Truck was left to me by my father in 2007. I noted right off that if I didn't run it at least every four days max the battery was dead by day five. After some time dealing with this I replaced the battery with the best the truck would take brand new. The issue however continues. And if go five days it needs a jump. Researching the issue on the net I am seeing this issue is not uncommon but haven't seen a solution. Anyone seen this before? No user installed electronics involved that may be causing drain.


2000 Ranger 2.5L 38k

Check the alternator. Its possible its not charging the battery

As you most likely saw in my other post I am suspecting alternator being an issue so I will have them change it out while they are under the hood.

it sounds to me like it is a parasitic drain

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2004 Ext Cab, 4WD, 4.0, Auto, 154k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 7/1/2017)

2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).

The only things I can think of are the constant flashing theft deterrent lamp in gauge area and the flashing red lamp they put in car stereos that flash when head is off.

i think you have a weak battery, my f150 would do that until i put an interstate in there 850 cca never seems weak anymore

the chances of the OP having 2 defective batterys is very small........THE TRUCK HAS A PARASITIC DRAIN......THE LAZY MANS WAY OF FIGURING IT OUT IS TO PULL THE FUSE OF THE SUSPECTED CIRCUIT. IF YOU THINK THE STEREO IS IT PULL THE FUSE.

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do you have any lights ie. on "the airbag" light.

I just noticed the mileage ......that is AWESOME

i DOUBT IT IS THE BLINKING STEREO LIGHT..BUT i JUST NOTICED YOU SAID THE THEFT LIGHT IS FLASHING IS IT SUPPOSE TO FLASH? PULL THE FUSE ON THAT AND SEE IF THE BATTERY GETS DRAINED

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2004 Ext Cab, 4WD, 4.0, Auto, 154k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 7/1/2017)

2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).

I would turn everything off in the truck, take the positive cable off, wait a few secs, and touch it to the battery. If it sparks then you know for sure something is drawing power. Its possible that something is shorting to ground also.

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Ball Joints/Upper A-Arms How To
Replace Door pin/bushing
Repair broken dome light tabs
VIDEO OHC Install

The only lights active with ignition off are fords theft deterrent light and yes its suppose to flash and the non factory stereo red light that blinks for what ever reason. Some kind of deterrent too I assume. Its not mentioned in the manual. Not going to scratch my head any longer its going to the shop for the Pros to deal with it. Oh and the Battery is a year old.

Thanks for all the input and ill post the post op results after they drain my wallet.

I agree the blinking light on the radio/stereo is just a fake anti theft light. I have one on my Matrix..........however the "THEFT" light in the instrument cluster that is flashing. Is it flashing every 2 seconds or is it flashing rapidly when the truck is off....................also check for silly things like the glove box light staying on. etc..............to bad you have to bring it to the "dealer" not all of them are "Pros"...some are "Cons"..

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2004 Ext Cab, 4WD, 4.0, Auto, 154k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 7/1/2017)

2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).

Its flashing I guess about every 2 seconds and there is no glove box light.

Yea it would be nice if i could do it myself but my knowledge base is in 20 years of military aircraft engines, props and other aircraft systems.

Lead Acid Battery chemistry is a 100 year old established science - The battery's partner in crime is the alternator. Very few cars have instrumentation today to correctly interpret how these two components are getting along, just a stupid (because it's cheap and inaccurate) red light.

A freshly charged battery in a corner by itself, no load, will measure +12.6V (temperature will vary it a tiny bit). A failing battery gets sediment between the plates discharging it and reducing the voltage to below +12v.

Assuming a good battery, turn attention to the alternator using a voltmeter on a running engine to measure battery voltage. An alternator with engine at high idle (1000 rpm) will boost the battery voltage to +13.6V or slightly higher. You heard the term 'regulator'...+13.6 is what it's circuitry aims the battery to maintain for best performance and life. At highway rpm the battery should maintain +14V with the headlights on and should never go above +15V with headlights off else water will boil out.

Alternators have 6 diodes in 2 circuits but with one bad the alternator will pump up the battery a bit but never charge it fully yet the 'alt' light won't come on because the circuit is stupid for cost reasons and won't give you the bad news. With the engine just turned off and no loads on, the battery should be +12.6V (+12.45 absolute minimum). Any less and it's not receiving a full charge for the next day's work. If the battery won't hold a no-load 'morning after' voltage above 12.2 V it needs to be changed.

Finding drains when you have some time: I.e. not a work truck. Charge the battery as best possible and remove half the fuses. Note the voltage after 2 days. Replace fuses, (you did make a chart didn't you) recharge the battery a bit, remove the other half of the fuses. Two more days. If you now have found a definate battery voltage difference between the two fuse halves, divide the bad half in two and repeat the test, narrowing down to the components which are the cause of your hair loss. By removing your fuses, you also remove your prejudices about things you 'think' must be or can't be the problem. Everyone should have a decent voltmeter anyway and become accustomed to the few voltages 12.6 and 13.6 and conditions which have meaning in ALL lead acid battery systems. I've not seen a car which can't hold it's juice for a full month vacation and still fire up on the second crank.

Sorry for using so much ink.

Take the groung cable off your battery and clip a test light to the ground cable you removed from the post! Then touch the negitive post with the sharp end of your test light! If it lights then you are pulling power! Have some one start pulling fuses intill the test light goes out! Now you have found what circute is pulling your battery down! NOTE: If your door is open or hood is up and so on then those curcits will be pulling power too!

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1991 Ford Ranger 2.9 4x4

Late follow up: Alternator change fixed the issue. I can now go at least 15 days without starting it and it starts just fine.

Mine has short in wire harness -the red/black from fused ignition to hot in start .It is .17 in run and .40 in Off --anyone got an idea where it shorted . This was tested in the plug that goes to the radio -radio is out of truck. All fuses are ok -must be a short in the wrie somewhere . Radio installed and the battery will gradually go dead and the radio/cd is inopertive. All fuses in side panel and breaker fuses under dash and hood have been checked. 2000 ranger 3.0 ????