Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2009TAHOE BASE, 4.8 CREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 536 (BATTERY, CHARGING SYSTEM AND STARTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESBATTERY ELECTRICAL DRAIN/PARASITIC LOAD TESTCIRCUIT/SYSTEM VERIFICATION
2009 Chevrolet Tahoe Base, 4.8 C
Circuit/System Verification
2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Verification
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, 2012 Chevrolet Suburban, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
- Most vehicle systems will go to sleep within 30 min but it can take up to 2 h before all systems power down allowing the parasitic draw test to pass. An occasional increase in the parasitic draw is normal as long as it returns within 1 s.
- Closing the door latches/ajar switch while leaving the doors open is recommended, this allows the vehicle systems to perform in a "doors closed" mode while allowing vehicle interior access that may be needed to complete the diagnostic steps.
- Locking doors will arm the vehicle content theft deterrent system if equipped. Failure to arm the system may cause a theft system fault to not be present during testing.
- There are many things that can prevent the vehicle from completely going to sleep and passing the parasitic draw test. Make sure all the conditions listed below are met before performing the parasitic current draw test.
- Ignition OFF
- Key out of the ignition switch - when not equipped with keyless access and start
- Retained Accessory Power OFF - open and close the driver door after ignition OFF
- Scan tool not communicating with a vehicle control module - in some cases it may need to be disconnected from the DLC
- All access doors closed
- Headlamps OFF - auto headlamps disabled
- Any delay lighting OFF
- If equipped with an under hood lamp disable it
- HVAC after blow OFF
- Any accessory that can work with ignition OFF inactive or OFF
- Wait up to 2 min or longer, after all other listed conditions are met
Using an Inductive Pickup Probe
- Connect an inductive pickup probe to the negative battery cable that can read down to 1 mA.
- Ignition OFF, as the vehicle systems shut down test for less than 30 mA of parasitic current drain.
- If greater than the specified range, refer to Circuit/System Testing.
Using the EL 38758 Parasitic Draw Test Switch
WARNING:
Refer to Battery Disconnect Warning .
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.