Scan Tool Testing and Procedures
DESCRIPTIONAs the data values given below are standard values estimated on the basis of values obtained from the normally operating vehicles by using a scan tool, use them as reference values. Even when the vehicle is in good condition, there may be cases where the checked value does not fall within each specified data range. Therefore, judgment as abnormal should not be made by checking with these data alone. Also, conditions in the below table that can be checked by the scan tool are those detected by ECM and output from ECM as commands and there may be cases where the engine or actuator is not operating (in the condition) as indicated by the scan tool. Be sure to use the timing light to check the ignition timing.
SCAN TOOL DATA
NOTE:
- With the OBD-II generic scan tool, only star marked data in the below table can be read.
- Asterisk (*) marked data are applicable to vehicles equipped with a tank pressure control solenoid vacuum valve only.
- When checking the data with the engine running at idle or racing, be sure to shift M/T gear to the "Park" position and pull the parking brake fully. Also, if nothing or "no load" is indicated, turn off A/C, all electric loads, P/S, and all the other necessary switches.
SCAN TOOL DATA DEFINITIONS:
FUEL SYSTEM (FUEL SYSTEM STATUS)
Air/fuel ratio feedback loop status displayed as either open or closed loop. Open indicates that ECM ignores feedback from the exhaust oxygen sensor. Closed indicates final injection duration is corrected for oxygen sensor feedback.
CALC LOAD (CALCULATED LOAD VALUE, %)
Engine load displayed as a percentage of maximum possible load. Value is calculated mathematically using the formula: MAP/Barometric pressure x Engine speed/Engine speed at max output x 100%
COOLANT TEMP (ENGINE COOLANT TEMPERATURE, °C, °F)
It is detected by engine coolant temp. sensor
SHORT FT (SHORT TERM FUEL TRIM, %)
Short term fuel trim value represents short term corrections to the air/fuel mixture computation. A value of 0 indicates no correction, a value greater than 0 means an enrichment correction, and a value less than 0 implies an lean correction.
LONG FT (LONG TERM FUEL TRIM, %)
Long term fuel trim Value represents long term corrections to the air/fuel mixture computation. A value of 0 indicates no correction, a value greater than 0 means an enrichment correction, and a value less than 0 implies an lean correction.
MANI ABS PRESS (INTAKE MANIFOLD ABSOLUTE PRESSURE, kPa, in/hg)
It is detected by manifold absolute pressure sensor and used (among other things) to compute engine load.
ENGINE SPEED (RPM)
It is computed by reference pulses from the Camshaft Position Sensor.
VEHICLE SPEED (KM/H, MPH)
It is computed based on pulse signals from vehicle speed sensor in combination meter.
IGN ADVANCE (IGNITION TIMING ADVANCE FOR NO.1 CYLINDER, )
Ignition timing of NO.1 cylinder is commanded by ECM. The actual ignition timing should be checked by using the timing light.
INTAKE AIR TEMP (°C, °F)
It is detected by intake air temp. sensor and used to correct the amount of air passing into the intake manifold as air density varies with temperature.
MAF (Mass Air Flow Rate, gm/s, lb/min)
It represents total mass of air entering intake manifold which is computed based on signals from MAP sensor, IAT sensor, TP sensor, etc.
THROTTLE POS (ABSOLUTE THROTTLE POSITION, %)
When throttle position sensor is fully closed position, throttle opening is indicated as 0 % and 100 % full open position.
OXYGEN SENSOR S1 (HEATED OXYGEN SENSOR-1, V)
It indicates output voltage of H02S-1 installed on exhaust manifold (pre-catalyst).
OXYGEN SENSOR S2 (HEATED OXYGEN SENSOR-2, V)
It indicates output voltage of HO2S-2 installed on exhaust pipe (post-catalyst). It is used to detect catalyst deterioration.
DESIRED IDLE (DESIRED IDLE SPEED, RPM)
The Desired Idle Speed is an ECM internal parameter which indicates the ECM requested idle. If the engine is not running, this number is not valid.
TP SENSOR VOLT (THROTTLE POSITION SENSOR OUTPUT VOLTAGE, V)
The Throttle Position Sensor reading provides throttle valve opening information in the form of voltage.
INJ PULSE WIDTH (FUEL INJECTION PULSE WIDTH, msec.)
This parameter indicates time of the injector drive (valve opening) pulse which is output from ECM (but injector drive time of NO.1 cylinder for multiport fuel injection).
ISC DUTY (IDLE SPEED CONTROL DUTY, %)
This parameter indicates opening of the throttle valve in terms of percentage to opening controllable by the ISC actuator.
TOTAL FUEL TRIM (%)
The value of Total Fuel Trim is obtained by putting values of short Term Fuel Trim and Long Term Fuel Trim together This value indicates how much correction is necessary to keep the air/fuel mixture stoichiometrical.
BATTERY VOLTAGE (V)
This parameter indicates battery positive voltage inputted from main relay to ECM.
EVAP PURGE DUTY (EVAP PURGE FLOW DUTY, %)
This parameter indicates valve ON (valve open) time rate within a certain set cycle of EVAP canister purge valve which controls the amount of EVAP purge. 0% means that the purge valve is completely closed while 100% is a fully open valve.
FUEL TANK PRESS (FUEL TANK PRESSURE, mmHg)
This parameter indicates the pressure in the fuel tank expressed with respect to the barometric pressure. When it is equal to the barometric pressure, it is indicated as 0 mmHg.
CTP SWITCH (CLOSED THROTTLE POSITION SWITCH, ON/OFF)
This parameter will read on when ISC actuator plunger contacts with throttle lever, or OFF when it is apart from throttle lever.
FUEL CUT (ON/OFF)
ON : Fuel being cut (output signal to injector is stopped)
OFF: Fuel not being cut
RADIATOR FAN (RADIATOR FAN CONTROL RELAY, ON/OFF)
ON : Command for radiator fan control relay operation being output.
OFF: Command for relay operation not being output.
ELECTRIC LOAD (ON/OFF)
ON : Headlight, small light, heater fan or rear window defogger ON signal inputted.
OFF: Above electric loads all turned OFF.
AIR CONDITIONING (ON/OFF)
ON : Command for A/C operation being output from ECM to A/C amplifier.
OFF: Command for operation not being output.
EGR SOL VALVE (EGR SOLENOID VACUUM VALVE, ON/OFF)
ON : ON command being output to EGR solenoid vacuum valve.
OFF: ON command not being output.
EGR SOL VAL (Chk) (EGR SOLENOID VACUUM VALVE FOR SYSTEM CHECK, ON/OFF)
ON : ON command being output to EGR solenoid vacuum valve for system check.
OFF: ON command not being output.
CANIST AIR VALVE (EVAP CANISTER AIR VALVE, ON/OFF)
ON : ON command being output to EVAP canister air valve.
OFF: ON command not being output.
TANK PRES VALVE (FUEL TANK PRESSURE CONTROL SOLENOID VACUUM VALVE, ON/OFF)
ON : ON command being output to tank pressure control solenoid vacuum valve.
OFF: ON command not being output.
FUEL TANK LEVEL (%)
This parameter indicates approximate fuel level in the fuel tank. As the detectable range of the fuel level sensor is set as 0 to 100%, however, with some models whose fuel tank capacity is smaller, the indicated fuel level may be only 70% even when the fuel tank is full.
TRANS RANGE -P-, -R-, -N-, -D-, -2- or -L- (TRANSMISSION RANGE SENSOR, P R, N, D, 2 or L ON/OFF)
ON : It is indicated the switch ON in the transmission range sensor.
OFF: It is indicated the switch OFF in it.
SHIFT SOL A-CONT (SHIFT SOLENOID-A, ON/OFF)
ON : ON command being output to shift solenoid-A.
OFF: ON command not being output.
SHIFT SOL B-CONT (SHIFT SOLENOID-B, ON/OFF)
ON : ON command being output to shift solenoid-B.
OFF: ON command not being output.
SHIFT SOL A-MONI (SHIFT SOLENOID-A, ON/OFF)
The monitor result of the shift solenoid-A circuit is displayed.
ON : Electricity being passed to shift solenoid-A or circuit open.
OFF: Electricity not being passed or circuit short.
SHIFT SOL B-MONI (SHIFT SOLENOID-B, ON/OFF)
The monitor result of the shift solenoid-B circuit is displayed.
ON : Electricity being passed to shift solenoid-B or circuit open.
OFF: Electricity not being passed or circuit short.
THROT POS LEVEL (THROTTLE POSITION LEVEL FOR A/T, "0", "1", "2", "3", "4", "5", "6" or "7")
This parameter indicates which level (zone) the throttle valve opening is in. The throttle opening is divided into 8 levels (zones) from "0" (about idle position) to "7" (about full open) and signals are assigned to each opening level (zone). ECM control the automatic gear change of the automatic transmission by using these signals according to the signal from the TP sensor.