Key-Off Battery Drain Flashcards

What can excessive key-off battery drain lead to?

A run-down battery, even if the battery is in good condition.

What is a common cause of slight battery draw in vehicles?

Some systems need voltage at all times to store information.

What are examples of items that continuously draw a small current when the vehicle is off?

Radio presets and the digital clock.

What is the typical acceptable range for key-off battery drain?

Under 30 to 50 milliamps.

How long can some circuits stay 'awake' after the ignition is off?

Up to eight hours.

What can happen if a glove box or trunk light switch is defective?

It can draw excessive current and drain the battery in days.

What should be used to determine proper key-off drain specifications?

The manufacturer’s suggested specifications.

What is the most effective way to check for key-off battery drain?

Using an ammeter in series with the negative battery cable.

What should be done during testing for key-off battery drain?

Ensure the ignition switch is OFF and all lights are off.

What tool can help identify if an electronic control module refuses to 'go to sleep'?

A capable scan tool.

What is the procedure if there is an excessive drain displayed?

Remove fuses one at a time until the normal reading returns.

What should be noted after pulling a fuse that reduces current draw?

Use a wiring diagram to identify specific circuits associated with that fuse.

What is the alternative approach if the drain isn't found by the fuse method?

Disconnect circuits connected to the battery using a fusible link.

What is a common issue with Electronic Control Modules concerning battery drain?

They fail to power down after the key is turned off.

Why can traditional testing methods be ineffective for finding parasitic drain?

They may reset modules, making faults impossible to detect.

How is voltage drop used to test for current drain?

Measure the voltage drop across the fuses.

What type of reading indicates that a circuit is on when measuring voltage drop?

Any reading other than 0.0 milliamps.

What does current flowing through a fuse indicate?

There will be a measurable voltage drop across the fuse.

What unit should a voltmeter be set to when measuring voltage drop?

Millivolts.

What will a reading across a fuse show if there's excessive draw?

The circuit is drawing current which should be isolated.

What should users refer to locate the faulty circuit after finding a hot fuse?

The Power Distribution diagram.

What is a critical step when isolating circuits to find excessive draw?

Disconnect each circuit one at a time.

What happens when the draw returns to normal during troubleshooting?

You've identified the circuit causing the problem.

What is the purpose of a DMM in checking key-off battery drain?

To read the excessive draw of current through the battery.