What does it mean?
SPECIAL NOTES: It should be noted that generic code P0A5B applies to both hybrid-car propulsion systems and conventional charging systems. In both instances, the code has the same basic meaning/definition- “Generator Current Sensor Circuit Low” which refers to the charging current generated by the system being too low, or lower than expected.
Since this code also applies to highly complex hybrid systems, it is as well to bear in mind the official definition (as per SAE ((Society of Automotive Engineers)) document J2012 ) of the word “LOW” as used in this context: – Low Input [shall mean] – “Circuit voltage, frequency, or other characteristic measured at the control module input terminal or pin that is below the normal operating range.” The above definition-within-a-definition represents an important distinction between hybrid and conventional charging systems, because the term “ frequency, or other characteristic” generally does not apply to conventional charging systems to the same degree that it does on hybrid systems, in which a current can be switched between AC and DC, as well as between energy levels several times before it reaches either the traction motor(s) or the battery pack.
Therefore, due to the extreme complexity of hybrid propulsion systems, this guide cannot provide detailed diagnostic and repair information for this code as it applies to hybrid systems. Diagnosing and repair fault codes on hybrid systems requires advanced professional grade diagnostic equipment, as well as above average diagnostic skills in general, and expert-level knowledge of the application in particular.
For this reason, this guide will focus on diagnosing and repairing code P0A5B as it applies to conventional charging systems. As such, the information provided here should NOT be used for diagnosing any electrical issue on any hybrid propulsion system. END OF SPECIAL NOTES.
NOTE #1: With reference to this code as it applies to conventional systems, the word “Generator” is used interchangeably with the word “Alternator”, since the distinction between alternators that generate AC current and generators that generate DC current, is no longer relevant. In automotive parlance today, alternators are almost universally referred to as “generators”.
NOTE #2: “Generator current sensor” in this definition refers to a Hall-effect sensor that monitors and largely controls the current being produced by the generator. OBD II code P0A5B is a generic code that is universally defined as “Generator Current Sensor Circuit Low”, and is set when the PCM (Powertrain Control Module), Body Control Module, or any other relevant controller detects a lower than expected charging voltage or current.
The charging systems of modern vehicles have developed to the point where these systems bear no relation to the charging systems of cars made a mere ten years ago. The multitude of features and electrical consumers fitted to cars today requires that the current fed to each consumer be precisely controlled to extend component life, ensure the stability of all systems, and to maintain proper communication between all control modules.
To accomplish all of the above, modern charging systems are fitted with a current sensor whose function it is to control and adapt the generator’s output to meet varying demands, while keeping the system stable overall.
However, the current sensor is linked to several other controllers and modules that collectively, have the function of maintaining system stability, preserving the battery’s state of charge, as well as the battery’s state of health, while supplying sufficient current to various systems and sub-systems.
Today, a typical charging system consists of a current estimation module, the aforementioned current sensor, as well as a dedicated module that performs diagnostic functions in the charging system in general, but in the current sensor in particular. In terms of operation, the current estimation module determines the estimated amou