Data Displays

DESCRIPTION:

Code .7.0 must be displayed on the "Data Center" panel before the diagnostics can begin to display the ECM data series. To display the ECM data information, proceed as follows:

1. Depress and release the "LO" button on the CCP. The ECM data series begins as the display switches from code .7.0 to code E.9.0.

2. To advance the display, depress the "Hi" button on the CCP. To return to a lower number parameter or jump directly from E.9.0 to the end of the parameter list (P.1.7), depress the "Lo" button on the CCP.

3. When troubleshooting a malfunction, the ECM data display can be used to compare the vehicle with problems to a vehicle which is functioning properly. Parameter values will vary with environmental and operating conditions. It is therefore necessary to make comparisons with the same type of vehicle under similar conditions.

A brief summary of each parameter is provided below:

P.0.1 The throttle angle is displayed in degrees.

P.O.2 The MAP value is displayed in kilopascals (kPa).

P.O.3 The computed BARO value is displayed in kilopascals (kPa).

P.O.4 The coolant temperature is displayed in degrees celsius (C).

P.O.5 The manifold air temperature is displayed in degrees celsius ("C).

P.O.6 The injector pulse width is displayed in milliseconds. A decimal point will appear before the last digit.

P.O.7 The oxygen sensor voltage is displayed in volts. A decimal point will appear before the two digits.

P.O.8 The spark advance value is displayed in degrees. This value will agree with a timing light on the engine (F2 degrees) if the base timing has been properly adjusted.

P.O.9 The ignition cycle counter value is the number of times that the ignition has been cycled to "off" since an ECM trouble code was last detected. After 50 ignition cycles without any malfunction being detected, all stored ECM codes are cleared and the counter is reset to 0. If a current code is present the counter is reset to 0. If there are not any codes present, the counter increments from 0 to 50 without meaning.

P.1.0 The battery voltage is read in volts. A decimal point will appear before the last digit.

P.1.1 The engine speed is displayed in RPM/10 (120 should be read as 1,200 RPM).

P.1.2 The vehicle speed is displayed in miles per hour (MPH).

P.1.3 The Oxygen Sensor Cross Counts is a measure of oxygen sensor activity. The cross count value is the number of times that the oxygen sensor voltage changes from rich to lean or lean to rich in about a one second period. The crossover counts parameter can be used to detect a "lazy" or slow to swing oxygen sensor when compared to a known good car.

P.1.4 The Fuel Integrator indicates how the ECM is controlling fuel delivery. The integrator is set to a value of 128 when the fuel system is in open loop operation. When the fuel control system goes closed loop, the integrator will follow oxygen sensor rich/lean trends. From 128, the integrator will move higher (add fuel) if the ECM sees a lean signal from the oxygen sensor. The integrator will move lower (subtract fuel) if the ECM sees a rich signal from the oxygen sensor. The integrator will be set to a value of 128 during closed loop operation when an acceleration enrichment, power enrichment, deceleration enleanment, power steering anticipate, A/C anticipate, or P/N to DR anticipate is issued from the ECM.

P.1.5 VCC volts is the voltage reading from the VCC temperature thermister. The parameter display range is 0 volts (hot thermister or circuit shorted) to 5.1 volts (cold thermistor or circuit open).

P.1.6 The ECM PROM I.D. is displayed as a number up to three digits long which can be used to verify that the proper PROM was installed in the ECM.

When the ECM data display is initiated, the "Data Center" will display a parameter identification (i.e. P.O.1 or P.1.7) for one second and then a number will be displayed for nine seconds to indicate the parameter value. The display will continue to repeat this display sequence until the technician decides to move to another parameter.