Scan Tool Data Definitions

FUEL TRIM CELL - The 600 V6 engine uses sixteen fuel trim cells. Cell sixteen is the idle mode cell. Throttle position and MAP determine which cell the engine will be in.

LOOP STATUS - "Closed Loop" displayed indicates that the PCM is controlling fuel delivery according to heated oxygen sensor voltage. In "Open Loop," the PCM ignores the heated oxygen sensor voltage and bases the amount of fuel to be delivered on TP sensor, engine coolant, and MAP sensor inputs only. "Closed Loop" operation should begin when the HO2S becomes active and engine coolant temperature exceeds 65°C (149°F) for more than 30 seconds.

FUEL TRIM ENABLE - If the fuel trim enable system is learning (indicated with "YES") the L. T. fuel trim is responding to the S. T. fuel trim. If the fuel trim enable reads "NO" then L. T. fuel trim will not respond to changes in S. T. fuel trim.

MPH km/h - The Vehicle Speed Sensor (VSS) signal is converted into km/h and mph for display.

FUEL EVAP PURGE - A proportional signal used to control canister purge function. 0% indicates the valve is commanded fully closed while 100% indicates that the valve is fully open.

SPARK ADVANCE - This is a display of the spark advance (IC) calculation which the PCM is delivering to the ignition control module. It computes the desired spark advance using data such as engine coolant temperature, RPM, load, vehicle speed, and operating mode.

SPARK RETARD - Indicates the amount of spark advance the PCM is removing from Ignition Control (IC) timing in response to the Knock Sensor (KS) signal. Should read 0° at idle.


KNOCK SIGNAL - Indicates whether or not a knock signal is being detected by the PCM. Should read "NO" at idle. "YES" may be indicated under hard acceleration.

EGR 1/EGR 2/EGR 3 - Any combination of the three EGR solenoids may be opened during engine operation. The Tech 1 can indicate which solenoids are open or when all three are closed, such as at idle. The Tech 1 can also cycle each solenoid open and closed to evaluate their operation.

IDLE AIR CONTROL - Displays the commanded position of the Idle Air Control (IAC) pintle in counts. The Idle Air Control (IAC) valve should respond fairly quickly to changes in engine load to maintain desired idle RPM.


IGNITION CONTROL 24X SIGNAL - This signal is represented in RPM and indicates the 24X crankshaft position sensor is operating and the PCM is receiving it's signal.

IGNITION CONTROL CAM SIGNAL - The ignition control CAM signal provides the PCM with the information to determine when the intake valve on number one cylinder will open. "0" CLOSED, "1" OPENED - The PCM sequences the injectors in cylinder firing order based on the input from the camshaft sensor.


TCC APPLY SOLENOID - Tech 1 displays TCC "OFF" or "ON" as commanded by the PCM.

SYSTEM VOLTAGE - This represents the system voltage measured by the PCM.

FUEL PUMP VOLTS - This parameter indicates how much voltage is applied to the fuel pump motor. This voltage is sensed from a splice located between the fuel pump relay and the pump motor. This voltage should indicate 12 volts when the ignition key is cycled "ON" for 2 seconds, or whenever the 3X crankshaft position sensor is supplying reference pulses.

A/C REQUEST - Represents the state of the A/C request input from the control head.

A/C CLUTCH - Represents the commanded state of the A/C clutch control relay. Clutch should be engaged when "ON" is displayed.

A/C REFRIGERANT PRESSURE - Tech 1 displays high side refrigerant pressure represented by psi and voltage.

FAN 1 - When the PCM is commanding Fan 1 "ON," the Tech I display will switch from "OFF" to "ON."

FAN 2 (IF APPLICABLE) - When the PCM is commanding Fan 2 "ON," the Tech 1 display will switch from "OFF" to "ON."

INJECTOR FAULT The PCM can determine if any of the six injectors are misfiring. "FAULT" will be displayed if this is occurring.

SMCC ENGAGED (IF APPLICABLE) - The PCM monitors the "Cruise Status" circuit and determines whether the Stepper Motor Cruise Control (SMCC) module is actually energized, "YES" or not engaged "NO."

SMCC INHIBITED (IF APPLICABLE) - The PCM retains the ability to disallow Stepper Motor Cruise Control (SMCC) operation if vehicle speed and other specific criteria are not met. If cruise control is being inhibited, the Tech 1 should display "YES." If the PCM senses all criteria has been met for cruise control operation Tech 1 will display "NO" (not inhibited).

LOW OIL LIGHT (IF APPLICABLE) - The PCM monitors the signal from the oil level sensor and turns this telltale "ON" if oil level is below the desirable level. The lamp is energized for about one second after "Key On" (bulb check) the lamp turns "OFF" as long as the PCM is satisfied that the oil level is sufficient.

HOT ENGINE LIGHT (IF APPLICABLE) - Some vehicles are equipped with a "Temp" symbol telltale. This warns the driver of an engine overheating condition. Other vehicles are equipped with a "Check Gauges" lamp which can warn the driver of several other detected conditions including low fuel level, generator output, engine overheating etc. The Tech 1 can energize the "Check Gauges" or "Temp" telltale depending on the particular application, as long as it is a PCM controlled lamp.

SHIFT SOLENOID "A" (SSA) - The PCM monitors the TP sensor and VSS vs. RPM to determine the correct shift points. 1st gear "ON," 2nd gear "OFF," 3rd gear "OFF," and 4th gear "ON."

SHIFT SOLENOID "B" (SSB) - The PCM monitors the TP sensor and VSS vs. RPM to determine the correct shift points. 1st gear "ON," 2nd gear "ON," 3rd gear "OFF," and 4th gear "OFF"

PRNDL - The Tech 1 can determine through 4 inputs from the transaxle range switch what position the gearshift lever is in. These inputs are A, B, C and a parity input.

TRANS RANGE SWITCH - The tech 1 displays the decoded position of the Trans Range Switch PRNDL inputs. If an error combination is seen by the PCM, "INVALID" or an incorrect gear range will be displayed.

2ND GEAR START SWITCH - Some 4T60E transaxles are equipped with a 2nd gear start switch. When this switch displays "ON," shift solenoid "A" is "OFF" while shift solenoid "B" is "ON." This gives the vehicle the ability to start out in second gear.

TCC PWM SOLENOID - This is the relative position of the pulse width modulated (PWM) solenoid that controls TCC apply pressure. This allows TCC to apply evenly and reduce any harsh engagement.

TRANS FLUID TEMP - This signal is received from a 2 wire sensor located in the transaxle fluid stream. The PCM uses this input to determine shift points and TCC engagement points.

TCC BRAKE SWITCH - Tech 1 displays from "Released" to "Applied" when the brake pedal is applied. The switch sends a signal to the PCM to disengage the TCC.

TCC SLIP SPEED - The RPM difference between engine crankshaft speed and torque converter output speed. When TCC mode is "ON," there should be a small amount of slip.

DTC IGNITION COUNTER - Tech 1 displays the number of key cycles after a DTC was stored in PCM memory. The count increases by 1 with each key cycle.

DTC STORED - Tech 1 displays the number of history DTCs stored in PCM memory.

CALIBRATION ID - The calibration identification describes the particular program being used in the PCM. The Tech 1 display number is not the service part number.

TIME FROM START - A measure of how long the engine has been running. When the engine stops, it is reset zero.