Keep draining the battery?

Tiny
TERM
  • MEMBER
  • 2000 FORD RANGER
  • 15,500 MILES
Ford Ranger keep draining the battery. Ive checked the alternator which is fine. Seems like something is staying on and draining the battery each night. Where should I start looking and how should I test it. Thanks'

The door ajar light was staying on, but I think I have fixed that. Battery still is draining down and I just put a new battery in it about two days ago.
Thursday, March 29th, 2012 AT 5:23 PM

28 Replies

Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
I have seen the A/C compressor clutch relay stick on which can drain the battery here is the location so you can check it out.

This guide can help as well.

https://www.2carpros.com/articles/car-battery-dead-overnight

Check out the images (Below). Please let us know what happens.

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Thursday, March 29th, 2012 AT 5:37 PM
Tiny
TERM
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Im going to try the parasitic draw test tomorrow evening. I put a new belt on and it was fine, not since the battery started draining it has started to squeal a lot.
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Friday, March 30th, 2012 AT 12:39 AM
Tiny
SATURNTECH9
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If the belt is squealing did you check the belt tenisor?
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Friday, March 30th, 2012 AT 1:16 AM
Tiny
TERM
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I replaced the pulley for the tensioner, should I replace it all?
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Friday, March 30th, 2012 AT 3:06 AM
Tiny
SATURNTECH9
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The pulley only spins the arm is spring loaded thats what keeps the belt tight. Does the belt still squeal?
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Friday, March 30th, 2012 AT 4:11 AM
Tiny
TERM
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Needed a new water pump and belt tensioner, so that is fixed. Now the battery is still draining, and the turn signals have quit working. I have yet to find anything that is draining the battery.
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Tuesday, April 3rd, 2012 AT 4:49 AM
Tiny
SATURNTECH9
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Have you performed a parastic draw test yet?
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Tuesday, April 3rd, 2012 AT 4:16 PM
Tiny
TERM
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Yes, I found that it may be the door switch. The extended door on the drivers side does not latch. Would that cause it to drain the battery.
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Tuesday, April 3rd, 2012 AT 5:47 PM
Tiny
SATURNTECH9
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If it was keeping the dome light on etc then yes it could.
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Tuesday, April 3rd, 2012 AT 7:03 PM
Tiny
TERM
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Fixed the battery drain, disconnected the bottom door latch. Now I need to find a new one. Thanks for your help.
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Wednesday, April 4th, 2012 AT 12:21 AM
Tiny
SATURNTECH9
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Try www. Rockauto. Com or www. Oewherehouse. Com glad to hear you found it.
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Wednesday, April 4th, 2012 AT 3:11 AM
Tiny
FRED HARRIMAN
  • MEMBER
  • 3 POSTS
  • 1994 FORD RANGER
  • 6 CYL
  • 4WD
  • MANUAL
  • 250,000 MILES
I have replaced voltage regulator, battery, and alternaer There seems to be some sort of drain on the battery. I can jump start it or charge the battery, and the thing will run untill you shut it off and than it will not start.
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Monday, May 12th, 2025 AT 8:49 AM (Merged)
Tiny
BMRFIXIT
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If the battery is new and the only way to get it started is with a jump start then you most likely have a connection issue or high resistance in the wiring.

We need to do what is called a voltage drop from the battery to the starter.

https://www.2carpros.com/articles/how-to-check-wiring

Basically this is measuring the voltage that the wiring is using and it should be very little.

So by adding the jump box to it, all you are doing is increasing the amperage so it can overcome any resistance in the circuit.

I suspect we are going to find wiring issues so let's review the wiring diagram below and go from there. Thanks
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Monday, May 12th, 2025 AT 8:49 AM (Merged)
Tiny
FRED HARRIMAN
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I have cleaned the terminals. When I hooked the new battery up there was a small spark. I think there must be an open circuit or something like that. Is there anyway to trace that.
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Monday, May 12th, 2025 AT 8:49 AM (Merged)
Tiny
BMRFIXIT
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BATTERY DRAIN TEST
NOTE: Amperage draw will vary from vehicle to vehicle depending on equipment package.
No production vehicle should have more than a 50 mA (0.050 amp) draw.
BATTERY DRAIN TEST
1. Ensure junction box/fuse panels are accessible without turning on interior and hood lights. Drive vehicle over 30 MPH for at least 5 minutes. Park vehicle and allow to sit with ignition off for at least 40 minutes to allow electronic modules to power down.

2. Connect a fused jumper wire between negative battery cable and negative battery post. Disconnect negative battery cable from negative battery post, without breaking the jumper wire connection to prevent modules from resetting.

NOTE: It is very important that continuity is not broken between negative battery post and negative battery cable when disconnecting battery cable or connecting ammeter. If continuity is broken, go to step 1.
3. Ensure ammeter is set to read milliamps with at least a 10 amp capability. Connect ammeter between negative battery cable and negative battery post. Remove fused jumper wire.

4. If excessive current draw is present (50 mA or more), pull fuses from battery/central junction box one at a time and note any current drop when each fuse is removed. DO NOT reinstall fuses until test is complete.

5. Check wiring diagrams for any circuits that run from battery without passing through battery/central junction box. Disconnect these circuits if current draw still exists. Repair appropriate circuits as necessary.
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Monday, May 12th, 2025 AT 8:49 AM (Merged)
Tiny
52D
  • MEMBER
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Killing a battery within minutes of running? Check for a battery wire thats rubbed the frame, focus on pos cable. Is the car equiped with an amp? Start the truck and trun on lights, is the belt squealing? Is there a squeaking noise? I had an idler pully bearing seizing and about stopped the belt. Also seen alt seize and kill the motor.
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Monday, May 12th, 2025 AT 8:49 AM (Merged)
Tiny
CTULK21
  • MEMBER
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  • 1990 FORD RANGER
  • 6 CYL
  • 2WD
  • MANUAL
  • 100,000 MILES
Hello,

I recently purchased a 90 Ford Ranger for back and forth to work. I needed to bost the truck to take it for a test drive and we all thought it would just require a new battery. So I put in a new battery and it was dead the next day. I charged the battery and then put my meter on it and noticed the volts dropping 0.01 every second. There was/is nothing on in the car and it was not running. What could cause such a rapid voltage drop with apparently no draw? (Grounding problem?). Any help would be appreciated.
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Monday, May 12th, 2025 AT 8:49 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
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Hi there,

Place an Amp meter between Battery Pos(+) and the cable, this will show the true current draw, check with doors closed & key out, allow a small draw for clock radio & ecu memory about.15 Amps if more start pulling fuses & fusible links one at a time, and also disconnect the alternator to check for a faulty diode back feeding, start here.

Mark (mhpautos)
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Monday, May 12th, 2025 AT 8:49 AM (Merged)
Tiny
DAVESMOM
  • MEMBER
  • 5 POSTS
  • 1990 FORD RANGER
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 130,000 MILES
My sons truck keeps draining the battery, even when it is turned off. It was jumped started about a month ago, and has had to be jumped several times since. We put a new battery in it, drove it to town(about 15 miles), it sat in a parking lot for 8 hours and drained that battery too! I do not know much in auto repair. I can not afford to, not do I want to be "taken" on these repairs. Thanks, MOM
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Monday, May 12th, 2025 AT 8:50 AM (Merged)
Tiny
DAVE H
  • MECHANIC
  • 13,384 POSTS
Try this simple test first. To make sure alternator is charging the battery. If alternator is charging then we will need to trace what is draining the battery. Something left on? Radio/interior/exterior lights. Etc. Etc.

TESTING
CHARGING SYSTEM TESTING
NOTE:Ensure that battery is fully charged and battery connections are clean and secure. Check that alternator drive belt is adjusted to proper tension.

NOTE:When charging battery, remove ground cable before connecting charger. If booster battery is used to start engine, negative cable of booster must be connected to vehicle frame. Disconnect negative booster cable first.

Ensure that all accessories are turned off. Connect voltmeter to battery. Attach tachometer and start engine. Operate at 1500 RPM with no electrical load. Voltmeter reading should increase, but it should not exceed 2 volts above battery voltage. Reading should be taken when voltmeter stabilizes.
With engine operating, turn heater or A/C blower motor to HIGH position. Turn on headlights to high beam. Increase engine speed to 2000 RPM. Voltmeter should indicate a minimum of.5 volt above battery voltage.
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Monday, May 12th, 2025 AT 8:50 AM (Merged)

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