Scan Tool Data Definitions Part 2

SHRT Term FT Bn1 and Bn2: The scan tool displays percentage. This parameter indicates the average of the short term fuel trim cells. The short term fuel trim cells are rated for the amount of which they are used. For example, the PCM rates an idle cell higher than a wide open cell. If a fueling malfunction occurs in the idle cell and the wide open cell, the idle cell would affect more than then the wide open cell. A negative value significantly below 0 percent indicates that the fuel system is rich and the PCM is reducing the fuel delivery. A positive value significantly more than 0 percent indicates that a lean condition exists and the PCM is compensating by adding fuel. When the average of the cells reach a predetermined high or low, a fuel trim DTC sets.

Short Term FT Bank 1 and Bank 2: The scan tool displays percentage. The short term fuel trim represents a short term correction to fuel delivery by the PCM in response to the amount of time the fuel control oxygen sensor voltage spends above or below the 450 mV threshold. If the oxygen sensor voltage mainly remains less than 450 mV, indicating a lean air/fuel mixture, short term fuel trim increases into the positive range above 0 percent. The PCM adds fuel. If the oxygen sensor voltage stays mainly above the threshold, the short term fuel trim decreases below 0 percent into the negative range. The PCM reduces the fuel delivery in order to compensate for the indicated rich condition. Under certain conditions such as an extended idle and a high ambient temperature, the canister purge may cause the short term fuel trim to read in the negative range during normal operation. The fuel trim values at maximum authority may indicate an excessively rich or lean system.

Spark: The scan tool displays a range of -64 degrees to +64 degrees. The scan tool displays the amount of degrees the PCM commands the spark advance on the IC circuit. The PCM computes the desired spark advance using the following: (1) engine coolant temperature (ECT), (2) engine speed (RPM), (3) load, (4) vehicle speed. The PCM adjusts the timing.

Start Up ECT: The scan tool displays a range of -39 °C to +140 °C (-38 °F to +284 °F). The scan tool displays the engine ECT at the time the engine was started. The PCM uses start-up ECT for certain DTCs.

TCC Brake Pedal Switch: The scan tool displays Applied or Released. This parameter indicates the state of the torque converter clutch/cruise control (TCC/CC) brake switch circuit input. Open indicates 0 voltage input, brake switch open, brake pedal applied. Closed indicates a B+ voltage input, brake switch closed, brake pedal released. When you apply the vehicle brakes, the scan tool displays Applied. The TCC/CC disengages. When you release the vehicle brakes, the scan tool displays Released. This allows the CC to be resumed and the TCC to engage.

TCC Enable Solenoid Command: The scan tool displays ON or OFF. The scan tool displays ON when the electrical system supplies a voltage to the TCC enable solenoid.

TCC PWM Solenoid Command: The scan tool displays ON or OFF. This parameter is the commanded state of the (TCC) PWM solenoid. The scan tool displays ON when the commanded state of the solenoid is ON. The scan tool displays OFF when the solenoid is OFF.

TFP SW: The scan tool displays the transmission gear position.

Torque Delivered Signal: The scan tool displays ft or lbs. Represents the pulse width modulation (PWM) signal which indicates the percent of available torque the engine is delivering to the drive wheels. The electronic brake/traction control module (EBCM) monitors the Traction Control Torque signal to ensure that the powertrain control module (PCM) is responding properly to the Traction Control Desired Torque signal.

Torque Request Signal: The scan tool displays ft or lbs. Represents the pulse width modulation (PWM) signal from the electronic brake and traction control module. The electronic brake/traction control module (EBCM) reduces the traction control desired torque signal pulse width when a drive wheel slippage situation is detected. The powertrain control module (PCM) monitors the traction control desired torque signal and reduces drive wheel slippage as necessary by retarding spark timing, decreasing boost solenoid PWM, or increasing air/fuel ratio. The PCM can also turn OFF up to three fuel injectors if the traction control desired torque signal indicates a large enough amount of drive wheel slippage. A problem with the Traction Control Desired Torque signal should cause DTC P1571 to set.

TP Sensor: The scan tool displays 0-100 percent. The scan tool displays the amount of throttle opening in percentage. The scan tool displays about 0 percent at closed throttle. The scan tool displays about 100 percent at wide open throttle (WOT).

TP Sensor: The scan tool displays 0-5 volts. The scan tool displays the amount of throttle opening in voltage. When the throttle is at a closed throttle the voltage is between 0.4-0.9 volts. When the throttle is at WOT the voltage is above 4.0 volts.

TR Switch: The scan tool displays the transmission gear position.

Transmission OSS: The scan tool displays the transmission output shaft speed in RPM. The output speed sensor (OSS) provides the input signal.

Vehicle Speed Sensor: The scan tool displays km/h and mph. The vehicle speed sensor signal is converted into km/h and mph for display on the scan tool.

VTD Auto Learn Timer: The scan tool displays Active/Inactive. The auto learn timer is the indication if the vehicle theft deterrent (VTD) system is in the learn mode and has not timed out.

VTD Fuel Disable: The scan tool displays Active/Inactive. If the PCM has not received the correct password from the BCM, the PCM disables the fuel system and the scan tool displays Active. The scan tool displays Inactive under normal operating conditions.

VTD Fuel Disable Until Ignition Off: The scan tool displays Yes or No. With the ignition ON and a VTD code present, the scan tool displays Yes.

Warm Ups w/o Emission Faults: The scan tool displays a range of 0-255. This parameter counts the number of warm up cycles without an emission fault present. The counter increments to 255 and rolls back to 0 unless a fault occurs. If a fault occurs, the counter reverts back to 0 until the fault is corrected. Clearing the information with a scan tool or a loss of power to the PCM also resets the counter to 0.

Warm Ups w/o Non - Emission Faults: The scan tool displays a range of 0-255. This parameter counts the number of warm up cycles without a non-emission fault present. The counter increments to 255 and rolls back to 0 unless a fault occurs. If a fault occurs, the counter reverts back to 0 until the fault is corrected. Clearing information with a scan tool or a loss of power to the PCM also resets the counter to 0.