Factory alarm draining battery.

How do you know what is draining the battery? It could be a lot of things or just a weak battery.

I already went though all the fuses with a multimeter with the alternater and starter disconnected. The engine management fuse was drawing 160 miliamps with every thing off. I disconnected the power plug going to the alarm and the voltage dropped to 3 miliamps.

Also the car has a new battery alternater and starter because previous owner could not find the drain and started there.

I'm guessing the alarm system is not going to sleep like it should or it's waking up from a door lock, ignition or what ever not working right. But I don't know I'm guessing on how it all works.

160 milliamps is not very much but that may be it. I would check to make sure your battery voltage is 12.5 or better and that the alternator is putting out enough power (14.5 V +/-). Use your multi-meter to check

160 miliamps IS too much. The industry standard is no more than 50 miliamps on any circuit.

Yes I've checked alternator voltage and battery. The only drain I can find is the 160 like previously stated. Unless it's something spurratic it's the only thing I see out of the ordinary. This car is not being drove. And battery won't be completely drained after three days but low enough the car won't start. I've left the alternator and starter disconnected for the full three days with the same results.

This 160 miliamp circuit is your issue. Fixing it is the hard part. I would disconnect your negative side as to not ruin your battery if it is not being driven.

Do you have an ECM power relay? If so have you checked that for high resistance with 12V supplied to it? I would get a wiring diagram and see what is on that circuit and what it supplies in the fuse box. A bad relay can cause a parasitic drain. Is the alarm system aftermarket? If so how was it wired or with what other circuit? Something as simple as a switch that is on while car is off (even though there is no functionality from its control item) can be a parasitic drain. I am saying this in case it is aftermarket and they wired it on another circuit.

The alarm is factory. That's a good answer for the relay I'm pretty sure it does. But I have gotten the draw to disappear by unplugging the alarm control box. I'm pretty sure the alarm is staying awake. It should shut down after a few min. Or hours of no use. I think something door lock or ignition is keeping it active. I've checked the draw and it's not always happening.

I was thinking door switch is keeping alarm awake. Do you have a door open symbol on your dash when you think all the doors are closed? I know this sounds simple but it may be happening. Bulb burned out on dash? Open a door and see if it illuminates.

That's another good question. I just checked and yes the bulb is good and appears all the door switches are working. Now I have a even more complicated question. Is the control box married to my chipped ignition keys and is it married to the cars computer. The alarm control box has a letter code sticker on it that I don't know what it represents. I have found used control boxs on eBay sometimes fairly cheap. Would it be a strait replacement other then reprogramming the fobs. They never have the same letter code on them.

I just read online that the Ford Focus alarm modules do have issues with them not going to sleep.

I read again that a bad ECM power relay will keep the alarm system constantly powered. For your own diagnostic surety and cost savings, I would be testing that relay and any others associated with this alarm system. Test for control and resistance. I know you said you unplugged the module but a constantly powered relay will keep 12V on a component.

I will check the relay. My f150 had a relay go out on the computer also. Luckily it was stray forward didn't work and not cause a drain. My wife has a 2006 focus she drives daily has the same alarm control box. I wonder if I could switch them to narrow down if it the controller or just not a door switch etc.

1 amp will kill a battery fairly quick

I might have the same. 2018 Focus. Sudden battery drain.

Also have alarm

I heard a noise like my clutch with staying on. Sometimes after a long while I hear it electrical shift under the hood. Thought it was my clutch or something. Something seems to be staying on. Seem to hear some sudden release of some electrical components. Like maybe the clutch is staying on

Had a 2002 Kia and the radio amp was draining the battery. Had to replace the radio. Fixed it

I think it might be this. You need an ass kicking battery. If it's not really strong. Something doesn't work right and causes a drain on the battery.