Injector Driver Module

The Injector Driver Module (IDM) is used in conjunction with the Powertrain Control Module (PCM) to sequentially control power to the fuel injectors on the 7.3L Direct Injection (DI) turbo diesel engine. The PCM processor generates two digital control signals for the IDM: Fuel Delivery Control Signal (FDCS) and Cylinder Identification (CID). The FDCS signal is used by the IDM to control injection timing and injection duration. The CID provides synchronization to the engine's first and fifth injector (firing order). The IDM verifies that FDCS and CID occur at valid timing intervals. The IDM outputs an Electronic Feedback (EF) signal, to the PCM, which is a delayed mimic of the FDCS for verification. Selected diagnostic information is also passed to the PCM via the EF signal in run mode.

The IDM is a high-energy power supply which acts as an energy distributor to provide regulated injector energy and control to the unit fuel injectors, based on FDCS and CID commands from the PCM. All IDM components are solid state; there are no user serviceable parts or adjustments. The IDM internal power supply uses a DC-to-DC converter to boost the Supply Voltage (VBATT) up to 115V DC. This supply is required to overcome the initial impedance of the injectors, ensuring rapid turn on. There are two high side drivers, one for each bank (left and right cylinder bank), and eight low side drivers, one for each injector. One high and one low side must be turned on to energize an injector. Once synchronized with the PCM, the IDM will select the proper low side driver (enable) and control the corresponding high side driver to regulate the current to an injector.

Continuous and on-demand system diagnostic information is provided between the PCM processor and the IDM via the EF signal. During normal operation, the IDM can indicate to the PCM that an injector low side short to ground has been detected, or that the IDM has lost synchronization.

The IDM constantly performs self-diagnostics and also monitors the injector circuits for electrical faults. Any fault codes set are transmitted via the EF signal to the PCM during Key On/Engine Off (KOEO) On-Demand Self Test. If the PCM is unable to obtain diagnostic information from the IDM, DTC 1668 is set.