Diesel On-Board Diagnostics (OBD) Monitors

Diesel On Board Diagnostics (OBD) Monitors

This section provides a general description of each OBD monitor. In these descriptions, the monitor strategy, hardware, testing requirements, and methods are presented together to provide an overall understanding of each monitor operation.

Each illustration depicts the PCM as the main focus with the primary inputs and outputs for each monitor. The numbers to the left of the PCM represent the inputs used by each of the monitor strategies to enable or activate the monitor. The components and subsystems to the right of the PCM represent the hardware and signals used while carrying out the tests and the systems being tested. The comprehensive component monitor (CCM) illustration has numerous components and signals involved and is shown generically. When referring to the illustrations, match the numbers to the corresponding numbers in the monitor descriptions for a better comprehension of the monitor and associated DTCs.

These monitor descriptions are intended as general information only.

Deviations From Standard Gasoline Implementation of OBD

1. Readiness (all monitors complete) is based on diagnostics for the following 6.0L diesel engine systems:
- Comprehensive component monitor (CCM)
- Misfire detection monitor
- EGR monitor

The glow plug monitor is part of the comprehensive component monitor.

Readiness is based on every OBD (component) having run sufficiently to have found a fault without regard to whether or not a fault exists.

2. The OBD drive cycle provided in Section 2 is used to clear a P1000 code. The diesel system differs substantially from the gasoline system.
3. The command to clear DTCs ONLY clears P1000 if all drive cycle testing has been satisfied. All other detected DTCs are cleared with a CLEAR code command from the diagnostic tool if the fault that caused the DTC is no longer present.