Charging Indicator

The charging indicator gives an indication to the vehicle operator when the electrical system voltage is too low or too high. This indicator is controlled by a transistor on the IPC circuit board based upon IPC programming and electronic messages received by the IPC from the Powertrain Control Module (PCM) over the CAN data bus.

The charging indicator LED is completely controlled by the IPC logic circuit, and that logic will only allow this indicator to operate when the IPC receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided a path to ground by the IPC transistor. Each time the ignition switch is turned to the ON position the charging indicator is illuminated by the IPC for about three seconds as a bulb test. The IPC will turn ON the charging indicator for the following reasons:

• Voltage Low Message  - Each time the IPC receives an electronic system voltage  message from the PCM indicating the voltage is low (less than about 11.5 volts is a charge fail condition), the charging indicator will be illuminated. The indicator remains illuminated until the IPC receives a message from the PCM indicating the voltage is normal (greater than about 12.0 volts, but less than 16.0 volts), or until the ignition switch is turned to the OFF position, whichever occurs first.
• Voltage High Message  - Each time the IPC receives an electronic system voltage  message from the PCM indicating the voltage is high (greater than about 16.0 volts), the charging indicator will be illuminated. The indicator remains illuminated until the IPC receives a message from the PCM indicating the voltage is normal (less than about 15.5 volts, but greater than 11.5 volts), or until the ignition switch is turned to the OFF position, whichever occurs first.

The PCM continually monitors the electrical system voltage to control the generator output. The PCM then sends the proper messages to the IPC. If the IPC turns ON the charging indicator due to a charge fail or voltage high condition, it may indicate that the charging system requires service.