Tip & How-To about Acura CL

How to test for a parasitic drain on your vehicle battery

Turn off all lights and accessories and remove ignition key

disconect negative battery terminal

connect an amp meter in series between the negative terminal and negative batery post(have red positive lead go to terminal and black negative lead go to battery post)

now ur meter should read less the .5amp or less the 500 milliamp

some vehicle may have slightly more if they have alot of electronics but .5 amps is good rule of thumb

also remember that the computer systems on many newer vehicles may take up to 40 minutes to go into sleep mode.

so u may want to leave the meter on and come back later to see if it has gone down if it is excessive on initial reading

if u still have excessive draw on the battery start removing and replacing fuses 1 at a time until the reading on the meter drops to within specification.

at that point u know u have found your problem circuit

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3 Answers

battery drains overnight


Car And Deep Cycle Battery

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What causes my battery to drain overnight? Parasitic (or ignition key off) drain is the cumulative load produced by electrical devices, for example, emissions computers, clocks, security alarms, radio presets, etc., that operate continuously after the engine is stopped and the ignition key has been switched off. Normal parasitic loads are below 75 milliamps (.075 amps). When the parasitic load is greater than 75 milliamps (.075 amps), batteries will drain more quickly. Glove box, trunk, and under hood lights that do not automatically turn off when the door is closed or shorted diodes in alternators are the most common offenders. Cooling fans, power seat belt retractors, radios and dome lights left on, alarm systems, and electric car antennas have also caused batteries to drain overnight. Leaving your headlights on will generally discharge a fully charged car battery, with 90 minutes of Reserve Capacity (36 amp hours), within a couple of hours.

It is highly recommended, especially if you are using a sealed wet "Maintenance Free" (Ca/Ca) battery, that you allow it to thaw if frozen, fully recharge it in a well ventilated area with an external battery charger, remove the surface charge, and load tested both the battery and the charging system for latent damage from the deep discharge. You could have a damaged or bad battery. If the alternator is warm and the engine is cold, then check for a shorted diode in the alternator.

Below are some methods that are used to test the parasitic load with the engine NOT running, under hood light disconnected, all accessories switched off, and the vehicle doors closed:
  • Connect a 12-volt bulb across the positive and negative battery terminals to test the bulb and the battery. If it glows brightly, then remove the negative battery cable and connect the bulb in series between the negative battery cable terminal clamp and the negative battery terminal. If the bulb continues to glow brightly, then start removing fuses or connections to the positive battery post one-at-a-time until the offending electrical component is identified by the bulb dimming.

  • A better approach is to use a DC ammeter, for example a Fluke 175, inserted in series with the negative battery cable terminal clamp and the negative battery terminal or a clamp-on DC ammeter, like a Fluke 336 or i410 around the negative battery cable. Starting with the highest scale, determine the current load. If the load is above 75 milliamps (.075 amps) after the initial surge, then start removing fuses or connections to the positive battery post one-at-a-time until the offending electrical component is identified by the parasitic load dropping to within 75 milliamps (.075 amps).

Oct 17, 2015 | Cars & Trucks

1 Answer

no power at all


Inspect/Test/Replace Hope this helps.

An ignition switch supplies voltage to the ignition control module and/or the ignition coil. Often an ignition sytem thas two wires connected to the run terminal of the ignition switch. On is connected to the module. The other is connected to the primary resistor and coil. The start terminal of the switch is also wired to the module.
You can check for voltage using either a 12-volt test light or a digital multimeter (dmm).
To use a test light:
  • Turn the ignition key off and disconnect the wire connector at the module.
  • Disconnect the S terminal of the starter solenoid to prevent the engine from cranking when the ignition is in the run position.
  • Turn the key to the run position and probe the red wire connection to check for voltage.
  • Check for voltage at the battery terminal of the ignition coil using the test light.
  • Next, turn the key to the start position and check for voltage at the white wire connector at the module and the battery terminal of the ignition coil. If voltage is present, the switch and its circuit are okay.
To do the same test using a DMM:
  • Turn the ignition switch to the off position and back-probe, with the meter's positive lead, the power feed wire at the module.
  • Connect the meter's negative to a good ground at the distributor base.
  • Turn the ignition to the run or start position as needed, and measure the voltage.
  • The reading should be at least 90% of battery voltage.

Dec 21, 2012 | 1999 Buick Regal

1 Answer

my 2000 chevy blazer is having battery issues.i have had the battery a year and replaced the altinator a year ago,and something keeps draining the battery.I can't seem to figure this one out


if you have an volt meter capable of reading amperage you can check for a draw fairly easily.

Turn off the vehicle, remove the key, unplug any accessories from the 12 volt (cigarette) outlets, and disable the under hood light if equipped.

Disconnect the negative battery cable from the battery. Install your amp meter in series, one lead on the negative terminal of the battery and one lead on the negative terminal of the battery cable. You should see less than .050 amps. It may take up to 20 minutes for everything to power down so don't worry if you see more right away.

If after 20 minutes it does not drop lower than .050 amps you have a draw. You can start removing fuses from the underhood fuse block one at a time. If the draw goes away than you have just narrowed down the possibilities to that circuit. Post what fuse you pulled and I can help you further.

If none of those fuses cancel the draw remove one of the test leads. Open the drivers front door and remove the courtesy lamp fuse from the instrument panel fuse block located behind the access panel on the end of the left side of the dash. Reinstall test leads and then start removing those fuses one at a time.

Some common draws are aftermarket stereos, glove box lights, visor mirror lights,

Nov 24, 2010 | 2000 Chevrolet Blazer

1 Answer

Electric problem on 2002 Jeep cherokee 6


I had a similar problem, Mine turned out to be a weak cell in the battery. Here is what I did to find it. First, check what postion is the dome light switch in when this problem happens?

Disconect the negitive battery terminal. connect a volt, ohm, amp, meter in series between the negative battery terminal, and the disconected negative battery cable. How much voltage is showing on the meter? open the door does the voltage go up, or does it drop off?
Close the door wait 30, 40 second voltage should start to decrease back down to 0. This is normal the dome light uses a module to control the dome light delay.
If the voltage does not drop down to zero with the door closed after a min. or 2, select the amp setting in your meter, read the amperage draw. This is what drains the battery, the higher the amperage reading the quicker the battery will drain.
With the meter still hooked up remove one fuse at a time, when the amperage drops off you have found the defective circuit.

Apr 15, 2009 | 2002 Jeep Grand Cherokee

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