Parasitic Current Drain Testing With An Ammeter

1. Turn the ignition and all accessories Off.
2. Disconnect the cable from the negative battery terminal.
3. Follow the manufacturers instructions for the multimeter or ampmeter being used. This could involve plugging the leads into different locations on a multimeter and changing the scale to read amperage. On some testers you should start on the 10 AMP scale setting, and after verifying that the current drain is less than two milliamps, set the scale to 200 milliamps or 20 milliamps.
4. Connect ampmeter between the negative cable and the negative battery terminal so that it is in series. Read the parasitic current drain from the battery.
5. To find the source of the excessive load, start removing the fuses in a systematic way. When the voltage drops across the tester, the circuit or circuits protected by that fuse is the source of the current drain. Repair the circuit and perform the parasitic load test again to verify the repair. Battery Electrical Drain/Parasitic Load Test

Typical Parasitic Loads
Typical parasitic load for this vehicle is 10-15 mA. If vehicle does not have one of the following components, then subtract parasitic load of component for typical parasitic load of vehicle (10-15 mA) to determine parasitic load range for vehicle being tested.

^ ABS 1.0 mA
^ BCM 1.0-3.5 mA
^ CD Changer (refer to Note below) 3.0 mA
^ ECM 0-1.0 mA
^ Generator 0-1.0 mA
^ HVAC Delayed Blower Control 1.0 mA
^ I/P Cluster w/Security Flashing "Security" Telltale 1.2 mA
^ On-Star (refer to Note below) 0-1.0 mA
^ Radio 2.8-4.3 mA
^ TCM 0-10 mA

NOTE:
^ During CD changer initialization, parasitic current draw will fluctuate between 3 mA - 1 A. The initialization period lasts up to a maximum of 90 seconds. After initialization, the CD changer parasitic current draw will stabilize at approximately 3 mA.
^ On-Star module will have a parasitic load of 125 mA 10 minutes after ignition is turned off. This load will drop to 0 and then return to 125 mA every 10 minutes.

If the CD changer door is open and the light is illuminated, the parasitic current draw will be approximately 65 mA. The light will remain on for two minutes. After the light goes out, the CD changer parasitic current draw will stabilize at approximately 3 mA.

Typical Undesired Parasitic Loads
^ Park lamps On
^ Headlamps On
^ Dome lamp On
^ Map lights On
^ Cargo lamp On
^ Radio On
^ Cigar lighter On
^ Fog lamp switch On (will draw current even with ignition switch Off)