VIDEO: Is A Battery A Diagnostic Tool?
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VIDEO: Is A Battery A Diagnostic Tool?

An underperforming battery can cause many diagnostic testing problems. This video is sponsored by The Network Academy.


What do Germans call a dead car battery? A “Nein” volt.

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All jokes aside, we’re talking about how finding the right battery may take a little more diagnostic time, but can make for a happier customer.

With any diagnostic procedure, you first try to rule out the obvious causes of a fault or customer complaint. These items can include fuses, fluid levels and the mechanical operation of the components. But, one item often forgotten is the health of the battery.

The voltage levels in an electrical system can determine how sensors, modules and actuators perform. If the current battery is under performing, it can cause many diagnostic testing problems and codes.

For example, suppose a battery can’t keep the system voltage between 7-9 volts while cranking the engine. In that case, it can generate multiple U-codes indicating a loss of communication between the modules all over the vehicle. Even if the engine starts on some vehicles, the ABS and stability control could go into a fail-safe or inactive mode because the Hi-Speed CAN network crashed during starting due to low voltages.

If you have a scope, you can graph the voltage drop, looking at not only how far the voltage dropped, but the length of time.


On some diagnostic conundrums, you will need a healthy battery to carry out some diagnostic tests. If the battery is failing, you could have inconclusive results if you are trying to bi-directionally control a component line a transmission solenoid or even EVAP valve.

Of course, having the RIGHT battery in the car is the FIRST step.

If the car came standard with an AGM battery, it’s in everyone’s best interest to be sure that’s what it’s replaced with. With two times the cycle life, 20 times the vibration protection and great durability, AGM technology delivers better starting protection than conventional battery designs.

So, before you start wasting valuable diagnostic time, always evaluate the condition – and the composition – of the battery first. If the battery is underperforming, get the customer to authorize replacement. You could resolve many problems before you haul out the diagnostic big guns.

This video is sponsored by The Network Academy.

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