2.
Inspect connector connection, and check terminal for poor connections, loose wires, bent, broken or corroded pins, and then verify that the connectors are always securely fastened.
Measuring Condition of Electronic Parts' Resistance
The measured resistance at high temperature after vehicle running may be high or low. So all resistance must be measured at ambient temperature (20℃, 68℉), unless stated otherwise.
The resistance measured outside the ambient temperature (20℃, 68℉) is the reference value.
Intermittent Problem Inspection Procedure
Sometimes the most difficult case in troubleshooting is when a problem symptom occurs but does not recur when tested. An example would be if a problem appears only when the vehicle is cold but has not appeared when warm. In this case, the technician should thoroughly make out a "Customer Problem Analysis Sheet" and recreate (simulate) the environment and condition in which the vehicle was having the issue.
Clear Diagnostic Trouble Code (DTC).
Inspect connector connection, and check terminal for poor connections, loose wires, bent, broken or corroded pins, and then verify that the connectors are always securely fastened.
Slightly shake the connector and wiring harness vertically and horizontally.
Repair or replace the component with a problem.
Perform road test to verify that the problem has disappeared.
● Simulating Vibration
Sensors and Actuators
: Slightly vibrate sensors, actuators or relays by finger.
Strong vibration may break sensors, actuators or relays
Connectors and Harness
: Lightly shake the connector and wiring harness vertically and then horizontally.
● Simulating Heat
Heat components suspected of causing the malfunction with a hair dryer or other heat source.
DO NOT heat components to the point where they may be damaged.
DO NOT heat the ECM directly.
● Simulating Water Sprinkling
Sprinkle water onto vehicle to simulate a rainy day or a high humidity condition.
DO NOT sprinkle water directly onto the engine compartment or electronic components.
● Simulating Electrical Load
Turn on all electrical systems to simulate excessive electrical loads (Radios, fans, lights, rear window defogger, etc.).
Handling of Connector
Never pull on the wiring harness when disconnecting connectors.
When removing the connector with a lock, press or pull locking lever.
Listen for a click when locking connectors. This sound indicates that they are securely locked.
When a tester is used to check for continuity, or to measure voltage, always insert tester probe from wire harness side.
Check waterproof connector terminals from the connector side. Waterproof connectors cannot be accessed from harness side.
Use a fine wire to prevent damage to the terminal.
Do not damage the terminal when inserting the tester lead.
Checking Point for Connector
While the connector is connected:
Hold the connector, check connecting condition and locking efficiency.
When the connector is disconnected:
Check missed terminal, crimped terminal or broken core wire by slightly pulling the wire harness.
Visually check for rust, contamination, deformation and bend.
Check terminal tightening condition:
Insert a spare male terminal into a female terminal, and then check terminal tightening conditions.
Lightly pull on each wire to ensure that all wires are secured in the terminal.
Repairing Connector Terminal
Clean the contact points using air gun and/or shop rag.
Never use sand paper when polishing the contact points, otherwise the contact point may be damaged.
In case of abnormal contact pressure, replace the female terminal.
Before removing the wire harness, check the wire harness position and crimping in order to restore it correctly.
Check for twisted, pulled or loose wire harness.
Check for abnormally high temperature of wire harness.
Check if the wire harness is rotating, moving or vibrating against the sharp edge of a part.
Check the connection between the wire harness and any installed part.
If the covering of wire harness is damaged; secure, repair or replace the harness.
● Check Open Circuit
Procedures for Open Circuit
Continuity Check
Voltage Check
If an open circuit occurs (as seen in [FIG. 1]), it can be found by performing Step 2 (Continuity Check Method) or Step 3 (Voltage Check Method) as shown below.
Continuity Check Method
When measuring the resistance, lightly shake the wire harness vertically or horizontally.
Specification (Resistance)
1Ω or less → Normal Circuit
1㏁ or Higher → Open Circuit
Disconnect connectors (A) and (C) and measure resistance between connectors (A) and (C) as shown in [FIG. 2].
In [FIG. 2], the measured resistance is higher than 1㏁ for line 1 and lower than 1Ω for line 2. Specifically, the open circuit is in line 1. (Line 2 is normal.) To find exact breaking point, check sub line of line 1 as described in the following step.
Disconnect the connector (B), and measure the resistance between connectors (C) and (B1) and between (B2) and (A) as shown in [FIG. 3].
In this case, the measured resistance between connectors (C) and (B1) is higher than 1㏁ and the open circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).
Voltage Check Method
With each connector still connected, measure the voltage between the chassis ground and terminal 1 of each of connectors (A), (B) and (C) as shown in [FIG. 4].
The measured voltage of each connector is 5V, 5V and 0V respectively. So the open circuit is between connector (C) and (B).
Test Method for Short to Ground Circuit
Continuity Check with Chassis Ground
If short to ground circuit occurs as shown in [FIG. 5], the broken point can be found by performing Step 2 (Continuity Check Method with Chassis Ground) as shown below.
Continuity Check Method (with Chassis Ground)
Lightly shake the wire harness vertically or horizontally when measuring the resistance.
Specification (Resistance)
1Ω or less → Short to Ground Circuit
1MΩ or Higher → Normal Circuit
Disconnect connectors (A) and (C) and measure the resistance between connector (A) and Chassis Ground as shown in [FIG. 6].
The measured resistance is below 1 Ω for line 1 and higher than 1 MΩ for line 2. Specifically, the short to ground circuit is in line 1. (Line 2 is normal.) To find exact broken point, check the sub line of line 1 as described in the following step.
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 measured resistance between connector (B1) and chassis ground is 1Ω or less. The short to ground circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).
This test checks for voltage drop along a wire, or through a connection orswitch.
Connect the positive lead of a voltmeter to the end of the wire (or to the side of the connector or switch) closest to the battery.
Connect the negative lead to the other end of the wire. (or the other side of the connector or switch)
Operate the circuit.
The voltmeter will show the difference in voltage between the two points. A difference, or drop of more than 0.1 volts (50mV in 5V circuits), may indicate a problem. Check the circuit for loose or dirty connections.
Main symptom | Diagnostic procedure | Also check for |
Unable to start (Engine does not turn over) | 1. Test the battery. (Refer to Engine Electrical System - "Battery") 2. Test the starter. (Refer to Engine Electrical System - "Starter") 3. Clutch start switch (M/T) | |
Unable to start (Incomplete combustion) | 1. Test the battery. (Refer to Engine Electrical System - "Battery") 2. Check the fuel pressure (Refer to Fuel Delivery System - "Repair procedures") 3. Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System") 4. Troubleshoot the immobilizer system. (Refer to Body ElectricalSystem - "Immobilizer System") (In case immobilizer lamp flashes) | ● DTC ● Low compression ● Intake air leaks ● Slipped or broken timing belt ● Contaminated fuel |
Difficult to start | 1. Test the battery. (Refer to Engine Electrical System - "Battery") 2. Check the fuel pressure (Refer to Fuel Delivery System - "Repair procedures") 3. Check the ECT sensor and circuit (Check DTC) 4. Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System") | ● DTC ● Low compression ● Intake air leaks ● Contaminated fuel ● Weak ignition spark |
Poor idling (Rough, unstable or incorrect Idle) | 1. Check the fuel pressure. (Refer to Fuel Delivery System - "Repair procedures") 2. Check the Injector. (Refer to Engine Control System - "Injector") 3. Check the long term fuel trim and short term fuel trim (Refer to CUSTOMER DATASTREAM) 4. Check the idle speed control circuit (Check DTC) 5. Inspect and test the Throttle Body 6. Check the ECT sensor and circuit (Check DTC) | ● DTC ● Low compression ● Intake air leaks ● Contaminated fuel ● Weak ignition spark |
Engine stall | 1. Test the battery. (Refer to Engine Electrical System - "Battery") 2. Check the fuel pressure. (Refer to Fuel Delivery System - "Fuel Pressure Test") 3. Check the idle speed control circuit (Check DTC) 4. Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System") 5. Check the CKPS Circuit (Check DTC) | ● DTC ● Intake air leaks ● Contaminated fuel ● Weak ignition spark |
Poor driving (Surge) | 1. Check the fuel pressure. (Refer to Fuel Delivery System - "Fuel Pressure Test") 2. Inspect and test Throttle Body 3. Check the ignition circuit. (Refer to Engine Electrical System - "Ignition System") 4. Check the ECT Sensor and Circuit (Check DTC) 5. Test the exhaust system for a possible restriction. (Refer to Engine Mechanical System - "Exhaust Manifold") 6. Check the long term fuel trim and short term fuel trim (Refer to CUSTOMER DATASTREAM) | ● DTC ● Low compression ● Intake air leaks ● Contaminated fuel ● Weak ignition spark |
Knocking | 1. Check the fuel pressure. (Refer to Fuel Delivery System - "Repair procedures") 2. Inspect the engine coolant. (Engine Mechanical System - "Radiator") 3. Inspect the radiator and the electric cooling fan. (Engine Mechanical System - "Radiator") 4. Check the spark plugs. (Refer to Engine Electrical System - "Ignition System") | ● DTC ● Contaminated fuel |
Poor fuel economy | 1. Check customer's driving habits · A/C on full time or the defroster mode on? · Are tires at correct pressure? · Is excessively heavy load being carried? · Is acceleration too much, too often? 2. Check the fuel pressure. (Refer to Fuel Delivery System - "Repair procedures") 3. Check the injector. (Refer to Engine Control System - "Injector") 4. Test the exhaust system for a possible restriction 5. Check the ECT sensor and circuit | ● DTC ● Low compression ● Intake air leaks ● Contaminated fuel ● Weak ignition spark |
Hard to refuel (Overflow during refueling) | 1. Inspect the fuel filler hose/pipe · Pinched, kinked or blocked? · Filler hose is torn 2. Inspect the fuel tank vapor vent hose between the EVAP. canister and air filter 3. Check the EVAP. canister | ● Malfunctioning gas station filling nozzle (If this problem occurs at a specific gas station during refueling) |
