99 F250 7.3
Open my door there is a clicking, sounds like a blinker coming from under dash, dome light is flashing with the clicking noise.
Turn on headlights, nothing.
Turn on key, nothing.
Bothe batteries readin 12.6 volts.
I hooked up battery charger and charger says battery has internal short, sulfated or something like that. Not sure i trust that charger..
My first instinct is to go get 2 new batteries, 2 maybe 3 years old.
Have had recent problem that comes and goes, the dome light would stay on even after doors were shut, had to take bulb out a few times. It only did that a few times.
Batteries or some other something under dash creating problem??
I havent tried jumping truck off with jumper cables, batteries reading 12.6 it should crank?? Nothing, all goes dead when turn key on.
Thanks in advance guys.
Steve

 

Start by making sure your battery cables are clean and tight on both batteries, at both ends. The batteries cannot be load tested or tested for shorts in the vehicle, they have to be disconnected and tested individually. If you dont trust your charger take the batteries to a shop you do trust and have them individually tested. If one battery is bad they should both be replaced.

Also take a look under the drivers side dash for signs of water leaks. The GEM (which plugs into the back of the fuse panel) has been known to do strange things if it gets wet. It might be responsible for your intermittent dome light problem.

 

Great post, Yes ford had a issue with the windshield glue on the bottom of the glass on drivers side, if you look at the module under the dash just above the parking brake assembly, you will see stains on the black plastic cover, that always is the problem when lights stay on, or the blower motor continues to run, ect. that your first place to look, you mat have to pull module out and give it a good look, take out the two bolts that hold the wiring connectors in from under the hood than the bolts under the dash that holds it in. they give you room to pull it out. If its wet, replace module, but first call safelite and have them reseal the windshield. the problem with the glass is the black paint around the edge of the glass, breaksdown and separates causing the leak, I had them do mine, of course they tell you no warranty for the reseal. they want to sell you new glass but I had no problem with it and its over 2 years old. I bet thats your problem. David 7.3

 

This has happened to me when there was a problem with a battery cable. The batteries were discharged because the corroded cable did not allow the batteries to charge when the engine was running. Then finally when trying to start, I got the flashing interior light and a clicking relay sound from under the dash. The battery voltage was around 12. when no load, but when trying to start, there was no juice available.
So I vote with a battery or cable problem. Larry

 

Wow, that sounds great guys. Thought i had an extreterrestrial problem.
Thanks you guys are Great.

 

Ok Im not real mechanically inclined but can take apart anything, scary....
GEM stands for what? General Electrical Module?
Its BEHIND fuse panel? Have to remove fuse panel 1st?
Bolts under the hood?
GEM i can prob get at a napa store? What brand?

P.S. We have had way more than our share of rain here lately in central Ms.

 

Holy PP. GEM module new is $600. Hopefully thats not my problem?? Where do i get the best price? Find used one from used auto parts? Can they be rebuilt?
Can i take out and try to clean all connections and fuse panel also?

 

Our shop truck does the same thing with the clicking and flashing dome light if the batter is low, or has a bad connection. It almost sounds like a bad connection on one or both batteries.

If you don't trust the charger, take the batteries somewhere to have them tested.

The dome light staying on is likely the switch in the door latch, spray some WD 40 in there and it should make it go away.

 

Thanks Mike, I will definetly go thru all cables and connections before i spring for that GEM mod. Saw no evidence of any water leakage around fuse panel.
I'll be back w results in couple days.
And thanks to everyone else also.
This forum is awsome. Ask question you GET answers.

 

These trucks like their batteries to be in tip top shape. I had the same issue with chattering relays under the dash and hard start. I replaced the batteries and it went away. Have the batteries tested independently and off the truck if all possible. I would also recommend looking at your alternator.

 

Pull door cover and make sure the door plunger isn't making contact with the wire bundle inside.

Just a thought!

 

I stressed out for no reason. I finally got a chance to hunt for problem.
#1 Clean battery terminals just at battery.
#2 PROBLEM SOLVED
#3 Almost embarrassing.
Thanks Guys, True these trucks depend on their batteries and good connections.

 

Glad to see you got it fixed.
I usually start at the simplest solution and work up from there.

It doesn't matter the vehicle, good, clean battery connections are a must, along with a good battery(batteries) for everything else to work properly.