Natural Gas Vehicle Module

Natural Gas Vehicle Module:

PURPOSE
The Natural Gas (NG) Vehicle module provides two functions:

- The first function is to operate the fuel injectors and is referred to as the Injector Driver Module (IDM),

- The other function is to send a fuel level indicator signal to drive the fuel gauge and is called the Fuel Indicator Module (FIM).

OPERATION
IDM NG vehicle fuel indicator driver signals are based upon Powertrain Control Module (PCM) injector driver signals and are controlled directly by the corresponding injector drivers in the PCM. The IDM must be used to provide the NG vehicle injectors with the required high current necessary for proper operation. The greater demand of NG vehicle injector current warrants an increased size of the injector driver and increased heat dissipation. Given these conditions, the PCM would not be suitable for placement of these drivers. The IDM closely resembles the Electronic Engine Control IV (EEC-IV) module in appearance.

The IDM injector drivers are capable of controlling the amount of current flow to each NG vehicle fuel injector. Once the injector is open, the 1DM NG vehicle injector driver will reduce current flow sufficient to continue to hold the injector open open. This is done by the IDM in an effort to reduce heat. If the IDM driver does not detect the required peak current to initially open the NG vehicle fuel injector within a specified amount of time, the IDM driver will drop current to injector hold open current.

The FIM is not part of the Powertrain Control subsystem and will not be discussed here.