How To Set Up Multimeter For Parasitic Draw

Measuring Parasitic Draw

All vehicles draw some power from their batteries when the car is shut off. Vehicles with onboard computers have Random Access Memory (RAM). And accessories such as clocks, audio systems (station presets), seats (Automated Drive Positioner, or ADP), remote door openers, and security systems also need power to maintain retention when the ignition is OFF. Each device with retention has a unlike amount load. The ability used as a issue of this continuous energy or cumulative load is chosen parasitic draw. It is usually a very small-scale describe and then the battery doesn't get drained. Parasitic loads can run twenty to 120 milliamps. If in that location is an electric curt in the vehicle or a malfunctioning accessory it could describe more than its normal load causing a large drain on the bombardment.

In order to check for parasitic draw, a Digital Multi-Meter (DMM) that can handle a minimum of one milliamp and upward to x amps is needed to perform a parasitic describe exam.

Vehicle Preparation

ane. Offset prepare the vehicle for the parasitic draw exam by making sure the battery is charged. Weak batteries don't give accurate results when performing a draw exam. In add-on to diagnosing and charging a weak battery (or if you lot installed a new one to supersede a dead i) make certain to verify that the charging arrangement is operating properly.

2. Turn the ignition OFF, then make sure all electric accessories are OFF, too. This includes unplugging anything plugged in a ability socket(south).

3. Disconnect the electrical connector for the Anti-Theft System Hood Switch (if equipped).

four. Close the Hood.

five. Operate the vehicle to simulate client operation. Run the engine, bulldoze the vehicle, stop the engine, release the hood latch, exit and lock the vehicle.

6. Digital Volt Ohm Meter (DVOM) Grooming (refer to the operating instructions provided with meter).

a. Set DVOM to measure DC Amps on the highest scale (commonly 10A).

b. Motion the DVOM red lead to the Amps position in the meter.

Vehicle Training for Measurement

1. Open up the Hood.

2. Wait at least hr to permit all systems to enter sleep fashion. To go a right reading, the vehicle should be left with the doors closed and the ignition OFF for an 60 minutes before beginning the test.

3. Select Ammeter, and then connect the leads.

The most difficult function of making a parasitic depict measurement is establishing a "shunt" connection through your DVOM prior to disconnecting the terminal cable from the negative battery post.

a. Loosen, but Do Not remove the negative battery concluding.

b. Connect the cerise lead to the negative battery cablevision stop.

c. Connect the black atomic number 82 to the negative battery post.

four. Carefully remove the negative battery cable without breaking the shunt connection while removing the last cable from the battery post. Make sure the DVOM leads remain attached to the battery post and cablevision terminate. It's imperative that you keep this connection to avoid sending one of the modules dorsum into an initialization process which boosts current flow. This may not accident the meters fuse, but it will definitely give you an incorrect reading. You will take to look until that process completes and they are ready to go to sleep before y'all tin try again. The Ammeter should then be able to give you an authentic Parasitic Draw (Dark Current) measurement.

Determining the Source of Parasitic Draw

If the ammeter reading exceeds 23 mA, something may be using too much power. If excessive parasitic draw is present information technology will need to exist corrected then the battery does not drain. To determine the source of Parasitic Draw (Dark Current), start by checking for aftermarket accessories. If whatsoever aftermarket accessories are present, remove the power to these accessories, and so retest.

Finally, follow normal diagnostic procedures to identify source of draw. If you have a high reading, you'll need to cheque each component. For example, remove fusible links, fuses, relays, etc., one at a time until the depict is isolated to the offending electric component/system. Open the door, and tape the door switch open circuit then that the system returns to slumber style. Then, remove each fuse 1 at a time to isolate the circuit causing the draw.

The under hood fuses tin be removed without too much difficulty, and without waking upwards the BCM. If you lot can't place an excessive draw by removing the fuses, and the components bank check out fine, yous may have a wiring problem.

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Source: http://www.nissantechnicianinfo.mobi/htmlversions/Winter_2012/Parastic_Draw.html

Posted by: andersonbarives.blogspot.com

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