Data Displays

DESCRIPTION:

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

1. Depress and release the "LO" button on the CCP. The PCM 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.1.8), depress the "Lo" button on the CCP.

3. When troubleshooting a malfunction, the PCM 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, the parameter range is from -9 to +90.0. The throttle angle displayed is actual indicated angle, not the throttle angle corrected by the PCM adaptive learning routine. A decimal point will appear before the last digit.

P.O.2 The MAP value is displayed in kilopascals (kPa). The parameter range is form 14 to 108.

P.O.3 The computed BARO value is displayed in kilopascals (kPa), the parameter range is from 60 to 102. BARO is calculated from MAP readings taken at Wide Open Throttle (WOT).

P.O.4 The coolant temperature is displayed in degrees Celsius (°C). The parameter display range is -40°C to 151°C.

P.O.5 The manifold air temperature is displayed in degrees Celsius (°C). The parameter display range is -40°C to 151°C.

P.O.6 The spark advance value is displayed in degrees. This value will agree with a timing light on the engine (±2 degrees) if the base timing has been properly adjusted. The parameter display range is 0° to 90°.

P.O.7 The battery voltage is read in volts. A decimal point will appear before the last digit. The parameter display range is 0 to 25.5 volts.

P.O.8 The engine speed is displayed in RPM/10 (120 should be read as 1,200 RPM). The parameter display range is 0 to 637, multiply the parameter by 10 to get rpm.

P.O.9 The vehicle speed is displayed in miles per hour (mph). The parameter display range is 0 to 255 mph.

P.1.2 The injector pulse width is displayed in milliseconds. A decimal point will appear before the last digit. The parameter display range is 0 to 99.6 ms.

P.1.4 The oxygen sensor voltage is displayed in volts. A decimal point will appear before the two digits. The parameter display range is 0 to 1.14 volts.

P.1.6 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.1.8 Fuel Integrator is a record of how long the oxygen sensor voltage has spent in the rich or lean voltage regions. Fuel integrator starts at 128 counts and is reset to 128 counts on acceleration, deceleration and at heavy engine loads. If the fuel system is running too rich for current conditions, the integrator gets smaller to indicate less fuel is needed. If the fuel system is running too lean for current conditions, the integrator gets larger to indicate that more fuel is needed. the parameter display range is 0 (fuel system too rich, a lean command) to 255 (fuel system too lean, a rich command).

P.2.0 Block learn is derived from the fuel integrator value and is used for long-term correction of fuel delivery. A value of 128 counts indicates that fuel delivery is at the proper rate to maintain a 14.7:1 air/fuel ratio and no correction is needed. A value below 128 counts means that the fuel system is too rich and fuel delivery is being reduced (decreased injector pulse width). A value above 128 counts indicates that a lean condition exists and the PCM is compensating by adding fuel (increased injector pulse width). A value between 118 and 138 counts is generally considered normal. Display range is 0 to 255 counts.

P.2.1 The cruise control servo position is displayed in percent (%). A value close to 0% indicates that the cruise control servo is fully extended. A value close to 100% indicates that the cruise servo has retracted to full stroke.

P.2.2 PRNDL switch status. The display will show the state of CKTs 772 and 773 which are the B and C outputs from the PRNDL to the PCM. 0 is the switch closed state and 1 is the switch open state.

P.2.3 PRNDL switch status. The display will show the state of CKTs 771 and 776 which are the A and P outputs from the PRNDL to the PCM. 0 is the switch closed state and 1 is the switch open state.

P.2.4 The ignition cycle counter value is the number of times that the ignition has been cycled to "off" since an PCM trouble code was last detected. After 50 ignition cycles without any malfunction being detected, all stored PCM 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.2.5 The PCM 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 PCM.

When the PCM data display is initiated, the "Data Center" will display a parameter identification (i.e. P.O.1 or P.1.6) 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.