Electrical Issues
Thread Starter
|
Freshman User
Joined: Feb 2011
Posts: 31
Likes: 0
Electrical Issues
I have an 87 F-150 4.9L and I am having some issues with the battery charging. I have had the alternator replaced and the battery has been tested so both are good, but my voltage gauge reads nothing (it might just not work) and my battery light is now on. When I drive at night with the headlights on it drains the battery after a while so it is not be charging while the truck is running. I have heard people talk about a voltage regulator but I am not sure if I have one or where it might be. I'm also not sure if that's the problem. I would appreciate any help anyone can provide
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
I don't remember if they went to alternators that have built in voltage regulators, but if not, then that's probably it. I had this same issue on my '81 and that fixed it. The voltage regulator is an (approx.) 3in x 3in box on the fender next to the battery. They're about $20 new.
Posting Guru
Joined: Mar 2006
Posts: 1,182
Likes: 1
just thinking out loud-
maybe the trigger wire on the regulator (the one that tells the alternator to start charging) isn't connected? unsure on the '87, but i think these wires were usually green. should be the "I" wire.
maybe the trigger wire on the regulator (the one that tells the alternator to start charging) isn't connected? unsure on the '87, but i think these wires were usually green. should be the "I" wire.
FTE Legend
Joined: May 2008
Posts: 56,542
Likes: 0
From: In my own world
that's a 2 g set up, known for melting the harness that plugs into the alternator.
To test the key wire, it is the green/ red tracer wire. My bet is diode in the alternator went bad from bad connection. You can replace the connection with a harness patch, or go ahead and up grade to the newer 3 g set up. I have been doing that with all my g2 trucks as they start to give me problems.
I have a g3 install thread if anyone is interested in the upgrade, I will look it up, and post a link
To test the key wire, it is the green/ red tracer wire. My bet is diode in the alternator went bad from bad connection. You can replace the connection with a harness patch, or go ahead and up grade to the newer 3 g set up. I have been doing that with all my g2 trucks as they start to give me problems.
I have a g3 install thread if anyone is interested in the upgrade, I will look it up, and post a link
New User
Joined: Feb 2011
Posts: 1
Likes: 0
Trending Topics
FTE Legend
Joined: May 2008
Posts: 56,542
Likes: 0
From: In my own world
Fuseable link, black/ orange tracer, comes off the solenoid
I'll find it and link it when I get home later
I'll find it and link it when I get home later
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
FTE Legend
Joined: May 2008
Posts: 56,542
Likes: 0
From: In my own world
Ok, here is the thread I spoke of. there are others, but this one will give you the basics. The whole thread is a good read, but I started the swap instructions on page 3, or post # 32, depending how you have your browser set up.
https://www.ford-trucks.com/forums/1...ator-help.html
Let me know if you need any other info
https://www.ford-trucks.com/forums/1...ator-help.html
Let me know if you need any other info
Thread
Thread Starter
Forum
Replies
Last Post
Dads76XLT
1973 - 1979 F-100 & Larger F-Series Trucks
50
Oct 13, 2016 05:01 PM
bigperm2
1973 - 1979 F-100 & Larger F-Series Trucks
16
Dec 9, 2008 11:23 PM