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1990 f250 351w battery drain

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#1 Farmboy31297


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Posted 17 April 2015 - 03:41 PM

Hey guys,
I have a 1990 f250 4x4 with a 351w. I bought it about 2 years ago. About a year after I bought it I went to start it and the battery was dead(I had some interior lights, I then removed them cuz I thought that was the problem). After removing them I charged the battery and tried again, no lucky battery was dead. So I went out and bought a new battery, turns out that one had a bad cell. So on the third battery it turned out good, had it in my truck for about a week and then I went to start it and it was dead. I've been reading around and I went and replaced ECM, and also cleaned and redid all my important ground I could see. So after that I let it go and it was perfect for about 3 days, and I went to try and start it and it was dead again. I've tried doing the test between the negative terminal and the negative wire with the meter,first time doing it I had a small reading and tried it the second time and nothing comes up on the screen. I've taken it to get the alternator tested and it tested good that it was charging. Anyone have any other ideas on what to do?

#2 miesk5


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  • Favorite F-Series Year?:1996

Posted 23 April 2015 - 09:35 AM



Battery Drain; "...Disconnect the positive clamp on your battery but take care not to touch the body metal with the wrench when doing this. Now connect an small light between the + terminal and the clamp. Put the clamp on a rag so it can't touch the sheet metal. If any drain is present the light will glow. Or you can check the amount of drain with an small ammeter. An drain of 1-2 Watts can be tolerated. Next pull the fuse for the mechanic clock and the radio. Still any current flowing (light on)? Ok, so you really have a problem. Now start pulling the fuses in the fuse box one by one until the light goes off. This is the circuit in which the problem lies. Check your manual or the indications in the cover of the fuse box to see which systems are connected to that fuse. The next steps depend on the systems concerned. Try disconnecting each one of the parts connected in the circuit. Again it's the same - when the light goes out you've found the problem. Even better than a light bulb is an buzzer. Many people have one of those annoying little rascals lying around. Use it..."
Source: by Alain H


Drain Testing

Check for current drains on the battery in excess of 50 mA with all the electrical accessories off and the vehicle at rest. Current drains can be tested with the following procedure.


CAUTION: Do not crank the engine or operate accessories that draw more than 10A. You could blow the fuse in the meter.

NOTE: Many computers draw 10 mA or more continuously.

NOTE: Use Rotunda 88 Multimeter 105-R0053 or equivalent between the battery positive or negative post and its respective cable.

1.NOTE: Steps 1-5 correspond to the numbers in the following illustration.

Insert the test leads in the input terminals shown.

2.Turn switch to mA/A DC.

3.Disconnect battery terminal and touch probes as shown.

4.Isolate circuit causing current drain by pulling out one fuse after another while reading the display.

5.Current reading will drop when the fuse on the bad circuit is pulled.

6.Reinstall fuse and test components (including connectors) of that circuit to find defective component(s).

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 or disconnecting fuse links to pinpoint the location of the current drain. When the current drain is found, the test lamp will go out or the meter reading will fall to an acceptable level. If the short is still not located, after checking all the fuses and fuse links, the drain may be due to the generator.

Test Conclusion

The current reading (current drain) should be less than 0.05 amps. If it exceeds 0.05 amps it indicates a constant current drain which could cause a discharged battery. Possible sources of current drain are vehicle lamps (underhood, glove compartment, luggage compartment, etc.) that do not shut off properly.

If the drain is not caused by a vehicle lamp, remove the fuses from the interior fuse junction panel, one at a time, until the cause of the drain is located. If drain is still undetermined, remove fuses one at a time at the main fuse junction panel to find the problem circuit.

Electronic Drains Which Shut Off When the Battery Cable Is Disconnected

1.Repeat Steps 1 through 6 of the voltmeter drain testing.

2.Without starting engine, turn ignition on for a moment and then off. If applicable, wait one minute for the illuminated entry lamps to turn off.

3.Connect the voltmeter and read the voltage.

Test Conclusion

The current reading (current drain) should be less than 0.05 amps. If it exceeds 0.05 amps after a few minutes, and if this drain did not show in previous tests, the drain is most likely caused by a malfunctioning electronic component. As in previous tests, remove the fuses in interior fuse junction panel one at a time to locate the problem circuit.

by Ford in 96 Bronco-F-Series Workshop Manual (PARTIAL)
Same as most earlier years exc. for OBD II in 96, 4WABS (93-96); ABS (87-92); Air Bag (94-96); 3 Screw Automatic Locking Hubs (Built from May 95 through 96); Spark Plug Wire Routing & Firing Order (The firing order for 1987-1993 5.0Ls is 1-5-4-2-6-3-7-8. The firing order for 1994- 96 5.0Ls & all 5.8Ls is 1-3-7-2-6-5-4-8.);
2-piece Spindle Rolling Diaphragm Seal (RDS) used on 5/95 to 96 Broncos & F Series 1/2-ton 4WD
and a few other items that I still need to research
96 Bronco, E4OD, Man Xfer Case & Hubs
See my Big Bronco & F Series Technical & Parts LINKS site. Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim! http://schwimserver5.com/?index=1128
Thanks to All Who Serve

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