Road test the vehicle and operate all accessories to check for proper operation.There are many things that can prevent the vehicle from completely going to sleep and passing the parasitic draw test. To begin diagnosis of a parasitic draw, it’s important to properly set up the test. If voltage drop is found, refer to the Power Distribution Schematics to diagnose exactly which circuit of a suspected system is causing the high parasitic drain. Compare the reading to the corresponding fuse in the table. 2) For three-bladed fuses, the center of the fuse is the supply voltage for both sides of the fuse. Once the fuse block feed with the highest draw has been identified, go to that fuse block and check voltage drop across fuses, excluding J-case type fuses, one at a time. Use a DMM set to mV scale to check the voltage drop between the battery positive post and each leg of the battery junction block (if equipped) to determine which fuse block contains the draw. Several tables have been added in SI that list the milliAmps (mA) value across the fuses in a fuse block.
Gm service information down verification#
It features updated information on diagnostic aids, system verification and testing, including a new parasitic draw voltage drop test and a battery draw verification sheet to help with diagnosis.
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If there is an excessive load on the electrical system that is draining the battery after the ignition is turned off, review the Battery Electrical Drain/Parasitic Load Test document under 12V Charging and Starting > Diagnostic Information and Procedures in the Service Information.
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A new voltage drop test in Service Information (SI) can help in determining which component may be causing a parasitic draw. Components most likely to cause a parasitic draw on the 12V battery on GM models include switches, relays, LIN buses and control modules.