Performing a Parasitic Draw Test Using the Power Probe Hook

got a customer complaining about a dead battery after the car is parked for a day or two an unwanted parasitic load could be the cause a parasitic load draws continuous current from the battery even when the key is off locating the source of this drain is key to fixing the car hi I'm Jeff Wilson I'm CEO of power probe today we'll show you how to locate an unwanted battery drain by using the power probe hook to monitor total current draw and to capture current surges using power plus mode we'll show you how to supply power to the circuit and maintain the vehicles memory you'll also learn a valuable diagnostic technique on how to isolate the problem circuit without removing fuses it's important to properly prepare the vehicle for testing we need to be certain everything on the car shutdown and the key is out of the ignition electronic modules on today's cars can stay active for up to two hours after the ignition key is turned off all modules must be in sleep mode opening a door activating a remote even removing and reinstalling a fuse can wake up modules be aware of this while performing the test or you may get inaccurate readings if the foot hatch or door need to be open during your test be sure to remove or disable any lamps that come on keep in mind that these could also be your parasitic drains so be sure to check that they are off to perform a parasitic draw test we need to monitor the total current draw from the battery we will use the hook to connect between the negative battery post and the negative battery cable so that all current supplied from the battery to the vehicle is flowing through the tool and being measured by the hooks ammeter keep in mind any time you disconnect the battery the kaepa live memory to the ECM and other modules will be lost this means the radio could lock out by the bility symptoms may and all driver settings could be lost to keep this from happening we'll plug an auto memory saver into a jumper box and then into the vehicles DLC connector this will maintain constant power to the computers keep a live memory now disconnect the negative battery cable then connect the hooks battery clamps to the battery we'll use the 10 gauge extension lead with an alligator clip to extend our reach from the probe jack to the negative battery cable first turn the speaker off now set the adjustable circuit breaker to 65 amps next set the switch mode to latch so we can hold continuous power without holding the switch down and last set the hook to power plus mode now let's complete the connection from the negative post of the battery to the negative battery terminal by pressing the negative power switch notice the green indicator light this shows that the hook is completing the circuit and supplying ground now disconnect the memory saver so that all current will flow through the hook and total amp draw is displayed pressing the hotshot button will reset the min/max capture but be careful not to press any other buttons on the hook or you will turn it off and lose your battery connection and memory it's a general rule not to have more than 50 milliamps of total key off drain but be sure to check your vehicle manufacturer specification for allowable key off current draw if your reading is below 50 milliamps your drain is not excessive however you may have an intermittent condition that does not show up immediately in this situation you have the option of leaving the hook connected to the vehicle for a longer time even overnight to capture a high current draw event your hooks min max capture will store your readings until you return if your amp draw reading is too high we need to do some further testing to locate the specific circuit causing the current drain in the past you could just pull fuses until your amp draw dropped and that would identify the circuit with the drain today's vehicles with can networks should not be disturbed by pulling fuses this could wake up other modules or reset the problem circuit and you could lose the drain you're trying to locate the proper technique to locate an active current draw is by measuring the voltage drop across the fuse to do this take a digital voltmeter and test across each fuse set the voltmeter to its lowest millivolt range then probe both terminals of the fuse at the same time and note any voltage reading if the reading is zero that means there's no current flow in that circuit any reading above zero indicates that there is current flowing through that circuit you can then take that millivolt reading and determine how much current is flowing through that fuse by using one of our fuse conversion charts first select the correct chart for the type of fuse being tested we have four different charts for the most popular fuse types one for mini fuses one for standard ATC fuses one for maxi fuses and one for cartridge fuses you can download a PDF copy of these charts from our website at info probe comm slash fuse charts once you have the correct chart in this case we will use the mini fuse chart flying the column that matches the amp rating of the fuse being tested now find the row with the millivolt number that matches your meter reading and where that row and column intersect is the number that will be your circuits current draw in milliamps one last thing an alternator with a diode problem can also cause an excessive key off drain you can check this by disconnecting the large power feed wire to the alternator and monitor the current draw to see if it drops be sure to plug in the memory saver before you disconnect the hook to reconnect the battery always remember first check the obvious it'll save you time and money if you have any questions please visit power probe com

Channel: Power Probe USA

Views: 187,642

Keywords: Parasitic Draw test, dead battery, battery test, checking a draw, electrical test, draw test, battery problem, the power probe hook, power probe, diagnostic tools, electrical tools

Id: W0FE3fNvJjw

Length: 7min 6sec (426 seconds)

Published: Thu Dec 10 2015