Battery Drain
Thread Starter
|
4wd Low
Joined: Jan 2023
Posts: 11
Likes: 0
From: Cibolo, TX
Battery Drain
Within the last 30 days, I have had to call my auto insurance companies road service for a battery 'jump' , three or four times AND even had to replace the battery with a new one, as it was 3 years old. Even after that, I had to call and get a 'jump' at least once. I was starting to think about putting my 2003 F150 in a shop, when I think I found the problem. I had even bought a battery disconnect switch, but hadn't installed it. The culprit, I think, is the instrument panel dimmer switch. If it is left in the 'full on' position, even with the key turned off, it was draining the battery as the truck sometimes sits weeks at a time without starting. When I moved the switch off of the 'full on' position, the battery drain stopped. Anyone else had this problem? I have owned this truck 11 years and never had this problem, previously, although I cannot remember whether I had ever had the habit of leaving the dimmer switch in the 'full on' position, before.
Fleet Mechanic
Joined: Jun 2023
Posts: 1,380
Likes: 383
From: WA
Pretty sure I've left my interior light(s) on overnight before but it didn't kill the battery. That's what a "full on" dimmer switch does, turns on the interior lights. In mine I just remember the dome light turning on, hard to notice in the day light. If you left them on for a few days it probably would drain the battery.
"PANEL DIMMER CONTROL
Use to adjust the brightness of the
instrument panel and all applicable
switches in the vehicle during
headlamp and parklamp operation.
Move the control to the full upright
position, past detent, to turn on the
interior lamps.
Move the control to the full down
position, past detent, to turn off the
interior lamps."
"PANEL DIMMER CONTROL
Use to adjust the brightness of the
instrument panel and all applicable
switches in the vehicle during
headlamp and parklamp operation.
Move the control to the full upright
position, past detent, to turn on the
interior lamps.
Move the control to the full down
position, past detent, to turn off the
interior lamps."
Thread Starter
|
4wd Low
Joined: Jan 2023
Posts: 11
Likes: 0
From: Cibolo, TX
Battery Drain
I'd certainly agree IF my truck had interior lights, but the only interior lights that it has, are the DASHBOARD lights; NO overhead interior cabin light (which I miss). It doesn't even have the door activated light switches to turn on/off lights when the doors are opened or closed. If the dash lights are LED, which I think they are, I wouldn't think they (alone) would drain a new battery down to ZERO volts.
Fleet Mechanic
Joined: Jun 2023
Posts: 1,380
Likes: 383
From: WA
When you say it doesn't have the dome light do you mean it came from the factory that way, or that the bulb or fixture has been removed?
Regardless, "full on" closes a switch that allows power to that circuit.
Regardless, "full on" closes a switch that allows power to that circuit.
More Turbo
Joined: Sep 2017
Posts: 574
Likes: 146
My 2003 has a timer. If lights are left on more than 20-30 minutes, they are automatically shut off by the computer. If your lights aren't shutting off when left on then that may be a source of the problem.
If say the cargo light is left on and does go off after 20-30 minutes, then you have a problem elsewhere meaning there is a parasitic drain. Start checking fuses to see if power is present when it shouldn't be.
If say the cargo light is left on and does go off after 20-30 minutes, then you have a problem elsewhere meaning there is a parasitic drain. Start checking fuses to see if power is present when it shouldn't be.
Fleet Mechanic
Joined: Jun 2023
Posts: 1,380
Likes: 383
From: WA
I was aware of the timer but not sure it applied to that interior light. I have a vague memory of getting in the truck and seeing that the light was on.
Really though, overall, on a 2003, you could just connect an ammeter at the battery terminal, turn the dimmer switch to "full on" and see how many amps are drawn. Do the same with it off. If there's no extra draw then the dimmer switch would not be the cause.
Really though, overall, on a 2003, you could just connect an ammeter at the battery terminal, turn the dimmer switch to "full on" and see how many amps are drawn. Do the same with it off. If there's no extra draw then the dimmer switch would not be the cause.
Last edited by BareBonesXL; Aug 22, 2024 at 02:19 PM. Reason: spling
Lead Driver
Joined: Sep 2002
Posts: 9,551
Likes: 2,034
From: North Texas
Also could be weak charging off the alt due to corrosion on the cables. I had this happen on a Volvo where the drop was around 1.0V from alt to battery.
Easy to check also 100% agree amp draw test.
Easy to check also 100% agree amp draw test.
Trending Topics
Thread Starter
|
4wd Low
Joined: Jan 2023
Posts: 11
Likes: 0
From: Cibolo, TX
Battery Drain - Dome Light
My mistake. My 2003 F-150 XL supercab with standard trim, DOES have a DOME light, even though it hasn't worked in so long that I had forgotten about it. It may just be bad bulbs in the light. It seems like I changed the bulbs, years ago, but the light still didn't work. The light has two separate rocker switches, left and right, to turn on the light, so I didn't know the dimmer switch on the dash was connected. Either way, I had never had a battery drain problem with this truck in the 11 years that I have owned it, prior to the last month. The truck has just shy of 200,000 miles on it and the only repairs that I have made in 11 years is replacing the rear main seal, once, and the present battery is the third battery in Eleven years It has the V6 and automatic transmission.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Thread Starter
|
4wd Low
Joined: Jan 2023
Posts: 11
Likes: 0
From: Cibolo, TX
I do believe the dimmer switch was the culprit, as since I quit leaving it in the 'full on' position, the drain has stopped. I am going to investigate (again) why the interior dome lights don't work. There are times that I could use a little light.
Thread
Thread Starter
Forum
Replies
Last Post