Make sure you replace Both batteries not just one.

 

You still have to find the 2 amp draw. I have been searching in vain for almost a year. I try to drive the long way home and check with a voltage gauge in the lighter socket to see that it is charging. check your truck in the dark to see if there is a dome light staying on, I had to change the left rear door switch out, but still have my batteries go down over night.

 

So the 2 amp draw was still there after i pulled every fuse and relay.Was there when i disconnected the alt.
How would the would i check the starter for the draw?

 

I'm having the same problem 05 F350 6.0 Batteries good. I disconnected the + term on the batteries and put a multimeter between the +term and the main wiring harness. Key off its pulling 2 amps so I started pulling fuses and relays and nothing changed. I hooked up my OBDII scanner and when I hooked the multimeter up the scanner came on and tried unsuccessfully to link up . . .heres the kicker when I then turned the ignition switch ON the scanner turned OFF.
Also sometimes when i hook up the multimeter as above I hear the fuel pump start up with key OFF
I'm thinking the ignition switch might be the problem but wouldn't the amp draw stop when i took all the fuses and relays out?

sometimes electrical issues on these new trucks can drive a man

 

You could have a leaky diode in the alternator.

 

69cj How do you test for a leaky diode in the alternator?
I'm pretty sure alternator isn't an issue since its disconnected when this is happening.
Could a faulty ignition switch be causing this???

Cmon guys there are some brilliant minds on this site . . . lets do this!!
Bismic
Blade 35
Bpounds
and so many more.
Yeah it's a complicated problem and I'm out of ideas to try .. . anyone??

 

The Location of the Problem Can/Will Dictate Wether or Not a Fuse/Relay Being pulled will Stop the Parasitic drain from occuring

Also there is a Fuse/Relay box in engine did you pull anything there??


To Exicute the Battery Drain test Properly you must wait long enough for the Truck (GEM Module IIRC) To go to Sleep before the Test is Done




What is the exact problem you have???

 

Battery


- Drain Tests

NOTE: No production vehicle should have more than a 50 mA (0.050 amp) continuous draw.


Check for current drains on the
battery in excess of 50 milliamps (0.050 amp) with all the electrical accessories off and the vehicle at

rest. Current drains can be tested with the following procedure:


WARNING: Do not attempt this test on a lead-acid
battery that has recently been recharged. Explosive gases can cause personal

injury.

CAUTION: To prevent damage to the meter, do not crank the engine or operate accessories that draw more than 10A .

NOTE:

Many modules draw 10 mA (0.010 amp) or more continuously.


Use an in-line ammeter between the
battery positive or negative post and its respective cable.

Typically, a drain of approximately one amp can be attributed to an engine compartment lamp, glove compartment lamp, or

luggage compartment lamp staying on continually. Other component failures or wiring shorts may be located by selectively

pulling fuses to pinpoint the location of the current drain. When the current drain is found, the meter reading will fall to an

acceptable level. If the drain is still not located after checking all the fuses, it may be due to the generator.


To accurately test the drain on a
battery, an in-line digital ammeter must be used. Use of a test lamp or voltmeter is not an

accurate method due to the number of electronic modules.

Make sure the junction box/fuse panels are accessible without turning on interior and 1. underhood lights.

2. Drive the vehicle at least five minutes and over 30 mph to turn on and exercise vehicle systems.

3. Allow the vehicle to sit with the key off for at least 40 minutes to allow modules to time out/power down.


Connect a fused jumper wire between the negative
battery cable and the negative battery post to prevent modules from

resetting and to catch capacitive drains.

4.


5. Disconnect the negative
battery cable from the post without breaking the connection of the jumper wire.


NOTE: It is very important that continuity is not broken between the
battery and the negative battery cable when connecting


the meter. If this happens, the entire procedure must be repeated. Connect the tester between negative
battery cable and the

post. The meter must be capable of reading milliamps and should have a 10 amp capability.

6.

NOTE: If the meter settings need to be switched or the test leads need to be moved to another jack, the jumper wire must be

reinstalled to avoid breaking continuity. Remove the jumper wire.

7.

NOTE:

Amperage draw will vary from vehicle to vehicle depending on the equipment package. Compare to a comparable vehicle for

No production vehicle should have more than a 50 mA (0.050 amp) draw.


If the draw is found to be excessive, pull fuses from the
battery/central junction box one at a time and note the current drop.

Do not reinstall the fuses until you are finished testing.

8.


Check the wiring schematic in the wiring diagram for any circuits that run from the
battery without passing through the

battery/central junction box. Disconnect these circuits if the draw is still excessive.

9.

Battery


- Electronic Drains Which Shut Off When the Battery Cable is Disconnected


1. Repeat the steps of the
battery drain testing.


2. Make sure all doors are closed and accessories are off. Without starting the engine, turn the
ignition switch to RUN for a
moment and then OFF. Wait a few minutes for the illuminated entry lamps to turn off (if equipped).

Connect the ammeter and read the amperage draw. The current reading (current drain) should be less than 50 mA (0.05 amp) .

If the current drain exceeds 50 mA (0.05 amp) after a few minutes, and if this drain did not show in previous tests, the drain is


most likely caused by an inoperative electronic component. As in previous tests, remove the fuses from the
battery/central

junction box one at a time to locate the problem circuit.

 

Thank you Blade 35 for replying
Yes I pulled the fuse's and relays in the under hood fuse panel.
Ok i will try and explain it more thoroughly I know how these things require every bit of detail to figure out the problem.
When the truck sits for a couple days the batteries go dead and the batteries are just 2 years old so i charged them individually to be sure they were strong. I disconnected the positive leads from the batteries and separated the wire going to the under hood fuse panel and pcm. I hooked up a meter to the positive terminal on the battery and touched the other lead to the (call it the main power wire feed MPWF) MPWF and the meter said it was pulling approx 2 amps. I proceeded to pull the fuses and relays in both fuse panels one at a time and checking the meter after each one . . .no change.
What is strange is with key off and i hook up my OBDII meter to the plug under the dash and touch the amp meter lead to the positive terminal and the OBD reader turns on and tries to communicate with the PCM. it is unable to link up. Then when i turn the key on still hooked up to the code reader and amp meter still hooked up the code reader turns off.
Sometimes when I test the amp draw the fuel pump will come on . . . .
.that should reallly make it interesting for you . .

For some reason i keep thinking the ignition switch is the problem maybe shorting out somehow.
I must also note that the truck will start up ok and runs good but the dead batteries are a bummer.

I hope i covered everything.

 

Mr Blade35
I will use the excellent troubleshooting procedure you posted tomorrow and see if I can find something.
The technique you posted for hooking up the jumper wire to the negative terminal is something i will pay close attention too.
This is just what I needed to get me going again . . thanks

 

Do you have a Bad Hydrometer??? you can test batterys with???

There Probably OK but need to rule them out as Low Power does Cray stuff

The Part with the Fuel pump and Scanner is Odd the Fuel pump is really Odd and you maybe right on track thinking Ignition switch

 

The first scenario is correct -- the OBDII port has continuous power, it's the 2nd one where you turn the key on that's weird cause the port should still have power.

It is somewhat rare, but I've certainly had several vehicles that had weird symptoms that turned out to be the key module itself. I was able to fix most of them, at least temporarily, by squirting WD40 right in the key hole and cycling the key a few times.

I'm hoping the draw you are seeing is from testing while the truck is still powering down. Oh one more: I've also had problems with aftermarket alarm systems and stereos that would do a drain down.

One thing that hasn't been brought up (in this old thread) is that the stock alternators were undersized from the factory. And a "stock" replacement will be too. On my year there was an option for an upgrade to a 140A unit or to dual Alts. I think 140 is minimum on these trucks and look at Benny's sig line for what most folks are going to...

Good luck! I got to hit the road and go visit Mom

 

If I remember correctly, put your digital meter on the battery with the engine running and the voltage scale on ac. If a diode is leaking you will read an ac voltage. If not then the diodes are good. You should only read a voltage on the DC scale.

 

This might be diffrent then what CJ69 is talking about IDK

<table dir="LTR" border="1" cellSpacing="0" cellPadding="7" width="572"><tbody><tr><td height="75" vAlign="MIDDLE">Alternator Leakage Current


To check alternator diode leakage, connect the multimeter in series with the alternator output terminal when the car is not running. Leakage current should be a couple of milliamps at most; more often, it will be on the order of 0.5 milliamps. Use care when disconnecting the alternator output wire; make sure the battery is disconnected first




</td></tr></tbody></table>

 

It is diff. Yours is a current test. Mine looks for ac sine wave voltage that has not been rectified by the diodes.