Diagnostic Test Procedures

Fig. 5 ECM input display chart:

When troubleshooting a system malfunction, the input display can be used to test the four switch inputs to the ECM.
Following the ECM and BCM trouble code displays, ECM will appear on CCP as outlined previously. With the ECM message displayed on the panel, depress the Hi, then the Lo button. This will allow the technician to bypass ECM data and proceed directly to ECM inputs. Selection of the ``Input'' test type will result in the first available test being displayed. Input status is displayed as ``HI'' or ``LO'' and will be shown as ``0'' until detects that input has cycled from ``HI'' TO ``LO'' or ``LO'' to ``HI.'' When the cycle is complete, the ``0'' will be replaced by an ``X,'' indicating that the input being checked has passed the input test. if the inputs will not cycle, or an intermittent input is suspected, refer to ``ECM Input Display Diagnosis.'' Four characters of the display will contain a test code to identify the selection. The first two characters are letters which identify the system and test type. The last two characters are numerals which identify the test itself (Example: EI71). Depressing the Hi button will display the next largest test number for the selected test type, while depressing the Lo button will display the next smaller test number for the selected test. Depressing the Off button will stop the test selection process and return the display to the next available test type for the selected system (Example: ECM Outputs). Available input displays are shown in Fig. 5.