Battery: Testing and Inspection

DIAGNOSIS OF BATTERY VOLTAGE

General Description
A signal below the threshold is not plausible, since the processor of the ECU is not operational if the voltage is less than or equal to 2.5 V. A substitute value is therefore used.

The max. value check is only effective after a delay period from the end-of-start and only with a vehicle speed greater than zero (with a speed signal without faults).

The check of the min. value (fault in the vehicle's electrical power supply system) is only allowed after a delay time from the end-of-start, when the voltage has recovered from the starter activation.

Diagnosis of Battery Voltage






Output Stage Check
The output stages are integrated in manufacturer specific IC's.:
The IC has a binary diagnostic line (e.g. CJ920 2.2 A). The logic circuit within the IC can separate the type of fault to a short circuit to minus, an open line, or a short circuit to plus. The check result will be sent to the ECM via diagnosis line.

Signal tables of output stage check