Discussion:
Alternator Wiring Diagram?

There is a 3 wire plug on the alternator, I assume one goes to the lamp in the dash, one goes to battery positive, and the other goes to the run position on the key switch? On the truck in question, it has been killing batteries and alternators. When I got to the truck, the battery was boiled dry, at only 10.2V, and the alternator was drawing 160ma of current with the truck off. After looking over the wiring, which is an absolute mess from several hack technicians working on it, I found an odd wiring arrangement. One wire goes to the dash, another to a 10Amp fuseable link to the battery, and the third goes through half a dozen butt splices and ends up at the battery positive terminal. Seems to me like that wire should be going to the keyswitch. Could this wiring arrangement be causing battery drain, which in turn causes the alternator to increase its field current, in turn putting out a higher charge to the battery, thus boiling it dry and straining and eventually killing the alternator? Or am I way off base here?
  • Posted 2 Jun 2012 09:11
  • Modified 2 Jun 2012 09:12 by poster
  • By yaleford
  • joined 2 Jun'12 - 3 messages
  • Ohio, United States
Showing items 1 - 3 of 3 results.
Ok, I will correct the wiring when I return. Thanks guys. As for the email address thing, does this forum not do the Private Messages? This is a VERY strange format forum for me, I have never seen one set up so stone-age like this. It's a bit tough to navigate.
  • Posted 2 Jun 2012 21:08
  • By yaleford
  • joined 2 Jun'12 - 3 messages
  • Ohio, United States
I think all your assumtions are correct. L goes to lamp on dash, S goes to the 5A fuse in the box that is hot all the time, IG goes to the 7.5A fuse in the box that turns hot when the key switch is on.
  • Posted 2 Jun 2012 12:12
  • By mrfixit
  • joined 11 Dec'08 - 1,434 messages
  • New York, United States
do you have a email address to post in your profile,in case anyone had any info for you....
  • Posted 2 Jun 2012 09:43
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States

Post your Reply

Forkliftaction accepts no responsibility for forum content and requires forum participants to adhere to our rules of conduct. Click here for more information.

If you are having trouble using the Discussion Forums, please contact us for help.

Crown RR5225-30TT321
Braeside, Melbourne, Victoria, Australia
Hire
Taylor T650L
Morgantown, Pennsylvania, United States
Used - Sale

PREMIUM business

Noblelift
Global leader and manufacturer of high quality electric, lithium-ion, and IC material handling equipment.
Global Industry News
edition #1237 - 3 July 2025
While innovation and new technology are evolving at what seems to be an ever-increasing pace, the need to capture the data (telemetry) from this tech, and the ability to utilise it (telematics) for efficiency and cost savings, is one area attracting more and more attention ... Continue reading
Upcoming in the editorial calendar
WIRELESS CHARGING
Aug 2025
MANAGING MIXED FLEETS
Oct 2025
Latest job alerts …
Saratoga, United States
East Syracuse, United States
Columbia, SC, United States
Indianapolis, IN, United States
Upcoming industry events …
October 6-9, 2025 - Detroit, MI, United States
October 6-9, 2025 - Detroit, MI, United States
November 14, 2025 - Melbourne, Australia
Movers & Shakers
Jeannette Walker Jeannette Walker
CEO, MHEDA
President, European Rental Association (ERA)
Chief marketing officer, JLT Mobile Computers
Chief executive officer, East Penn Manufacturing