Hi every one,

I'm new to the forum but it seems like a good place to ask this. I have a parasitic draw somewhere in my truck. When performing the draw test I get ~0.5 Amps of draw, after removing cab fuse 26(10 A fuse) this goes down to about 50 milli Amps after all the capacitors charge. The problem is fuse 26 doesn't do what fuse 26 says it does in my "hanyes" mechanic manual. The real circuit seems to operate the anti theft, door open w/ keys in ignition chime, windshield washer fluid and windshield wipers. I'm inclined to think the draw is due to the anti theft system as it is the only thing that is on when the truck is not. The theft light blinks in 3-5 sec intervals and turns off when I start the truck. I've struggled to find info on the actual circuit so I could go through and un plug things to find the exact culprit and I'm new to working on truck electrical systems I was wondering if anyone else has had this issue and/ or has experience solving it, or if someone has the actual circuit diagram on hand.

Truck is a new to me 2001 ford ranger 4L SOHC, seems to previously been a farm truck

TL:DR
Have parasitic draw, think it's due to anti theft system, need to know how to disable system or correct parasitic draw.

 

Welcome to the forum

Go here to get your 2001 owners manual: https://www.ranger-forums.com/genera...1-models-3747/

Pages 162-164 tells you what cab fuses are for what systems

Fuse 26 in the cab is for GEM module's timer and battery saver relay, so will always need power, not for anti-theft

When you turn off the key, pull it out and all doors are closed, the GEM module timer STARTS
After about 20-30 minutes timer will open Battery Saver relay cutting power to any cab lights, then GEM goes to sleep until a Door is opened or Fob is used to unlock a door

So you can't really test drain until you wait 20-30min with doors closed

And yes, Ranger should only draw .03 to .07 amps after GEM goes to sleep
This power is for PCM(engine computer) memory, radio/clock memory, keyless entry(if so equipped), and GEM trigger so it wakes up when reactivated

The battery saver relay is in a relay box above gas pedal area under dash, relay box 1
If you want you can find it and pull it out and then test amp draw, to see if it drops, relays draw about .4amps, so that could be the .5 amp draw you are seeing so pulling fuse 26 and seeing drop .05 amp draw means there is no parasitic draw

If your battery dies sitting over night then its most likely a battery issue, its self draining, common issue after 5 to 6 years old
You can test a battery with volt meter
Battery must sit for 4 hours before testing
12.8volts is a new battery
12.5v is a 3 year old battery
12.3v is a 5/6 year old battery and time to shop for battery sales

12.2v or under is a bad battery
If you put volt meter on battery and you can watch volts slowly drop then battery is self draining, it has in internal short in one of the cells


Test alternator
After startup battery should show 14.3-14.8volts
After driving or idling for at least 10minutes, and without shut engine off, it should show 13.5-13.8volts, UNDER 14volts, over 14v for more than a few minutes will COOK a 12v battery
Turn on all lights, and heater fan to high
Should still be 13.5 to 13.8volts
All is well

 

Thanks for the the reply, and just to make sure all my duck are in a row:

This is my 3rd new battery in a year, the last two I had to contentiously recharge until they gave bad battery voltages and I had them returned and replaced under warranty. So I know something is draining the battery when the truck is off.

Now currently I have a brand spanking new battery that sits at 12.8 V, and I had Autozone use their fancy testing gadget to test my alternator so I'm inclined to think my alternator is good. And I'm not seeing a 0.05A drop I'm seeing the current go from 0.5 to 0.2 over about a 5 minute window when fuse 26 is in and the current going from 0.2 to 0.05 over a 5 minute window.

'll double check with the above tests you mentioned, but unless I've been very unlucky with my batteries and or Autozone messed up the test I'm still inclined to think I have a parasitic draw problem

 

You can go thru a few batteries before you get a "good one" just FYI, cheaper batteries can get internal shorts as soon as you start to use them

.05amps is 50ma which is fine for any vehicle when its sitting
.5 amps isn't but wouldn't drain a car battery overnight, would take a week or two

The battery is ONLY used to start the engine, then alternator takes over all electrical power, it runs at a minimum 13.5volts, so any voltage runs TO the 12.8v battery, so battery stays charged up for the next time it is needed
YOU need to test alternator with YOUR volt meter

Most car batteries are rated in CCA, cold cranking amps, you can get the Amp/Hours(ah) from that by multiplying by .7
So Battery with CCA of 500 x .7 = 350ah, this means battery will be dead with 1 amp draw in 350 hours, or with a .5 amp draw it will last 700 hours(29 days) before its dead
Or .05 amp draw 7,000 hours(291 days)

But dead is different than not enough AMPs to operate starter motor, which of course happens sooner than dead, lol
Starter motor should draw 60amps, but you need to test this, because your problem may be battery cable or starter motor issue

You can disconnect the coil packs 4 wire connector, so no spark
Then put volt meter on battery
Have some one crank the engine and count to 10 while you watch the volt meter
It should NOT drop below 10volts during cranking
Do it a couple of times
If it does then battery cables or starter motor is causing too high of an amp draw

 

Ok so, I did everything but the crank test ( gonna try an mac gyver a way to do that solo later)

Battery voltage: 12.5V (after 3 days of trying to debug and a few drives)
also voltage dropping very slowly so this battery is probably shorted through (~0.01V / 5 sec)
Voltage over battery on start up: 14.5V
Voltage over battery after 10 minutes: 14.5V
Draw test after 30 minutes: 0.1A

So if I'm understanding your previous post right, this means I have an issue with my alternator which fried my battery when I go to drive it. Which would also make sense why I thought parasitic draw, cause the battery saver circuit is shorted through the battery. So is this as simple as swapping the alternator for a new one or is this a more in depth problem?

 

Yes, could be alternator "cooking" the battery, but.......................

If battery is self draining then alternator's voltage regulator doesn't get the "pushback" from a charged up battery, then it can stay above 14volts

The voltage regulator measures "pushback"(electromotive force), when you first start the engine the battery is drained, so only has a little "pushback" and voltage regulator keeps voltage above 14volts for fast recharge
As battery gets fully charged it starts to "pushback" voltage, so voltage regulator reduces voltage in the system to under 14volts

When you turn on the headlights the "pushback" drops, you would see a drop in voltage, then the voltage regulator responds and turns up voltage so its back to say 13.6volts
Same for heater fan on high, system "pushback" drops and voltage regulator adds more volts to compensate

A voltage regulator does this by varying the voltage it sends to the Rotor of the alternator, it sends 7-9volts to Rotor, the spinning of the rotor by the engine creates a higher voltage, 13.5-14.8volts
A voltage regulator can break and send a steady 9volts so alternator is always over 14volts

But "bad" battery can cause voltage regulator to do that as well


Unhook a battery cable and test battery voltage, then wait 15minutes(or longer) and test again should be EXACTLY the same, if its less battery is self draining


Just a heads up
"Back in the day", lol, it was popular to unhook negative battery cable with engine running to test if alternator was working....................
DO NOT DO THAT
Older external voltage regulators used mechanical relays which were less susceptible to voltage spikes
Internal voltage regulators use transistors which will blow out with a voltage spike

 

Ok so I did that test and the battery voltage didn't change 12.6V (seems to have actually charged by 0.1V with the previous testing),

I also did the alternator test a second time and the initial load was still 14.5V but now drops to 14.1V after 10 min, and 14.0V with everything on blast, I'm not sure what changed.

 

Good news about the battery

Voltage regulator seems to be working as voltage DID drop, so it not stuck on one voltage

Many Rangers have a under hood engine light bulb, do you, and is the bulb unplugged, for testing

You can hook up the amp gauge and see what it reads then wait half hour until GEM opens(deactivates) battery saver relay and goes to sleep to see what it reads then
As said .03 to .07 is spec depending on options


One odd question
Does your speedometer/odometer work OK, nothing odd?

 

No hood light, speedometer and odometer work just fine,

I also tested the amp draw until OEM turned off earlier and the draw drops down to 0.1A when OEM turns off which is still high but less bad, I think I might leave this new battery connected (I've been disconnecting it when not driving) the old brand of battery I was using had issues every 1-2 weeks so, so if the truck starts in a few weeks the battery fixed it XD. Still open to possible fixes assuming it's not the battery.

Thanks a ton for all the help you've been giving!!!!!!!!!!