Troubleshooting

TROUBLESHOOTING BASICS

BASIC TROUBLESHOOTING GUIDE

CUSTOMER PROBLEM ANALYSIS SHEET

BASIC INSPECTION PROCEDURE

RESISTANCE MEASUREMENT - ELECTRONIC COMPONENTS

Resistance measured at high temperature after engine start-up may be high or low. Therefore, all resistance measurements should be made at room temperature (20 °C, 68°F), unless otherwise specified.

INTERMITTENT PROBLEM INSPECTION PROCEDURE

Sometimes the most difficult part of troubleshooting is when the problem does not occur, but does not reappear during testing. For example, the problem only occurs when the vehicle is cold and not when it is warm. In this case, the technician should carefully complete the "Customer Problem Analysis Sheet" and attempt to recreate (simulate) the environment and conditions in which the problem occurred.

1. 1
   Erase the Diagnostic Trouble Code (DTC).
2. 2
   Check the connector connection and check the terminals for faulty connections, loose wires, deformed, broken or corroded terminals. Then check that the connectors are always connected correctly.

   

3. 3
   Gently shake the connector and wire harness in the vertical and horizontal directions.
4. 4
   Repair or replace the faulty component.
5. 5
   Make sure the problem has disappeared during the road test.

? SIMULATION OF VIBRATION

K.	Sensors and actuators: Lightly vibrate sensors, actuators or relays with your finger.

b.	Connectors and wiring harness: Lightly shake the connector and wiring harness vertically, then horizontally.

? SIMULATION OF HEAT

K.	Heat the components suspected of causing the malfunction with a hair dryer or other heat source.

? SIMULATION OF WATER SPRAY

K.	Spray water on the vehicle to simulate rainy weather or conditions of extreme humidity.

? SIMULATION OF ELECTRICAL LOAD

K.	Activate all electrical systems to simulate a voltage surge (radio, fans, lights, rear window defroster, etc.).

CONNECTOR INSPECTION PROCEDURE

1. 1
   Handling the Connector

   K.	Never pull on the wire harness when disconnecting connectors.

   b.	When disconnecting a connector with a lock, press or pull the lock lever.

   vs.	Listen for a click when connectors are engaged. This sound indicates that they are locked correctly.

   d.	When using a test device to check circuit continuity or to measure voltage, always insert the probe from the wire harness side.

   e.	Make sure the connector terminals are waterproof on the connector side. The waterproof connectors cannot be accessed from the harness side.

2. 2
   Connector Checkpoint

   K.	When the connector is connected: Hold the connector and carefully check the connection and locking.

   b.	When the connector is disconnected: Check for a missing terminal, a crimped terminal, or a broken wire core when lightly pulling the wiring harness. Visually check for rust, contamination, deformation and bending.

   vs.	Check the terminal tightening condition: Insert a spare male terminal into the female terminal, then check the terminal tightening condition.

   d.	Gently pull on each individual wire to make sure that each wire is properly connected to the terminal.

3. 3
   Connector Repair Method

   K.	Clean the contact areas with compressed air and/or a rag.

   b.	If the contact pressure is abnormal, replace the female terminal.

4. 4
   Before removing the wiring harness, check the position of the wiring harness and crimping in order to repair it correctly.
5. 5
   Make sure the wiring harness is not twisted, stretched or loose.
6. 6
   Check that the wire harness is not exposed to excessive temperature.
7. 7
   Check whether the wiring harness rotates, moves or vibrates against a sharp edge of a part.
8. 8
   Check the connection between the wiring harness and all installed components.
9. 9
   If the wire harness sheath is damaged, secure, repair or replace the wire harness.

WIRING HARNESS INSPECTION PROCEDURE - ELECTRICAL CIRCUIT INSPECTION PROCEDURE

? OPEN CIRCUIT CHECK

1. 1
   Open Circuit Procedures

   • Continuity Check
   • VOLTAGE CHECK

   If an open circuit occurs (as shown in [FIG. 1]), it can be detected by Step 2 (continuity check method) or Step 3 (voltage check method), as shown below.

   

2. 2
   Continuity Check MethodSpecification (resistance) 1 Ω or less > Normal circuit 1 MΩ or more > Open circuit

   K.

   Disconnect connectors (A) and (C) and measure the resistance between these two connectors as shown in [Fig. 2]. In [Fig. 2], the resistance measured on lines 1 and 2 is greater than 1 MΩ and less than 1 Ω, respectively. Line 1 is an open circuit (line 2 is normal). To find the exact point of the break, check the sub-circuit of line 1 as described in the following step.

   b.

   Disconnect connector (B) and measure the resistance between connectors (C) and (B1) and connectors (B2) and (A) as shown in [Fig. 3]. In this case, the resistance measured between connectors (C) and (B1) is greater than 1 MΩ, and the open circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).

3. 3
   Voltage Check Method

   K.	For connectors that are still connected, measure the voltage between chassis ground and terminal 1 of connectors (A), (B) and (C) as shown in [Fig. 4]. The measured voltage of each connector is 5 V, 5 V and 0 V, respectively. Therefore, the open circuit is between connectors (C) and (B).

? SHORT CIRCUIT CHECK

1. 1
   Short to Ground Check Method

   • Chassis Ground Continuity Check

   In case of a short to ground [Fig. 5], the fault point can be detected by performing step 2 (chassis ground continuity check method) as shown below.

   

2. 2
   Continuity Check Method (with Chassis Ground)Specification (resistance) 1 Ω or less > Short to ground 1 MΩ or more > Normal circuit

   K.

   Disconnect connectors (A) and (C) and measure the resistance between connector (A) and chassis ground as shown in [Fig. 6]. The resistance measured on lines 1 and 2 in this example is less than 1 Ω and more than 1 MΩ, respectively. Line 1 is short to ground (line 2 is normal circuit). To find the exact point of the break, check the sub-circuit of line 1 as described in the following step.

   b.

   Disconnect connector (B) and measure the resistance between connector (A) and chassis ground, and between (B1) and chassis ground, as shown in [Fig. 7]. The resistance measured between connector (B1) and chassis ground is 1 Ω or less. The short to ground in the circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).

? VOLTAGE DROP TEST

This test checks for voltage drop across a wire or through a connection or switch.

Q.	Connect the positive lead of the voltmeter to the end of the wire closer to the battery (or to the connector or switch side).

B.	Connect the negative jumper lead to the other end of the wire (or the other side of the connector or switch).

vs.	Run the circuit.

D.	The voltmeter shows the voltage difference between two points. A difference or drop of more than 0.1 volt (50 mV in a 5 V circuit) may indicate a problem. Check the circuit for poor or dirty connections.

SYMPTOM TROUBLESHOOTING CHART

MAIN SYMPTOM	DIAGNOSTIC PROCEDURE	ALSO CHECK
Engine Will Not Start (Engine Does Not Crank)	1 Check the battery. (See Engine Electrical System - Battery.) 2 Test the starter. (See Engine Electrical System - Starter.) 3 Has a lock switch (A/T) or clutch start switch (M/T)
Cannot Start (Incomplete combustion)	1 Check the battery. (See Engine Electrical System - Battery.) 2 Check the fuel pressure. (See Fuel System - Fuel Pressure Check.) 3 Check the ignition circuit. (See Engine Electrical System - Ignition System.) 4 Immobilizer diagnosis. (See Body Electrical System - Immobilizer System.) (If the immobilizer indicator is flashing)	diagnostic trouble codes Low compression Intake air leaks Timing belt has slipped or broken Contaminated Fuel
Hard Starting	1 Check the battery. (See Engine Electrical System - Battery.) 2 Check the fuel pressure. (See Fuel System - Fuel Pressure Check.) 3 Check the ECT sensor and circuit (check DTC) 4 Check the ignition circuit. (See Engine Electrical System - Ignition System.)	diagnostic trouble codes Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Poor Idle (Rough, unstable, or incorrect idle speed)	1 Check the fuel pressure. (See Fuel System - Fuel Pressure Check.) 2 Check the injector. (See Engine Control System - Injector.) 3 Check the long-term and short-term fuel trim. (Refer to Customer Data Flow.) 4 Check the idle air control circuit (check DTC). 5 Inspect and clean the throttle body. 6 Check the ECT sensor and circuit (check DTC)	diagnostic trouble codes Low compression Intake air leaks Contaminated Fuel Weak ignition spark
ENGINE STALLS	1 Check the battery. (See Engine Electrical System - Battery.) 2 Check the fuel pressure. (See Fuel System - Fuel Pressure Check.) 3 Check the idle air control circuit (check DTC). 4 Check the ignition circuit. (See Engine Electrical System - Ignition System.) 5 Check the CKPS circuit. (Check the DTC.)	diagnostic trouble codes Intake air leaks Contaminated Fuel Weak ignition spark
Poor Driving (Imbalance)	1 Check the fuel pressure. (See Fuel System - Fuel Pressure Check.) 2 Inspect and clean the throttle body. 3 Check the ignition circuit. (See Engine Electrical System - Ignition System.) 4 Check the ECT sensor and circuit (check DTC) 5 Check whether the exhaust system is clogged. (See Engine Mechanical System - Exhaust Manifold.) 6 Monitor the long-term and short-term fuel trim (see CUSTOMER DATA FLOW).	diagnostic trouble codes Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Knock	1 Check the fuel pressure. (See Fuel System - Fuel Pressure Check.) 2 Check the coolant. (See Engine Mechanical System - Radiator.) 3 Check the radiator and the electric cooling fan of the cooling system. (See Engine Mechanical System - Radiator.) 4 Check the spark plugs. (Refer to Engine Electrical System - "Ignition System".)	diagnostic trouble codes Contaminated Fuel
Poor Fuel Economy	1 Check the customer's driving habits. Is the air conditioner or defroster kept on constantly? Are the tire pressures correct? · Is the vehicle carrying an excessively heavy load? Is acceleration too strong or too frequent? 2 Check the fuel pressure. (See Fuel System - Fuel Pressure Check.) 3 Check the injector. (See Engine Control System - Injector.) 4 Check the exhaust system for blockage. 5 Check the ECT sensor and circuit	diagnostic trouble codes Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Difficult Refueling (Fuel overflow during refueling)	1 Inspect the fuel supply tube/hose. Is it crushed, kinked or clogged? Is the fuel supply hose torn? 2 Check the fuel tank vapor vent hose located between the fuel vapor canister and the air cleaner. 3 Check the fuel vapor canister.	Gasoline filler nozzle malfunction at the fuel station (if this problem occurs at a specific station during refueling).