My 1999 F-250 SD 4X4 dome light is flashing as if it were hazard lights. I drove it back and forth a bit today to do some chores around the property without an issue. I hooked it up to my ATV trailer to test the lights and air up the tires and pulled it up 50 feet to my compressor.

I turned the truck off, but left the key on so that I could check the lights, and began filling the tires. Once the tires were complete I went to the truck and hit the hazard lights, i don't remember if the truck was throwing fits when I got to it, or after I hit the hazards switch.

Now the Dome light flashes unless I hit the hazards lights, then those flash instead. The only other thing I can get to respond to me is the electric locks. Truck won't even try to start.

I've unplugged the trailer, cleaned the posts and clamps until they shined, pulled off the passenger side kick panel and cleaned those grounds until they shined, pulled the terminals off of the battery and jumper cabled to my wife's van (new battery 7 days old), and I get no change. The only extra information I could give to help is that after leaving the batter off of the cables for a long time, I can hook them back up again and the dome light stays on just fine. The moment I touch something it starts flashing again.

Battery measured 12.2 volts, currently 11.9.

Anybody know anything else to try? Thanks...

 

Same exact problem with my 01 f250 SD with 5.4 mine started today haven't got any answers yet, only thing I can add to it is my obd link scan tool with enhanced ford software showed 14 codes 12 B Codes (bcm codes) all relays can't remember which ones but they were faulty it said. Then there was two C codes (chassis codes) and if I'm not mi stake. They where something about raps system. I will scan again tomorrow and post exactly what they are. Hope this helps cause I'm lost. I originally thought it was my gem, why would it all of a sudden throw 12 bcm codes and 2 chassis codes?

 

Well, my problems seem temporarily solved. I was talking to a friend who suggested that the truck is meant to operate on no less than 13V. It seemed that the malfunctioning dome light could have been a sign. (Personally I'd prefer a warning light that said 'Low Battery' to a flickering light and door alarm).

I dismissed her idea at first because I'd hooked up to my wife's van and had the same issues. This time we hooked up her diesel to my battery and charged it a bit. Her truck's electrical system was running at 13.8 volts. We unhooked my truck from hers, measured 13.4 volts, and tried to start my truck. It turned over once, then clicked, (the old sign of a dead battery). Then we hooked her truck up to mine and jump started without issue.

I let it run for 5 minutes. Turned it off, waited 5 minutes, then restarted it like nothing was wrong.

Monday I'll get the battery checked at the local automotive store. I see two theories, bad battery, or I started it too many times in a short span moving things around the property and drained the battery. I'll report back which it was.

Can somebody explain why it's better to shut a truck down at 12.2V than let it try to start slowly? All I can figure is that there must be damage to components at less than 13V, still, makes me afraid to go hunting without a spare battery or jumper pack.

I miss my '68 F-100 sometimes... Only about 10 things to go wrong, easy to figure out which it is.

 

i’m having the same problem, dome light flashing, battery voltage low. do i just need to get two new batteries and call it done?