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Input Display Procedure

  1. When troubleshooting a malfunction, the ECM, BCM, or IPC input display can be used to determine if switched inputs can be properly interpreted. When one of various input test is selected, the state of that device is displayed as "HI" or "LO".
  2. In general, "HI" and "LO" refer to input terminal voltage for that circuit. The display also indicates if input changed state so that a technician can activate or deactivate any listed device and return to display to see if it changed state. If a change of state occurred, an "X" will appear next to "Hi/Lo" indicator, otherwise a "O" will remain displayed.
  3. The "X" will only appear once per selected input, although "Hi/Lo" indication continues to change as input changes. Some tests are momentary and the "X" can be used as an indication of a change.
ECM INPUT DISPLAY PARAMETERS

Code Display Parameter
EI71 "LO" BRAKE SWITCH
EI72 "HI" THROTTLE SWITCH
EI74 "LO" PARK/NEUTRAL
EI78 "LO" P/S PRESSURE SWITCH
IPC INPUT DISPLAY PARAMETERS

Code Display Parameter
II78 "HI" HEADLAMP SWITCH
II79 "LO" HIGH BEAM SWITCH
II80 "LO" DIMMER SWITCH
II81 "HI" DIMMER PHOTOSENSOR
II82 "LO" TWILIGHT SWITCH