The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > General Truck Forums > Electrical

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 04-30-2019, 03:26 PM   #1
6768chevylover
Registered User
 
6768chevylover's Avatar
 
Join Date: May 2007
Location: nepa
Posts: 734
Crazy alternator

I had noticed my voltage gauge on my truck was reading around 10.5 to 11volts. When I put the voltage meter to the wire, it fluctuated readings from 12.8 and under. I tested the alt. wire and it was doing the same thing. Even the coil wire too but, some wires were steady at 12.5.. Is this a bad alternator? or a connection somewhere? Ask me whatever you need to know...
6768chevylover is offline   Reply With Quote
Old 05-01-2019, 08:58 AM   #2
rpmerf
Registered User
 
rpmerf's Avatar
 
Join Date: Feb 2011
Location: Parkville, MD
Posts: 610
Re: Crazy alternator

Do you have a generator and voltage regulator, or have you swapped to an alternator? If you swapped, how was it done - jumper kit, or cut & crimp the wires? What alternator is in there - 10SI, 12SI, CS?
__________________
1970 C20 Custom Camper 350 / TH350
rpmerf is offline   Reply With Quote
Old 05-01-2019, 09:47 AM   #3
6768chevylover
Registered User
 
6768chevylover's Avatar
 
Join Date: May 2007
Location: nepa
Posts: 734
Re: Crazy alternator

its a 10si,100amp.. I had installed an painless wire harness kit on the truck but modified it alittle to where I have a power post off the alternator power wire on the fire wall. I'm using a three wire set upon alt. with a diode in the line that goes the reg. to the power post because I had run on..
6768chevylover is offline   Reply With Quote
Old 05-01-2019, 12:38 PM   #4
rpmerf
Registered User
 
rpmerf's Avatar
 
Join Date: Feb 2011
Location: Parkville, MD
Posts: 610
Re: Crazy alternator

You have 3 wires on the alternator.

The big lug should be at about battery voltage.
#1 is connected to the dash light. This needs to provide 12v to the alternator when the key is on.
#2 is the reference. This should be connected to a junction. It CAN be hooked to the lug, but that is not recommended. If this is grounded, the alternator should put out like 16V or more. This wire should be at battery voltage.

Might be worth pulling it off and running it down to your local auto parts store for them to test it.

I would certainly start by looking for any bad connections between the alternator and battery.
__________________
1970 C20 Custom Camper 350 / TH350
rpmerf is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 08:53 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com