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

parasitic power drain

Thread Tools
 
Search this Thread
 
Old Feb 18, 2025 | 09:03 PM
  #1  
rich1785's Avatar
rich1785
Thread Starter
|
5th Wheeling
Joined: Nov 2022
Posts: 47
Likes: 1
From: Utah
parasitic power drain

Gentlemen,Gentlemen,



I have a parasitic drain on my 85 F350 diesel, It is outside the fuse box. At some point in the trucks life it has had: snow plow, camper and trailer wiring installed. I have removed it all since it was all rotten anyway. It is back to 99% stock wiring. I pulled all the fuses and it still drains over night. If I unbolt the + power to the glowplug relay which of course feeds the starter relay the drain stops. These are normally hot as per the wiring diagram so not sure where to go now. Any ideas?
 
Reply
Old Feb 18, 2025 | 10:54 PM
  #2  
BigBlue2's Avatar
BigBlue2
Lead Driver
20 Year Member
Liked
Loved
Community Favorite
Joined: Apr 2002
Posts: 5,317
Likes: 1,243
Originally Posted by rich1785
Gentlemen,Gentlemen,



I have a parasitic drain on my 85 F350 diesel, It is outside the fuse box. At some point in the trucks life it has had: snow plow, camper and trailer wiring installed. I have removed it all since it was all rotten anyway. It is back to 99% stock wiring. I pulled all the fuses and it still drains over night. If I unbolt the + power to the glowplug relay which of course feeds the starter relay the drain stops. These are normally hot as per the wiring diagram so not sure where to go now. Any ideas?
You have two relays to check. Maybe one of them has a short to ground?
 
Reply
Old Feb 19, 2025 | 06:21 AM
  #3  
tjc transport's Avatar
tjc transport
i ain't rite
Joined: Mar 2005
Posts: 65,507
Likes: 5,565
From: Marlboro Mental Hospital.
Club FTE Gold Member
disconnect the alternator and see if the draw goes away. also could be the voltage regulator.
 
Reply
Old Feb 20, 2025 | 07:49 PM
  #4  
gespeter's Avatar
gespeter
Mountain Pass
Photogenic
Joined: Oct 2021
Posts: 214
Likes: 60
You can connect a 12v tester or tail lamp-size bulb in series with the + battery cable. A drain should cause the lamp to glow. Then disconnect one thing at a time until the lamp goes out and you've found the problem. Completely disconnect one of the batteries. Disconnect positive terminal of remaining battery and insert lamp between battery and cable.
 
Reply
Old Feb 26, 2025 | 10:05 AM
  #5  
rich1785's Avatar
rich1785
Thread Starter
|
5th Wheeling
Joined: Nov 2022
Posts: 47
Likes: 1
From: Utah
I have replaced the starter/glowplug relay recently. I pulled all the fuses and disconected the rear wire harness by the back bumper that shots off the trailer/lic. plate/blinker/rear brake/ rear park lights. No deal still has a drain.

Have not yet changed out the alternator to the 3g but plan on that when I get this figured out. How do I check the voltage regulator?
 
Reply
Old Feb 26, 2025 | 11:49 AM
  #6  
tjc transport's Avatar
tjc transport
i ain't rite
Joined: Mar 2005
Posts: 65,507
Likes: 5,565
From: Marlboro Mental Hospital.
Club FTE Gold Member
unplug it.
 
Reply
Old Feb 26, 2025 | 12:29 PM
  #7  
rich1785's Avatar
rich1785
Thread Starter
|
5th Wheeling
Joined: Nov 2022
Posts: 47
Likes: 1
From: Utah
parasitic saga

ok, that clear and easy. I'm guessing it should not draw power? How do I know to replace it?
 
Reply
Old Feb 26, 2025 | 12:46 PM
  #8  
ihc1470's Avatar
ihc1470
Tuned
10 Year Member
Joined: Jun 2013
Posts: 440
Likes: 61
From: Craigmont, Id
If you are looking for a power drain and with regulator unpluged that drain would go away then regulator would be bad. If just measuring to see what it regulates the voltage to, use a voltmeter and look for around 14.7 dc.
 
Reply
FTE Stories

Ford Trucks for Ford Truck Enthusiasts

story-0

10 Things Every Truck Owner NEEDS (2026 Edition)

 Michael S. Palmer
story-1

Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath

 Verdad Gallardo
story-2

Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

 Joe Kucinski
story-3

2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

 Brett Foote
story-4

Top 10 Ford Truck Tragedies

 Joe Kucinski
story-5

AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

 Brett Foote
story-6

Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

 Michael S. Palmer
story-7

Ford's 2001 Explorer Sportsman Concept Looks For a New Home

 Verdad Gallardo
story-8

10 Best Ford Truck Engines We Miss the Most!

 Joe Kucinski
story-9

2026 Shelby F-150 Off-Road: Better Than a Raptor R?

 Brett Foote
Old Mar 3, 2025 | 01:17 PM
  #9  
rich1785's Avatar
rich1785
Thread Starter
|
5th Wheeling
Joined: Nov 2022
Posts: 47
Likes: 1
From: Utah
That was it, you win the guessing trivia game!

Thanks!
 
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Cparrish99
2011 - 2019 Explorer
2
Sep 12, 2022 06:09 AM
FORD2007EXP
2007 - 2014 Expedition & Navigator
2
Jun 6, 2022 11:25 AM
jeffbradbury7
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
5
Aug 18, 2013 04:37 PM
amos truckalot
1999 - 2016 Super Duty
43
Jun 29, 2010 07:57 AM




All times are GMT -5. The time now is 08:49 AM.

story-0
10 Things Every Truck Owner NEEDS (2026 Edition)

Slideshow: the best gifts for dads & grads

By Michael S. Palmer | 2026-06-02 21:45:57


VIEW MORE
story-1
Rezvani's Latest Post-Apocalytic 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 | 2026-05-30 18:33:59


VIEW MORE
story-2
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-3
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-4
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

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


VIEW MORE
story-5
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

And it might be even better than that.

By Brett Foote | 2026-05-18 19:26:42


VIEW MORE
story-6
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

Slideshow: Does lowering an F-150 Lobo RUIN the ride quality?

By Michael S. Palmer | 2026-05-18 19:20:37


VIEW MORE
story-7
Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Slideshow: Ford's bizarre fishing-themed Explorer concept has resurfaced after spending decades largely forgotten.

By Verdad Gallardo | 2026-05-12 18:07:46


VIEW MORE
story-8
10 Best Ford Truck Engines We Miss the Most!

Slideshow: The 10 best Ford truck engines we miss the most.

By Joe Kucinski | 2026-05-12 13:09:47


VIEW MORE
story-9
2026 Shelby F-150 Off-Road: Better Than a Raptor R?

Slideshow: first look at the 810 hp 2026 Shelby F-150 Off-Road!

By Brett Foote | 2026-05-12 12:50:07


VIEW MORE