[woodmanscott@hotmail]

First i would like to say that i am saddened by doc's passing i only knew him here in the forums but he has helped me alot .. i have not been online so i am just seeing the post as of now ......



i am having problems with my alternator when i crank up the truck it takes a second for the alternator to kick in while you are waiting if you rev the engine the voltage goes up and down with the rpm but once it kicks in it hod 14 volts when i said it takes a second to kick in i meant more like 30 any ideas

[66GMC]

What kind of alternator?

Two possibilities come to mind ...
1.) Some alternators require a voltage "signal" to excite them ... so perhaps a loose or corroded connector or wiring?
2.) Worn brushes ... and the springs can't push them far enough into the slip ring.

Yeah ... we all miss the Doc.

[woodmanscott@hotmail]

i believe it is a delco-remy and it is atleast 7 yrs old

[68NovaSS]

If it's a one-wire alternator, as 66GMC says, they require 12-1500 rpms to activate the charge, after that they charge at idle and act like an externally regulated alternator.

[woodmanscott@hotmail]

it has 3 wires going to alternator 4 if you count the main battery wire..it is on a 2000 gmc sonoma 4.3 v6 i read online where it says that he trucks computer controls the charging and if there was a trouble code when the alternator failed that it would have to be cleared before it would charge.. but i have checked the codes and a local shop and there are no codes not even any stored that pertain to the charging system when the alternator is charging it does great ... but i was just wondering if the lagging whne you first crank it means that the alternator is going out or if the computer is going out ?

[66GMC]

According to the WAI Catalog that truck should be using a Delco-Remy CS-130-D series alternator, that should look like this:



According to the "Bill of Materials", this is the
Votage Regulator ... which is where your 4-wire plug goes in.
Perhaps someone else will jump in here and explain what the "P-L-F-S" terminal technology means. (P = PCM, L = Light, F = Field, S = Stator?)

They also mention that this regulator is designed for a digital dash.

Based on what you were told about the alternator needing a "signal" from the PCM ... and what I believe those terminal ID's to be ... I would assume that a specified voltage (12V?) applied to the "P" terminal would "excite" the alternator.

Can anyone confirm or deny that?

It might be safest to either take it to a shop and have them diagnose it, or to remove that alternator from the vehicle and have it "bench-tested".

[woodmanscott@hotmail]

thanks for all the help i will take it and have it bench tested under load and see if it works correctly or not and let you know what i find