Troubleshooting

Basic Troubleshooting Procedures

Basic Troubleshooting Procedure

Customer Problem Analysis Check Sheet

Basic Inspection Procedure: Resistance Measurement Conditions of Electronic Parts. Measured resistance may be high or low when the vehicle is hot after starting. Therefore, all resistances should be measured at ambient temperature (20 °C, 68°F), unless otherwise specified.Intermittent Problem Check Procedure. Sometimes the most difficult case in troubleshooting is when the problem symptom occurs but does not repeat during testing. For example, if the problem appears only on a cold vehicle but does not appear on a warmed-up vehicle. In this case, the technician must carefully complete the "Customer Problem Analysis Sheet" and recreate (simulate) the environment and conditions that existed when the vehicle had the problem.

1. 1
   Clear the Diagnostic Trouble Code (DTC).
2. 2
   Inspect the connector and check the terminals for poor contact, loose wires, bent, broken or corroded contacts, then make sure all connectors are always securely fastened.

   

3. 3
   Gently shake the connector and wire harness vertically and horizontally.
4. 4
   Repair or replace the faulty component.
5. 5
   Confirm that the problem is resolved by performing a road test.

● Simulate vibration

a.	Sensors and Actuators: Gently tap the sensors, actuators or relays with a finger.

b.	Connectors and Harness: Gently shake the connector and harness vertically, then horizontally.

● Simulate heat

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

● Simulate water spray

a.	Spray water on the vehicle to simulate a rainy day or high humidity condition.

● Simulate electrical load

a.	Turn on all electrical systems to simulate excessive electrical loads (radio, blower fans, headlights, rear window defogger, etc.).

Connector Inspection Procedure

1. 1
   Connector Handling

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

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

   b.	Listen for a click when connectors lock. This sound indicates they are securely locked.

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

   e.	Check waterproof connector terminals from the connector side. Waterproof connectors cannot be accessed from the wire harness side.

2. 2
   Connector Checkpoints

   a.	With the connector connected: While holding the connector, check the connection condition and locking efficiency.

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

   b.	Check the terminal tightening condition: Insert a spare plug into the socket, then check the tightness of the terminals.

   d.	Gently pull on individual wires to make sure each wire is secured in the terminal.

3. 3
   Connector Terminal Repair Method

   a.	Clean the contact points using compressed air and/or a cloth.

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

4. 4
   Before removing the harness, check the harness position and clamps so that it can be reinstalled correctly.
5. 5
   Check that the wire 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 harness is rotating, moving, or vibrating, or whether it contacts a sharp edge of a part.
8. 8
   Check the connection between the wire harness and any installed part.
9. 9
   If the harness covering is damaged, secure, repair or replace the harness.
10. 10
    Open Circuit Procedures

    • Continuity Check
    • Voltage Check

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

    

11. 11
    Continuity Check MethodSpecification (resistance): 1 Ω or less → Normal circuit; 1 MΩ or more → Open circuit

    a.

    Disconnect connectors (A) and (C), and measure the resistance between connector (A) and (C), as shown in [FIG. 2]. In [FIG. 2], the measured resistance of lines 1 and 2 is higher than 1 MΩ and lower than 1 Ω, respectively. Specifically, an open circuit is line 1 (line 2 is normal). To find the exact breakpoint, check the sub-section of line 1 as described in the following step.

    b.

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

12. 12
    Voltage Check Method

    a.	With each connector still connected, measure the voltage between chassis ground and terminal 1 of each connector (A), (B) and (C), as shown in [FIG. 4]. The measured voltages of each connector are 5 V, 5 V and 0 V, respectively. Therefore, there is an open circuit between connector (C) and (B).

13. 13
    Short to Ground Check Method

    • Continuity Check with Chassis Ground

    If a short to ground occurs (as shown in [FIG. 5]), the fault location can be found by performing Step 2 (continuity check method with ground) as shown below.

    

14. 14
    Continuity Check Method (with Chassis Ground)Specification (resistance): 1 Ω or less → Short to ground; 1 MΩ or more → Normal circuit

    a.

    Disconnect connectors (A) and (C), and measure the resistance between connector (A) and body ground, as shown in [FIG. 6]. In this example, the measured resistance of lines 1 and 2 is less than 1 Ω and more than 1 MΩ, respectively. Specifically, line 1 is shorted to ground (line 2 is normal). To find the exact breakpoint, check the sub-circuit of line 1 as described in the following step.

    b.

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

Wire Harness Inspection Procedure: Electrical Circuit Inspection Procedure ● Check for open circuit ● Check for short circuit ● Voltage drop test. This test checks the voltage drop across a wire, connection, or switch.

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

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

C.	Operate the circuit.

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

Symptom Troubleshooting Table

Main Symptom	Diagnostic Procedure	Also check
Cannot Start (Engine does not crank)	1 Check the battery. (Refer to Engine Electrical System - "Battery") 2 Test the starter. (Refer to Engine Electrical System - "Starter") 3 Inhibitor switch (A/T) or clutch start switch (M/T)
Cannot Start (Incomplete combustion)	1 Check the battery. (Refer to Engine Electrical System - "Battery") 2 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 3 Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System") 4 Troubleshoot the immobilizer system. (Refer to Body Electrical System - "Immobilizer System") (If the immobilizer lamp is flashing)	Trouble Code Low compression Intake air leaks Slipping or broken timing belt Contaminated Fuel
Hard to Start	1 Check the battery. (Refer to Engine Electrical System - "Battery") 2 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 3 Check the ECT sensor and circuit (check DTC) 4 Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System")	Trouble Code Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Poor Idling (Rough, unstable or incorrect idle)	1 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 2 Check the injector. (Refer to Engine Control System - "Injector") 3 Check the long-term fuel trim and short-term fuel trim. (See CUSTOMER DATA FLOW) 4 Check the idle air control circuit (check DTC). 5 Inspect and check the throttle body 6 Check the ECT sensor and circuit (check DTC)	Trouble Code Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Engine Stalls	1 Check the battery. (Refer to Engine Electrical System - "Battery") 2 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 3 Check the idle air control circuit (check DTC). 4 Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System") 5 Check the CKPS circuit (check DTC)	Trouble Code Intake air leaks Contaminated Fuel Weak ignition spark
Poor Driveability (Surging)	1 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 2 Inspect and check the throttle body 3 Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System") 4 Check the ECT sensor and circuit (check DTC) 5 Check the exhaust system for possible clogging. (Refer to Engine Mechanical System - "Exhaust Manifold") 6 Check the long-term fuel trim and short-term fuel trim. (See CUSTOMER DATA FLOW)	Trouble Code Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Knock	1 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 2 Inspect the engine coolant. (Refer to Engine Mechanical System - "Radiator") 3 Inspect the radiator and the cooling system electric fan. (Refer to Engine Mechanical System - "Radiator") 4 Check the spark plugs. (Refer to Engine Electrical System - "Ignition System")	Trouble Code Contaminated Fuel
Poor Fuel Economy	1 Check the customer's driving habits. · Is the A/C on continuously or the defroster mode on? · Is the tire pressure correct? · Is an excessively heavy load being carried? · Is acceleration too strong or too frequent? 2 Inspect the fuel pressure. (Refer to Fuel System - "Fuel Pressure Inspection") 3 Check the injector. (Refer to Engine Control System - "Injector") 4 Check the exhaust system for possible blockage 5 Check the ECT sensor and circuit	Trouble Code Low compression Intake air leaks Contaminated Fuel Weak ignition spark
Hard to Refuel (Overflow during refueling)	1 Inspect the fuel tank hose/tube. · Pinched, kinked or blocked? · Torn filler hose 2 Inspect the fuel tank vapor hose between the EVAP canister and the air filter 3 Check the EVAP canister	Defective fuel filler nozzle at gas station (If this problem occurs at a specific gas station during refueling)