Fox T-Bird/Cougar Forums

Technical => Electrical Tech => Topic started by: CarbonDioxide on September 30, 2018, 02:05:16 AM

Title: AMP Light on dash 3.8 V6
Post by: CarbonDioxide on September 30, 2018, 02:05:16 AM
So just purchased a 1987 T-Bird with the 3.8l. Put a new alternator in it, pushing 14 volts to the battery while running, but the amp light warning is on in the dash. Anybody got any ideas what it could be?
Title: AMP Light on dash 3.8 V6
Post by: softtouch on September 30, 2018, 02:36:56 PM
The S (Stator) output from the Alternator to the S (Switch) input on the Voltage Regulator is supposed to Switch Off the warning light. The White/Black stripe wire.
The Stator output should be about ½ the Alt output, 7-8 volts.
Do you still have the stock 2G alternator?
Title: AMP Light on dash 3.8 V6
Post by: CarbonDioxide on September 30, 2018, 03:05:00 PM
The guy I got the car from had the alternator put on, how can I tell between 2g and 3g
Title: AMP Light on dash 3.8 V6
Post by: softtouch on September 30, 2018, 03:50:24 PM
Quote from: CarbonDioxide;467346
The guy I got the car from had the alternator put on, how can I tell between 2g and 3g

The 2G out put is a 3 wire connector. 2 BK/O wires are the B+ output and the W/BK stator wire.
The 3G has a single wire ring connector with a nut on it for the B+ output. The stator output is a separate connector.
Title: AMP Light on dash 3.8 V6
Post by: CarbonDioxide on September 30, 2018, 05:25:08 PM
Appears to be the stock 2g.
Title: AMP Light on dash 3.8 V6
Post by: softtouch on September 30, 2018, 05:32:20 PM
Can you post a pic of what you have?
Title: AMP Light on dash 3.8 V6
Post by: softtouch on September 30, 2018, 06:14:04 PM
Usually those new/rebuilt 2G's come with a new output connector with "pig tail" wires attached.
This is so you can cut off your old connector and splice the wires to the new connector.
These connectors have a history of overheating and being damaged.
Title: AMP Light on dash 3.8 V6
Post by: CarbonDioxide on October 01, 2018, 01:25:24 PM
Yeah, I'll snap a picture here in a couple hours. Sorry for the late replies.
Title: AMP Light on dash 3.8 V6
Post by: softtouch on October 04, 2018, 04:52:33 PM
Maybe this will help:
Title: AMP Light on dash 3.8 V6
Post by: softtouch on October 04, 2018, 05:33:22 PM
Are you sure you have an 87 T-bird?
If it is an 86, the 3.8L V6 could have a 1G alternator. This alternator has an external regulator. Not one that is part of the alternator.
Title: AMP Light on dash 3.8 V6
Post by: CarbonDioxide on November 01, 2018, 05:27:37 PM
I'm sure I have an 87 with the original 2g. Still no resolve
Title: AMP Light on dash 3.8 V6
Post by: softtouch on November 03, 2018, 01:52:01 PM
Did you check for stator voltage on the  W/BK wire?
Title: AMP Light on dash 3.8 V6
Post by: softtouch on November 06, 2018, 05:29:03 PM
[COLOR="#FF0000"]Disconnect the negative battery cable[/COLOR][COLOR="#FFF0F5"][/COLOR] before doing the following connector checks(there are HOT wires in both connectors)

Unplug both cable harness connectors on the alternator. Check them for any damage or burning.
Check if the W/BK wire has come unlatched and backed out in one of the connectors so that it is not making contact.
How do the alternator side of the connectors look?

To check for the stator voltage, either "back probe" the W/BK wire at the connectors or pierce the wire insulation.
Some test lights come with a sharp probe for piercing wire insulation.

NAPA web site shows replacement cable harness connectors for both the alternator output and the regulator.
They also show replacement regulators.