Battery Electrical Drain/Parasitic Load Test
Battery Electrical Drain/Parasitic Load Test
Tools Required
SA91307 Parasitic Load Tester
Notice: Do not turn the parasitic draw test switch to the OFF position with the engine running. Damage will occur to the vehicle's electrical system.
Notice: The test switch must be in the ON position when removing the fuses in order to maintain continuity in the electrical system. This avoids damaging the digital multimeter due to accidental overloading, such as a door being opened to change a fuse.
Important: The ignition key must be removed from the ignition cylinder before parasitic load testing in order to deactivate the key-minder circuit.
1. Turn the ignition and all accessories OFF and remove key from the ignition switch.
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.
For Vehicles equipped with OnStar� (UE1) with Back Up Battery:
The Back Up Battery is a redundant power supply to allow limited OnStar functionality in the event of a main vehicle battery power disruption to the VCIM (OnStar module). Do not disconnect the main vehicle battery or remove the OnStar fuse with the ignition key in any position other than OFF. Retained accessory power (RAP) should be allowed to time out or be disabled (simply opening the driver door should disable RAP) before disconnecting power. Disconnecting power to the OnStar module in any way while the ignition is On or with RAP activated may cause activation of the OnStar Back-Up Battery (BUB) system and will discharge and permanently damage the back-up battery. Once the Back-Up Battery is activated it will stay on until it has completely discharged. The BUB is not rechargeable and once activated the BUB must be replaced.
2. Disconnect the battery negative cable from the battery negative terminal.
3. Install the male end of the SA9130Z to the battery negative terminal.
Important: The alligator clamp on the parasitic load test device must be connected to the flat pad area on the battery negative cable. Do not connect the alligator clamp to the bolt on the battery negative battery cable.
4. Connect the SA9130Z clamp to battery negative cable.
5. Set the digital multimeter (DMM) to the MILLIVOLT scale.
6. Measure the current across the tester by putting the DMM probes into the 2 terminals of the parasitic load tester. The reading is obtained in volts. This reading is directly converted into milliamperes. The LED indicator on the test device will light if current draw is greater than 1 amp. This may indicate that a vehicle accessory is On.
7. Check and record the current reading.
8. Note the battery reserve capacity.
8.1. Divide the reserve capacity by 4.
8.2. Compare this to the multimeter milliampere reading taken in the previous step.
The parasitic current drain should not exceed this number.
Example: If a battery has a reserve capacity of 100 minutes, the current drain should not exceed 25 mA.
9. Check the charging system if the vehicle has an acceptable amount of current drain. Refer to Charging System Test Initial Inspection and Diagnostic Overview.
Notice: The test switch must be in the ON position when removing the fuses in order to maintain continuity in the electrical system. This avoids damaging the digital multimeter due to accidental overloading, such as a door being opened to change a fuse.
10. When the vehicle has an unacceptable amount of parasitic current drain, remove each fuse one at a time until the current drain falls to an acceptable level. This will indicate which circuit is causing the drain. Refer to Power Distribution Schematics in Wiring Systems to diagnose exactly which part of the suspect circuit is causing the parasitic drain. In some cases a non-fused circuit or component, such as a generator, is the cause of excessive parasitic current drain.
11. Repeat the parasitic current drain test procedure after any repair has been completed to make sure that the parasitic current drain is at an acceptable level.
12. When the cause of the excessive current draw has been located and repaired, remove the SA9130Z.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
13. Connect the negative battery cable.
Tighten
Tighten the negative battery cable bolt to 15 Nm (11 lb ft).
14. Repeat parasitic current drain test procedure after any repair has been completed to make sure that the parasitic current drain is now at an acceptable level.
15. When the cause of the excessive current draw has been located and repaired, remove the parasitic load tester.