Spooky goings on in the workshop can dramatically increase service times, risking workshop efficiency and reputation

By making sure that a vehicle battery is tested when it first enters the workshop, and supported during any diagnostic procedures, workshops can avoid frustrating and misleading ‘ghost-faults’, says CTEK Regional Sales Manager, Paul Oddy.
A ghost fault or ghost code is in short, a fault that your diagnostic tool detects for one component, that has actually arisen from another.
For example, when a vehicle arrives for service or to investigate a fault, you immediately connect a diagnostic tool, to identify potential fault or error codes. As part of this procedure, the memory on the vehicle’s Electronic Control Unit (ECU) is scanned, to see if there are any issues to address. Or in the case of a vehicle service – you need to reset the service indicator to tell the vehicle that it has been in for service.
Whilst this procedure is being undertaken, it is crucial that the voltage across the vehicle system is correct. Voltage requirements vary from manufacturer to manufacturer and indeed from model to model, so CTEK says it is good process to check this.
If this diagnostic procedure is undertaken when the battery has low voltage, and isn’t supported, an error code or fault will be reported by the diagnostic tool. And that’s because in the quest to protect against the battery failing, the vehicle Canbus system, the main communication channel between all vehicle control modules, will start to shut down all the systems it doesn´t need like the radio, start/stop function, air conditioning etc.
Error codes may be reported for non-functioning systems, and if you don´t know that low battery voltage is the cause of the fault, you will start looking for, and trying to repair a fault that is not really there – hence the expression “ghost fault” – and it will remain a fault until you have taken care of the low voltage issue.
To protect against this, CTEK recommends two important steps as soon as the vehicle enters the workshop:

  1. Test the battery: using something like the PRO Battery Tester from CTEK will help you to identify if battery voltage is low.
  2. Hook the vehicle up to a battery support unit, in supply mode before undertaking any diagnostic work. Many battery support units, such as the CTEK MXTS40, PRO60 and PRO120, enable you to specify the required voltage, so that potentially time-consuming ghost faults are not reported.

CTEK says around one in three commercial vehicles entering the workshop have a battery that needs attention – so it is quite likely the battery will need support. It says that using a smart battery charger and support unit, like the MXTS40, PRO60 or PRO120, means that as well as supporting the battery, it will charge it too – protecting against the battery voltage dropping even lower that it was when it arrived in the workshop.

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