Kevin Hodgkinson

I have 2005 GTO that's 5.3 swapped for boost but it has a low voltage problem And the dreaded alternator light. I've checked grounds, replaced batteries(4), replaced alternators(4), checked the BCM wires and bandaged them (no damage there), new battery posts and terminals, ran a 4 guage wire from the alternator to the battery, added a 4g ground to the chassis, replaced the pigtail connector to the alternator. I'm at a loss I can start the car and it runs fine for a few minutes within normal voltage range, but rev the motor or turn any accessory on. the voltage drops and shoots the check alternator light on the dash. At first I thought it was my alternator fans going because when I would unplug them the car would run without the issue. But the problem Soo resurfaced a couple minuets later. I'm starting to think it's the ECM or BCM because I have done everything from replacing parts ,checking continuity on wires, to looking for shorts with the mulitmeter following the guides. I'm lost please help!! Does anyone have any input? Mabe add an external regulator?

munciegoat

Is the Battery relocated? If so how is the wiring routed?

Kevin Hodgkinson

Jontall

Are you using the GTO alternator and ECM??? The GTO ECM controls the alternator and if you are using something different, it will not work.
https://www.dropbox.com/sh/bf4xvfch6...a/Uploads?dl=0

Kevin Hodgkinson

Jontall

Can you read the computer with a Tech2? Also, 2005/6 GTO does not have alternator fans.

Kevin Hodgkinson

Jontall

You need to buy one from China and you really need it to own a GTO or go somewhere (Autozone) that can read the codes.


Document ID# 1555695
2005 Pontiac GTO


Charge Indicator Always On



Step


Action


Value


Yes


No


Schematic Reference: Starting and Charging Schematics

Connector End View Reference: Engine Electrical Connector End Views


1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information


2

Start the engine.

Does the charge indicator remain illuminated?

--

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems


3
•Install a scan tool .
•With a scan tool, observe the Battery Voltage parameter in the instrument panel cluster (IPC) data list.

Does the voltage measure within the normal operating range?

10.5-17.5 V

Go to Step 4

Go to Charging System Test


4

With a scan tool, command the charge indicator lamp On and Off.

Does the charge indicator turn On and Off with each command?

--

Go to Step 5

Go to Step 6


5

Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 7


6

Inspect for poor connections at the harness connector of the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 8


7

Replace the engine control module (ECM). Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 9

--


8

Replace the IPC. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 9

--


9

Operate the system for which the symptom occurred.

Did you correct the condition?

Jontall

This will help you:

Kevin Hodgkinson

Jontall

The correct part number for the 2005-6 alternator is: ACDELCO 92211821

dreadpirateroberts

iTrader: (1)

The ECM monitors the voltage, can command the alternator on/off, and can control the duty cycle of the alternator. The gto uses an RVC type of alternator.

if you are searching on ls1gto and pulling up some of this stuff, i have to apologize. i probably posted some erroneous info while i was still figuring out how all this crap worked.

there are some documents on the internet, as well as some info in the factory service manual on how RVC alternators and the ECM interact. i can find them later if you want, i can't seem to find the appropriate thread on ls1gto right now.