Electrical Gurus(Slow Battery Drain)

[cobrapwr]

Slow Battery Drain,
When the car sits for 2 to 3 days, the battery goes dead completely. Listed are steps taken.
1. Tested charging system(New Battery & Alt good)
2. Removed the negative battery cable and put a meter between the cable and the battery post. Shows .39 draw.
3. Unhooked Alternator still .39 draw.
4. Isolated the circuit where the electrical drain is occurring F1.6 (#6 in the battery junction fuse box) protects 12 different circuits...

F2.27 Radio measuring .20

F2.39 GEM measuring .24

I've read on multiple other posts that this level is normal and should not drain battery. Any other tips for troubleshooting would be greatly appreciated.

 

[cobrapwr]

Gotta be some savy troubleshooters out there. Any ideas?

 

[32vApe]

The GEM will powered up for about 30 minutes after the car is shut off. .2 amps for the radio will drain the battery in a couple of days for sure. Hook your amp meter up again and leave it on for a half hour or so, come back and see what it reads.

 

[01BlueCobraVert]

Check how secure your connectors are on the wires that connect the grounds on the battery. A similar issue happened to my buddy and it was because the wires were coming out of the connector. we put on new one on it and the issue was resolved.

 

[cobrapwr]

thx for the ideas. ill give them a shot. willing to try all before paying 80 dollars an hour for repair. any others would be greatly appreciated.

 

[Slow95Cobra]

like stated, leave it a while when checking for the draw. Ford says to wait 45 mins to allow all modules to shut down/sleep. then again its been a few years since ive taken the Battery class...lol

 

[cobrapwr]

Found some great troubleshooting on Ford Forum. Hope this is helpful for any of you who maybe in this situation. Thx again to those with ideas.

You need to measure *amperage* being drawn, not voltage.

You could place your multimeter in current mode, disconnect the negative lead to your battery, then place the multimeter in series between the battery and

the negative battery cable. You will then be able to see exactly how much current is being drawn. When the neg terminal is removed and then re-connected via

an ammeter to the neg battery terminal the PCM will command all system monitors to function and there will be a fairly large draw. The PCM will check for

expected actions and if none are received after 20 to 30 mins or so will command the sensors to go to sleep mode progressively. There will be a large drop

in the amps when all systems are in sleep mode. Then you can start to remove fuses to check for abnormal current draw.

I think the monitored systems need over 200 milliamps to monitor for expected actions with nothing going on and sleep mode should have about 40 milliamps if

all is ok. You cannot open doors or anything in this mode.

You can also have an Alternator diode failure which can quickly flatten a battery.


Next to the electrical drain. I opened the drivers door and left it open, after 10 minutes the lights went out. I proceeded to remove the battery neg cable

and make a copper wire to fit on the battery terminal to hold the red (+) lead of my digital multi-tester. I set the digital meter on the 10Amp setting for

the leads and the dial. I attached the black (-) lead to the battery cable clamp and tightened it to securely hold (ammeter setting does not differentiate +

and - so any connection should be ok). The system woke up with a slight (very small white spark and little click) spark and the interior lights turned on

and the meter registered 2.2 amps draw. After 10 minutes the lights went out and the draw was 1.8 amps and after 15 minutes the draw dropped to 0.240 amps

(240 milleamps), after 30 minutes the draw dropped to 0.174 amps, after 32 minutes the draw dropped to 0.040 amps (40 milleamps), after 35 minutes the draw

dropped to 0.020 amps and every 8 seconds spiked to .040 amps momentarily. The continuing draw of 20 milleamps with a momentary spike to 40 milleamps every

8 seconds untill 60 minutes when I terminated the test. The "theft" light blinked every 3 seconds.

Now with the driver's door open and all systems asleep the appropriate fuses can be removed to check the draw. I do not know the correct sequence, but

suspect that you cannot re-connect the fuse without risking waking-up the PCM since there is a large network of monitors that are all inter-connected. It

would be no fun to start that process over.

If the diode in the alternator has failed and is feeding battery to ground there will be a large draw which will produce a fat blue spark and a loud crack.

This is a serious short. Battery dies in about 5 to 10 hours.


With all the accessories on the car switched off there should only be a small drain on the battery from the PCM and the sensors that manage the safety and

operations of the car. The load should be about 2.2 amps if you have left a door open and only 0.240 amps (240 milleamps) if not and this produces a very

small white spark. The 240 milleamps will drop to 20 to 40 milleamps over the next 30 mins as the sensors are put to sleep if you do nothing to the car.

That rate of discharge will allow the battery to start your car after a month of sitting somewhere.

The overnight drain and blue spark show a large drain on the electrical system. The first suspect is one of the alternator's diodes which may be draining

the battery to ground. Disconnect the battery and put an ammeter between the neg post on the battery and the neg cable and note the reading and disconnect.

Remove the heavy battery cable from the alternator and safely insulate the connection from grounding. Remove the remaining alternator connections to isolate

the alternator. Now reconnect the ammeter and note the reading, if the reading has dropped significantly replace the alternator because you have a failed

diode feeding battery current to ground through the alternator.

If the ammeter is reading between 20 milliamps to about 240 milliamps the problem is solved, but keep it connected to see that after a further 30 mins it

does drop to at least 40 milliamps or lower.

If the reading is higher then one of the car's electrical systems has a problem, but how to find it. Make sure all the electrical systems are switched off

and the driver's door or any access to the fuse panels are open. Disconnect the neg cable from the battery and connect a digital multi-meter set to record

DC amps between the neg battery terminal and the neg battery cable, secure the connections so that they stay connected (i.e. alligator clip, length of wire,

etc). Record the time and the amps and wait for 35 minutes for the PCM and all sensors to go to sleep, but still monitoring. Record the time and amps.

Now you start to pull the fuses that govern the likely circuits causing the drain. However, once you pull a fuse do not put it back because that will likely

wake a sensor and since all the sensors are connected with the PCM you will be back to the 2.2 amp draw due to the GEM (Generic Electronic Module) switching

on the door lights, etc. So keep a record of the circuits disabled, the fuse # and size and where the fuse is now that it is somewhere safe outside the car.

Do it one fuse at a time and keep checking the ammeter to note a change in reading until all the draining circuits are found and the ammeter is registering

40 milliamps or less.

Disconnect the ammeter and repair the circuit, and re-install all the fuses in their correct places as recorded earlier.

Reconnect the ammeter and verify the repair, by watching the ammeter as it shows a reducing amp draw over the 30 minutes after re-connection. If you are

down to 20 to 40 milliamps the problem is fixed and you can reconnect the battery.


GOOD TO KNOW
1999 Ford Mustang Car Security Wiring Diagram

Battery Constant 12v+ Positive Wire (+): Yellow and Light Green/Purple
Battery Constant 12v+ Positive Wire Location: Ignition Switch Harness

Starter Positive Wire (+): White/Pink
Starter Positive Wire Location: Ignition Switch Harness

Ignition Positive Wire (+): Red/Light Green
Ignition Positive Wire Location: Ignition Switch Harness

Second Ignition Positive Wire (+): Red/Black
Second Ignition Positive Wire Location: Ignition Switch Harness

Accessory Positive Wire (+): Gray/Yellow
Accessory Positive Wire Location: Ignition Switch Harness

Second Accessory Positive Wire (+): Black/Light Green
Second Accessory Positive Wire Location: Ignition Switch Harness

Parking Light Positive Wire (+): Brown
Parking Light Positive Wire Location: At GEM (26-Pin Plug, Pin 7). The GEM (generic electronic module) is located above the drivers kick panel.

Power Door Lock Positive Wire (+): Light Green
Power Door Lock Positive Wire Location: At GEM (20 Pin Plug, Pin 20). The GEM (generic electronic module) is located above the drivers kick panel.

Power Door Unlock Positive Wire (+): Purple
Power Door Unlock Positive Wire Location: At GEM (20 Pin Plug, Pin 18). The GEM (generic electronic module) is located above the drivers kick panel.

Door Trigger Negative Wire (-): Yellow/Black and Gray/Red (Right). Use both wires. This vehicle has 2 door trigger wires at the gem module, when connecting

to an alarm system, use both door trigger wire and diode isolate.
Door Trigger Negative Wire Location: At GEM (20 Pin Plug, Pins 13 and 5). The GEM (generic electronic module) is located above the drivers kick panel.

Domelight Supervision Wire: Black/White
Domelight Supervision Wire Location: At GEM (20pin Plug, Pin 3). The GEM (generic electronic module) is located above the drivers kick panel.

Trunk Release Negative Wire (-): Pink/Light Green
Trunk Release Negative Wire Location: At GEM (26 Pin Plug, Pin 25). The GEM (generic electronic module) is located above the drivers kick panel.

Horn Negative Negative Wire (-): Yellow/Light Green
Horn Negative Negative Wire Location: At GEM (26 Pin Plug, Pin 12). The GEM (generic electronic module) is located above the drivers kick panel.

Tachometer Wire Negative Wire (-): Any Wire That Is Not Red Or White/Light Blue
Tachometer Wire Negative Wire Location: At Any Ignition Coil Or Fuel Injectors

Brake Light Positive Wire (+): Red/Light Green
Brake Light Positive Wire Location: At Switch Above Brake Pedal

Factory Alarm Disarm Wire (-): Dark Green/Purple
Factory Alarm Disarm Wire Location: At GEM (20 Pin Plug, Pin 16). The GEM (generic electronic module) is located above the drivers kick panel.

Factory Anti-Theft Wire (-): Ford’s PATS Anti-Theft (Some Vehicles) Transponder System
Factory Anti-Theft Wire Location: Transponder At Ignition Switch Tumbler

 

[Goodlife]

Great info above.
Any convertible guys out there have trouble with a drain occuring after vehicle is sitting for close to two weeks?
The domelight circuit stated above.. is it the same for convertibles (the lights in the rear view mirror?)