Battery-Related Driveability Issues Diagnostics

Diagnostic Dilemmas: Battery-Related Driveability Issues

Any experienced automotive trainer will tell you that the automotive starter battery is the foundation of a vehicle electronics system. Of course, most of us nod our heads in agreement and then proceed to diagnose a driveability problem without first testing the battery’s condition! Unfortunately, short-cut procedures don’t work on the really tough no-code engine driveability complaints. As we’ll discover in the following article, low cranking voltages can create no-code driveability issues that may disappear without a trace until the next cold-engine start-up.

Battery Voltage
Many technicians assume that because the engine seems to crank at a normal speed, the vehicle’s starter battery is in good condition. Of course, time and technology has changed the underpinnings of that assumption. Electronic fuel injection and the permanent magnet, reduction-gear starter, for example, has reduced cranking time and cranking amperage so much that bad batteries often go undetected far longer than they should.

The key diagnostic issue, of course, is the cranking voltage that the battery supplies to the vehicle’s electronic systems during cranking. Cranking voltage has become extremely important because at least 10 volts are required to power the PCM and activate systems like the primary ignition, fuel pump and fuel pump relay. When cranking voltages drop to nine cranking volts, it is my experience that engine fuel trim and transmission adaptives are affected to the point that the driver may complain of flooding or poor shift quality. Later in this story, we’ll look at some case studies that illustrate different starting and driveability complaints caused by low cranking voltage.

Battery Ratings
Modern automotive starter batteries are rated in cold-cranking amperes (CCA), cranking amperes and reserve capacity. CCA is the number of cranking amps that a battery can supply at 0

You May Also Like

Snap-on Continues to Offer Free Weekly Product Training Sessions

The online training and question and answer sessions are free of charge.

Snap-on national training manager Keith Wray will continue to hold weekly new product training sessions throughout the year that give professional technicians the opportunity to learn more about Snap-on Fast-Track Intelligent Diagnostics tools such as the ZEUS, TRITON and APOLLO series. 

The online training and question and answer sessions are free of charge and are conducted as follows:

Air Ride Diagnostics: Reservoirs and Compressors

The secret to diagnosing air ride problems is knowing what criteria the system uses to regulate the compressor/reservoir and having the right tool.

Mazda SkyActiv Engine Service Tips

These engines have been reliable, but there are four pattern failures you might see.

Honda Indirect TPMS Systems

Honda indirect TPMS systems do not have air pressure sensors inside the tires.

Honda Oil System Inspection

The leading cause of low oil pressure-related complaints with Honda vehicles is the oil level.

Other Posts

AMSOIL Introduces New OE 0W-40 100% Synthetic Motor Oil

The new OE 0W-40 is primarily for newer RAM HD trucks equipped with the 6.4-liter Hemi engine.

UniClutch Launches Clutch System in the United States

From Australian manufacturer Clutch Industries, UniClutch is a clutch system that delivers uncompromised performance.

Automotive Hall of Fame Announces Class of 2024 Inductees

Six honorees whose efforts helped shape the automotive and mobility marketplace will be recognized.

Castrol Turns 125, Debuts New Market Strategy

As part of the new strategy, Castrol will explore opportunities in battery thermal management, digital and service solutions and data center immersion cooling.