Notices
Pre-Power Stroke Diesel (7.3L IDI & 6.9L) Diesel Topics Only

Charging issues

Thread Tools
 
Search this Thread
 
Old Mar 6, 2018 | 09:14 AM
  #1  
wisk's Avatar
wisk
Thread Starter
|
New User
Joined: Oct 2016
Posts: 17
Likes: 0
From: Eastern Oregon
Charging issues

OK Guys, I have another issue that I'm stumped with. 1989 F250 with a 7.3 idi 4x4 5 speed
My battery light on the dash came on and the amp gauage was low on the output, so I checked the voltage output on the alternator and it was low (11.38 volts ) so I replaced it and no changes in the issue. I figured that the voltage regulator may be bad so I drove the 20+ miles to town and stopped into O'Reillys and had them check all the charging parts. After putting the tester on and putting it under load the charging system functioned properly and the battery light went out and the amp gauage showed a proper charge was accuring. 3/4 of the way home the battery light came back on and the gauage showed a low charge again. Thinking I may have a dirty battery terminal I cleaned all four of them and the issue still exists. Does anyone have any ideas on what I should look at next? Any help will be appreciated, thanks in advance.
 
Reply
Old Mar 6, 2018 | 10:36 AM
  #2  
tradergem's Avatar
tradergem
Senior User
Joined: Jul 2007
Posts: 118
Likes: 1
From: Winthrop, Minnesota
I used to have the same charging problems on my 1990 until I upgraded to a 130 amp 3G alternator. Here is a wiring diagram.
 
Reply
Old Mar 6, 2018 | 11:02 AM
  #3  
wisk's Avatar
wisk
Thread Starter
|
New User
Joined: Oct 2016
Posts: 17
Likes: 0
From: Eastern Oregon
This problem just started and I've had the truck for nearly a year with no issues in this area. It doesn't make sense to add amps when everything was fine prior to a couple days ago. Thanks for the input and it may be my solution although I'm hoping that their are others that may have a solution to my problem without having to go through this extensive change.
 
Reply
Old Mar 6, 2018 | 11:40 AM
  #4  
tradergem's Avatar
tradergem
Senior User
Joined: Jul 2007
Posts: 118
Likes: 1
From: Winthrop, Minnesota
I understand what you are saying. I upgraded to the 3G because it helps eliminate connections problems with the external voltage regulator and charges better than the 1G system at low rpms driving around town. The cost was nearly the same for the 130 amp 3G alternator as the 90 amp 3G alternator and allows for improving my stereo system when I get around to it.
 
Reply
Old Mar 6, 2018 | 01:15 PM
  #5  
cadunkle's Avatar
cadunkle
Cargo Master
20 Year Member
Photogenic
Photoriffic
Shutterbug
Joined: Oct 2005
Posts: 2,298
Likes: 27
From: NJ
Changing an alternator and a couple wires is hardly an extensive change. It's a bolt on deal for only marginally more than a 1g or 2g. If you have a 2g, note they tend to melt the wiring and could be a fire hazard. For me at least it's not worth messing with a 1g/2g alternator, when they die or the regular dies I replace with 130 amp 3g. My time is worth enough to myself that I'd rather just upgrade and be done with it.

Aside from that, just the field to +12v and measure voltage, should go up to 16v-17v at full field. Only do this briefly as the alternator will get hot, but it verifies the alternator works.
Check that the regulator is getting full battery voltage at the key on 12v battery terminal (A)
Check that with key on you are getting near battery voltage at the key on 12v terminal (I)
Check voltage at the field terminal output on the regulator (F) and at the alternator field terminal when voltage is low. You should be getting full battery voltage at both. If you have that at the regulator output terminal but not at the alternator, replace the wire. If the other terminals on the regulator check out but you don't get full voltage at field while battery voltage is low, the regulator has failed.
 
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
iexplodez
1999 - 2016 Super Duty
50
Mar 10, 2017 06:01 PM
04X
Electrical Systems/Wiring
3
Apr 9, 2009 10:34 PM
howman442
1987 - 1996 F150 & Larger F-Series Trucks
4
Mar 2, 2004 06:10 PM
45mark
Electrical Systems/Wiring
2
Aug 24, 2003 12:50 AM
apg camo
Audio & Video Systems, Navigation, Satellite Radio & Mobile Electronics
3
Jan 14, 2003 06:12 PM




All times are GMT -5. The time now is 11:48 AM.

story-0
Top 10 Fords at 2026 Carlisle Ford Nationals

Slideshow: Top 10 Fords at 2026 Ford Nationals

By Joe Kucinski | 2026-06-09 11:10:08


VIEW MORE
story-1
3 Best / 3 Worst Parts of Modern Ford Ownership

Based on years of owning multiple modern Ford products.

By Brett Foote | 2026-06-09 10:53:36


VIEW MORE
story-2
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches

SPONSORED: From muddy boots to rain-soaked cargo, these upgrades address some of the most common frustrations Ford truck owners face every day.

By Pouria Savadkouei | 2026-06-08 18:50:34


VIEW MORE
story-3
Every 2026 Ford Engine Explained

Here's everything you need to know about every Ford engine available for the 2026 model year.

By Brett Foote | 2026-06-05 12:58:01


VIEW MORE
story-4
10 Ugly Ford Trucks That We Still Kinda Love

Slideshow: 10 ugly Ford trucks that we still kinda love.

By Joe Kucinski | 2026-06-03 09:51:16


VIEW MORE
story-5
10 Things Every Truck Owner NEEDS (2026 Edition)

Slideshow: the best gifts for dads & grads

By Michael S. Palmer | 2026-06-03 15:43:58


VIEW MORE
story-6
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath

Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.

By Verdad Gallardo | 2026-06-03 11:38:36


VIEW MORE
story-7
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

Slideshow: 10 most expensive Ford trucks ever sold on Bring a Trailer.

By Joe Kucinski | 2026-05-27 16:24:34


VIEW MORE
story-8
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

Here's everything that has changed for the latest model year.

By Brett Foote | 2026-05-27 16:17:28


VIEW MORE
story-9
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

By Joe Kucinski | 2026-05-18 19:34:33


VIEW MORE