I don't know what is doing it or why, but something is draining my battery overnight. I put a brand new Optima and over night it just turns up dead. It's happened twice now, one with an old Optima and a new Optima, both dead flat. And nothing gets left on or left open. I am wondering if it is the factory alarm system, because the light flashes every few seconds.

I don't know, its boggling my mind.

 

It's most likely audio, security, or lighting installation from someone.

 

start by googling "parasitic draw test" you only need a digital multimeter.

start pulling fuses untill the drop goes down. mostlikely the factory alarm. i had a bad switch causing my battery to die.

 

It has no radio, and the wiring has been sorted out. I just am really set on it most likely being the security. What would be the first thing I should be looking for in terms of it causing the battery to drain? When I initially lock the door from the inside, the system arms and the light stays on for about 5 seconds. Then it flashes a few times and then after that it flashes every once in a while. I have a hard time believing that would cause the battery to go completely flat after just one night.

edit: just saw your post J5sense when the page refreshed with my post. I will try that out.

 

It won't, when its in proper working order. Obviously something has failed, you just have to do the fun task of finding it.

Get a Digital Multimeter(DMM), set it to amps, disconnect the battery cable, connect one lead of the dmm to the battery terminal, and one to the disconnected cable. Now give it a minute or two to sit like that. Note the amp draw, now start pulling fuses until amps drop. The general spec iirc is something like <0.05 amps.

Once you narrow it down, look at the wire diagrams from the FSM, and start unplugging things until you find the source.

 

^ This is what I did when I had a bad battery drain...

Remove the negative battery terminal, set a multimeter to AMP current (mA), one prong to the negative car terminal, one prong to the negative battery terminal, BE SURE ALL ELECTRICAL LOADS ARE OFF, now see if the multimeter is reading very very little current (mA) or zero... If it is displaying more than it should be, remove the 60A BTN fuse from the engine fuse box (so that you can open the door of the car without the lights coming on), go into the car and start pulling fuses from the fuse panel by your feet, one at a time. If that fuse doesn't get the multimeter to display zero, then put it back in and try another fuse. You can also try pulling other things... The way I found my drain, was by unplugging my turbo timer. The multimeter then displayed zero, and that's how I knew that was the problem.

 

if you have an 88 model FC your alt should have N318 or n326 or n332 etc code on the stamp
it will also have a T shaped two pin plug and a B+ post

if instead it has N350 or N370 or n374 or n380 and has a 2 pin plug with parallel pins and weather seal it is a s5 alt
,, which operates with a different field switching circuit that is incompatible with 88 wiring

having the wrong FC alt on the wrong FC wiring will amount to a trickle that will empty a battery overnight and also an overcharge situation
vichy the other way will lead to an undercharge and an alt that will remain hot after shut down ( with short life )

confirm you have the correct alt for the wring loom before checking anything else

 

Seems simple enough, just repetitive and probably annoying. Will do after I get the car back to school from the emissions site, boy do I have a story for you guys... Check up in the build threads probably tomorrow for my thread to be updated with what happened. Landon303 knows but that's because I called him in a panic.

Thanks for the quick responses guys.

 

I used the same wiring, ecu, and engine accessories from my 87 (pre 87.5 models) when I swapped it into my 88. Could the N326 ECU be causing confusion with the security system of the 88? It originally had the N327 ECU. But like I said, the wiring was swapped out. The only part of the harness that wasn't was on the driver's side, but I didn't think that it would make any difference seeing as how it was all the same. And with the A/C removed, that cleared up a little bit more of the wiring.

On a side note, I did notice while driving it around on friday, after setting my clock I noticed after about 10 minutes it had reset itself back to 1:00 then it flat out disappeared. Could just be the cold solder joints, but who knows.

 

Just a coincidence...probably.

 

S5 or FD alternator?

 

N326 or N327 matters not.

IF you have time on your hands..............pull the BTN fuse when thru driving at night. It feeds the battery buss. Get up the next morning and see if the battery is flat or not. Not flat? Some item on the batt buss is draining the battery.

Still flat? Put the BTN back in. The next day when thru driving for the day, disconnect the alternators output cable. Next morning go out and see if the batt is flat or not. Not flat? Alternator is the problem.

IF you had a meter that measured amperage you could find the problem quickly. But you dont' so no sense writing about it.

 

it matters lots which alternator is attached to which field wiring and the issue is identified and well documented as the most common cause for battery issues
as such i have quoted the correct manual alt part numbers,, am yet to see a n327 ( auto ) alt
( or n319 or n351 )

trickle is what happens when you connect an alt with an always live field ( s5 ) to wiring that has its field switched via the key on circuit ( s4 )
basically this amounts to having your reds ( key on ) circuit being fed B+ backwards from the reg via the ( wrong ) field wiring when the key is out

 

To perform a proper parasitic draw test, you must put all modules to sleep, open and close all doors. You must disconnect the negative cable but hold it to the terminal, I like to keep a gear clamp nearby, hold the gear clamp to the cable and quickly slip it over the terminal on the battery. The goal is to not break connection while hooking up the meter, the meter completes the circuit. While doing the above the meter must be connected to the gear clamp over the terminal and the cable. You may see 200-400 mA from some security systems functioning, 0.5 A or above will drain the battery. Wait approximately 30 minutes for all modules to go to sleep, after that time measure the current. If you have an excessive draw, pulll fuses one by one until you've found the circuit the drain is on. This procedure is exactly the Ford dealer procedure.

 

My issue was the headlight retractor motor. It l locked and killed 2 brand new batteries. Took out that fuse and no more issues. Luckily both batteries were replaced for free under warranty. Good luck.

 

-_-

One of my headlights are stuck about 1/4" from full close... I never thought that to be the issue, nevermind the fact that my battery dying started AFTER my headlight got stuck.

Ugggghhhhhhh

 

I'm glad you found the cause. Whats the emissions story? I love hearing those.

 

making a thread now