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Troubleshooting Tips

OUTLINE




Main Relay
- If the circuit is open, the engine will not start.
- If the circuit is shorted, the EGI INJ fuse (40 A) will burn out.




PCM Memory Fuse
- If the circuit is open, the PCM memory function will not operate, and diagnostic trouble codes for intermittent malfunctions will not be indicated. Also, the learning control will be canceled, but will not produce any particular symptom.
- If the circuit is shorted, the ROOM fuse (15 A) will burn out.




Ground (Output Devices, Fuel Injector)
- If an output device or a fuel injector has an open ground circuit, no particular symptom will be produced. If a related output device and injectors both have open ground circuits, the engine will not start.

Ground (System, Analogue)
- An open circuit will not produce any symptom.




Data Link Connector 1
- If the circuit is shorted, the opening amount of the idle air control valve will not change, causing hard starting and rough idle. The ignition timing will be fixed, causing lack of power and poor acceleration.
- If the circuit is shorted, the coolant fan operates whenever the throttle valve is opened (Ignition switch ON).




Data Link Connector 2
- If circuit is open or short, the NGS indicates "LINK COMMUNICATION ERROR".

INPUT DEVICES




Mass Air Flow Sensor
- If the Vs terminal of the mass air flow sensor has a short circuit, diagnostic trouble code No.P0100 will be output, and the throttle position sensor and closed throttle position switch signal will be used to adjust the basic injection amount as to the following three modes.
1) Closed throttle position switch ON
2) Small throttle angle
3) Large throttle angle




Throttle Position Sensor
- If the VREF terminal has an open circuit or the TVO terminal has an open or short circuit, diagnostic trouble code No.PO12O is output.
- If the VREF terminal has a short circuit, the engine will not start.
- If the ground terminal has an open circuit, diagnostic trouble code No.P0120 is output.
- In the above conditions, the PCM uses a throttle valve fully-open program.
- If the throttle position sensor is not properly adjusted or the throttle position sensor system fails, poor acceleration or shift shock will result.




Intake Air Temperature Sensor
- If the temperature sensor or circuit has an open or short, diagnostic trouble code No.P0110 is output, and the PCM uses a preprogrammed intake-air temperature of 2O°C (68°F).
- If the intake air temperature sensor system fails, no particular symptom will be noticed.

Closed Throttle Position Switch (In Throttle Position Sensor)
- If the position switch or circuit has on open or short, diagnostic trouble code No.P0510 is output.
- If the circuit is open, rough idle or engine stalling may appear because of inoperative IAC control. If the circuit is shorted, fuel will be cut when the accelerator pedal is pressed, causing hunting.




Heated Oxygen Sensor
- If sensor signal "lean" for approximately 2 minutes in feedback zone, diagnostic trouble code No. P0154 (left bank sensor) and/or P0134 (right bank sensor) is output.
- If the heated oxygen sensor signal remain unchanged for approximately 40 seconds in feedback zone, diagnostic trouble codes No.P0150 (left bank sensor) and/or P0130 (right bank sensor) is output.
- In the above conditions, no feedback control will be present and no symptom will be noticed.







Crankshaft Position Sensor (NE Signal), Camshaft Position Sensor (SGC Signal)
- If the NE signal circuit has an open or short, diagnostic trouble code No.P0335 is output.
- If the SGC signal circuit has an open or short, diagnostic trouble code No.P1345 is output.

Starter Signal
- A lack of starter signal input will cause hard starting.




Power Steering Pressure Switch
- An open circuit can cause a momentary drop in engine speed when steering at idle or low-speed driving.




A/C Signal
- If the circuit is open, the air conditioner will not operate.
- If the circuit is shorted, the air conditioner will constantly operate when the blower is ON.




Engine Coolant Temperature Sensor
- If the temperature sensor or circuit has an open or short, diagnostic trouble code No.P0115 is output, and the PCM uses a preprogrammed temperature value of 40°C (104°F).
- A malfunction in the engine coolant temperature sensor system may cause rough idle, engine stalling, or hard starting.




Blower Signal
- If the circuit has an open, the idle speed may drop when in the high position.




Stoplight Signal
- An open or short circuit will produce no symptom.




Inhibitor Signal
- If the circuit is open, the idle speed will be slightly low in park/neutral position.
- If the circuit is shorted, the idle speed will be slightly high in R, D, S, and L ranges.




Torque Reduction Request Signal
- If the circuit is open or short, diagnostic trouble code No.P1627 is output.
- If a malfunction occurs in the torque reduction request signal, the traction control (TCS) is inhibited and TCS does not operate.




Knock Sensor
- If the knock sensor or circuit has an open or short, diagnostic trouble code No. P0325 is output.
- In the above conditions, ignition timing is retarded.




EGR Valve Position Sensor
- If the EGR valve position sensor or circuit has an open or short, diagnostic trouble code No.P1402 is output.
In the above conditions, the EGR valve will be fully closed.




EGR Boost Sensor
- If the EGR boost sensor or circuit has an open or short, diagnostic trouble code No.R1195 is output.
- An open or short circuit will produce no symptom.




Vehicle Speed Sensor
- If the vehicle speed sensor or circuit has an open or short, diagnostic trouble code No.PO5OO is output.
- An open or short circuit will produce no symptom.




Headlight Switch
- An open or short circuit can cause a low idle speed when the switch is ON.
- A short circuit can cause a slightly high idle speed.

OUTPUT DEVICES

Fuel Injector
- If the circuit is open, the fuel injector will not operate, causing rough idle and misfiring.
- If the circuit is shorted, the fuel injector will inject fuel constantly, will not start or hard start.

IGT Signal (Ignition Control Module)
- If no IGT signals are input to the ignition control module because of an open or short circuit, the engine will not start.

Idle Air Control Valve
- If the solenoid valve or circuit has an open or short, diagnostic trouble code No.P0505 is output.
- If the circuit is open, the idle air control valve will be fully closed, causing rough idle, engine stalling, and acceleration hesitation when cold.
- If the circuit is shorted, the idle air control valve will be fully opened and the idle speed will be increased, causing hunting.

Fuel Pump Relay
- If the circuit is open, the engine will not start.
- If the circuit is shorted, the fuel pump will operate whenever the ignition switch is ON.

Purge Solenoid Valve
- If the solenoid valve or circuit has an open or short, diagnostic trouble code No.P0443 is output.
- If the circuit is open, no symptom will be noticed.
- If the circuit is shorted, the engine stalls at low speed.
- A short circuit may cause an improper air/fuel ratio, causing rough idle and hard starting.




VRIS Solenoid Valve No.1
- If the solenoid valve or circuit has an open or short, diagnostic trouble code No.P1521 is output.
- If the circuit is open, the solenoid valve will stay OFF and the shutter valves will stay closed, causing a poor acceleration or lack of power.
- If the circuit is shorted, the solenoid valve will stay ON and the shutter valves will stay open, causing a poor acceleration or lack of power.




VRIS Solenoid Valve No.2
- If the solenoid valve or circuit has an open or short, Diagnostic trouble code No.P1522 is output.
- If the circuit is open, the solenoid valve will stay OFF and the shutter valves will stay closed, causing a poor acceleration or lack of power.
- If the circuit is shorted, the solenoid valve will stay ON and the shutter valves will stay open, causing a poor acceleration or lack of power.




A/C Signal
- If the circuit is open, the air conditioner will not operate.
- If the circuit is shorted, the air conditioner will constantly operate when the ignition switch is ON.




Torque Reduction Inhibit Signal
- If the circuit open or short, Diagnostic trouble code No.P1627 is output.
- If the circuit is open or shorted, the traction control will not operate.




EGR Solenoid Valve (Vent)
- If the circuit is open or shorted, no symptom will be noticed.




EGR Solenoid Valve (Vacuum)
- If the circuit is shorted, causing rough idle, engine stall.




PRC Solenoid Valve
- If the circuit is shorted, no symptom will be noticed.
- If the circuit is open, the engine will be hard to start when hot.




Condenser Fan Relay No.1
- If the circuit is shorted, the condenser fan and cooling fan will always operate while the ignition switch is ON.
- If the circuit is open, the condenser fan will not operate.




Condenser Fan Relay No.2 and Cooling Fan Relay
- If the circuit is shorted, the cooling fan will always operate while the ignition switch is ON. If the circuit is open, the cooling fan will not operate.

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