keep blowing primary battery fuse 20amp - Ford F150 Forum - Community of Ford Truck Fans

1997 - 2003 Ford F150 General discussion on the Ford 1997 - 2003 F150 truck.

keep blowing primary battery fuse 20amp

Thread Tools Search this Thread
Old 12-08-2008, 04:02 PM   #1
Junior Member
Thread Starter
Join Date: Nov 2008
Posts: 11
Thanks: 0
Thanked 0 Times in 0 Posts
Default keep blowing primary battery fuse 20amp

Okay, near the passenger side of truck 97 f1504x4 there is a primary battery fuse that connects between wire on alt and primary fuse block, this fuse blows soon as I install one in the vehicle running or not, has anyone ran into this problem could it be a bad alt? I traced all possible wires and none seem to be grounding out any place and all grounds seem to be making a good ground connection, the truck has a new battery and starter installed prox three months ago, the truck does run and start but with out this fuse in place it will not charge and it runs on battery til it is dead then stops running completely, I traced batery wires, alt wires, starter wires etc, and all lights inside and out seem to be working fine, radio etc all working fine, as well as all power options. do you think maybe something inside the alt is messing it up? thanks for any tips or advice ahead of time!

97f150tim is offline   Reply With Quote
Old 12-08-2008, 06:50 PM   #2
Senior Member
Join Date: Feb 2008
Location: Henderson, NV.
Posts: 4,656
Thanks: 0
Thanked 19 Times in 19 Posts

Yes, power goes to alternators "A" terminal at all times. Take an ohm meter and with alternator disconnected measure the resistance. Your has to be shorted. If an ohm meter is not available, remove alternator and have it tested. Something is wrong inside.
Good old Bill is offline   Reply With Quote
Old 12-09-2008, 11:40 AM   #3
Junior Member
Thread Starter
Join Date: Nov 2008
Posts: 11
Thanks: 0
Thanked 0 Times in 0 Posts
Default problem fixed

Hey thanks for the help, it ended up being a bad diode in the alt, took it off had it tested guy thinks maybe someone reversed polarity durring a jump, probably stupid me, anyhow got a new alt installed and problem fixed... Thanks for the assist and info
97f150tim is offline   Reply With Quote
Old 07-17-2012, 07:11 PM   #4
Join Date: Jul 2012
Posts: 94
Thanked 0 Times in 0 Posts

hi im haveing a simular problum but not the same i just had some new spark plugs put on and at that time we lost a tool down in side the engine so we had to remove the alt. and primary fuse box looking for the lost tool im afraid tha maby we didnt hook up the primary fuse box back up corectly because the to red power wires go to one bolt on the right side and the bolt next to it has nothing on it i downloaded the user manul both the power network box mega fuse and alt. mega fuse have red wire sticking out the left side goingto the same bolt and im not sure if that right im thinking the alt. mega fuse red wire might need to go on the bolt on the left insted but not sure

i have just installed new spark plugs and new battery at first i tryed to turn it over and nothing but then after letting it charge for a wile i get a click when turning the key it sounds like the click comes from the primary fuse box

My truck wont start i cant figure out whats wrong its driveing me nuts can anyone help?

A picture of the wireing for the primary fuse box would help.
jackrabbit72380 is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
puddle/cargo light not working cajunwaternut Lighting 1 07-10-2017 07:21 PM
Electrical Issues? AdvanceTrac & Hill Descent Control mildjar Maintenance Shop 4 06-19-2016 11:54 AM
"Key on" 12v source MGF 2015 - Present Ford F150 9 01-18-2016 03:25 AM
When its raining my truck goes crazy DezertRat 1997 - 2003 Ford F150 7 09-27-2015 01:08 AM
1983 F150 backwards battery johncarroll297 Maintenance Shop 0 09-18-2015 01:10 AM

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

All times are GMT -4. The time now is 07:58 PM.

Copyright 2006 - 2017 We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: