wires on the right side then checked for voltage at the alternator and still had nothing. I didnt see any fusible link from the alternator to the battery. but there is some spots of the harness I could not see.

[Ron B.C]

Is there any reason why I shouldnt run a new cable from the alternator to the battery? Bypass any isolator I may be missing.

[twinboat]

That can be done, or as most factory installs, run the wire from the alternator to the battery post on the starter motor.