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State Displays: Notes

  1. This display enables technician to view conditions at the signal level. The 2 types of signals used are analog and digital. Analog signals are monitored at pins corresponding to vehicle harness splices (e.g. fuel pump relay). Digital signals correspond to data transmitted by the system controllers. Both signals are displayed in common units (e.g. temperature), this information is not relative to diagnostic intent.
  2. Use up and down arrow keys on DRB-II to scroll through displays available. When "STATE DISPLAY" is selected, a menu showing systems for which state displays are supported is displayed. If "ENGINE" state display is selected, technician has the option to view either static state displays or "MAX/CURRENT/MIN" value display.
  3. The "STATIC" display shows conditions as they exist at the time the user is viewing the display. The "MIN/CURRENT/MAX" display shows a history of conditions for specific sensor. When this option is selected, maximum, current (static) and minimum value can be displayed for a specific sensor. To reset sensors to a zero value, simply press "ENTER" KEY. This display may be used to isolate intermittent faults.
  4. The following "ENGINE" state displays are available on the DRB-II:
    • Vehicle Program and Calibration Code - Program numbers indicate the ECU is programmed for a specific engine. Calibration code applies to manual or automatic transmission.
    • Battery - Displays battery voltage.
    • H2O - Engine coolant temperature is displayed in degrees Fahrenheit and Celsius.
    • Air - Air temperature is displayed in degrees Fahrenheit and Celsius.
    • TPS - Throttle Position Sensor (TPS) is displayed as "WIDE OPEN", "CLOSED" or "PARTIAL" and percentage of opening from closed throttle to Wide Open Throttle (WOT).
    • A/C Status - If any of the A/C signals are active, an abbreviated display showing A/C state will be dislayed as select "SEL", predict "PRE", clutch "CL" and cut-out "CO". If A/C signals are inactive, "A/C OFF" will be displayed.
    • Relay Status - Displays EGR solenoid, B+ latch relay and fuel pump control relay as on "+" or off "0". When EGR solenoid is off, vacuum is present. When EGR solenoid is on, vacuum is absent.
    • Barometric Pressure Reading - Barometric pressure value can be used to test MAP sensor. A good MAP sensor will read within .60 in. Hg of current barometric pressure at sea level. Subtract .1 in. Hg for every 100 feet above sea level. Current barometric pressure may be obtained from your local weather bureau.
    • RPM - Engine speed is displayed.
    • Exhaust Oxygen Sensor - Displays voltage from O2 sensor and whether fuel system is "RICH" or "LEAN". Displays if system is in "DECEL" condition or in "OPEN LOOP".
    • Pulse Width - Displays the amount of time in milliseconds that the fuel injector is open.
    • Knock - Displays knock sensor noise volume in units from 0-255. If display is more than 250, this will generally indicate a short circuit. Normal readings of a functional knock sensor will be more than 5. A short to ground, open circuit or a non-functioning knock sensor will generally not cause a value above 5 to be displayed.
    • Sync Signal - Displays operation of sync signal on 4.0L engines. Sync Signal is present, DRB-II will display "NO SYNC SIGNAL".
    • ALFACL - The closed loop pulse width correction factor is displayed in units from 0-255. ALFACL represents the correction used to calculate injector pulse width in response to oxygen sensor input. If oxygen sensor reads rich, ALFACL will decrease. If oxygen sensor reads lean, ALFACL will increase.
    • CTAVE - This is average closed throttle value displayed as a percentage of full scale. The closed throttle switch provides a signal to the ECU to indicate closed throttle status.
    • KAM - Keep Alive Memory (KAM) faults are displayed for the O2 sensor, MAP sensor, TPS, air temperature sensor and coolant temperature sensor. Next to sensor display, a pair of numbers is displayed. Each number reflects a period since the ECU has detected a fault. The first number corresponds to a sensed "low" condition failure and the second number corresponds to a sensed "high" condition failure.

    When ECU detects a "low" or "high" condition failure, then number "15" will be stored for the respective sensor. If the engine is started and closed loop is attempted and fault is no longer present, the counter will be decreased by one. If the fault is still present, counter will remain at 15. Values of "0" (zero) are an indication that a "low" or "high" fault condition does not exist for the sensor displayed. Values less than 15 and greater than zero are an indication that the ECU has detected a fault at some time, but fault is not present during the current start cycle (possible intermittent).

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