Basic Troubleshooting Guide
Customer Problem Analysis Sheet
Basic Inspection Procedure
Measuring Condition of Electronic Pails' Resistance
The measured resistance at high temperature after vehicle running may be high or low. So all resistance must be measured at ambient temperature (20ºC, 68ºF), unless stated otherwise.
The measured resistance in except for ambient temperature (20ºC, 68ºF) is reference value.
Intermittent Problem Inspection Procedure
Sometimes the most difficult case in troubleshooting is when a problem symptom occurs but does not occur again during testing. 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 which occurred when the vehicle was having the issue.
1. Clear Diagnostic Trouble Code (DTC).
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.
3. Slightly shake the connector and wiring harness vertically and horizontally.
4. Repair or replace the component that has a problem.
5. Verify that the problem has disappear ed with the road test.
Strong vibration may break sensors, actuators or relays.
- DO NOT heat components to the point where they may be damaged.
- DO NOT heat the ECM directly.
DO NOT sprinkle water directly into the engine compartment or electronic components.
Connector Inspection Procedure
1. Handling of Connector
2. Checking Point for Connector
Visually check for rust, contamination, defamation and bend.
3. Repair Method of Connector Terminal
Never use sand paper when polishing the contact points, otherwise the contact point may be damaged.
Wire Harness Inspection Procedure
1. Before removing the wire harness, check the wire harness position and crimping in order to restore it correctly.
2. Check whether the wire harness is twisted, pulled or loosened.
3. Check whether the temperature of the wire harness is abnormally high.
4. Check whether the wire harness is rotating, moving or vibrating against the sharp edge of a part.
5. Check the connection between the wire harness and any installed part.
6. If the covering of wire harness is damaged; secure, repair or replace the harness.
Electrical Circuit Inspection Procedure
1. Procedures for Open Circuit
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.
2. Continuity Check Method
When measuring for resistance, lightly shake the wire harness above and below or from side to side.
1Ω or less →Normal Circuit
1MΩ or Higher → Open Circuit
In [FIG.2.] the measured resistance of line 1 and 2 is higher than 1MΩ and below 1Ω respectively.
Specifically the open circuit is line 1 (Line 2 is normal). To find exact break point, check sub line of line 1 as described in next step.
In tills case the measured resistance between connector (C) and (В 1) is higher than 1MΩ and the open circuit is between terminal 1 of connector (C) and terminal 1 of connector (B1).
3. Voltage Short Method
The measured voltage of each connector is 5V, 5V and 0V respectively. So the open circuit is between connector (C) and (B).
1. Test Method for Short to Ground Circuit
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.
2. Continuity Check Method (with Chassis Ground)
Lightly shake the wire harness above and below, or from side to side when measuring the resistance.
1Ω or less → Short to Ground Circuit
1MΩ or Higher → Normal Circuit
The measured resistance of line 1 and 2 in this example is below 1Ω and higher than 1MΩ respectively.
Specifically the short to ground circuit is line 1 (Line 2 is normal). To find exact broken point, check the sub line of line 1 as described in the following step.
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 or switch.
Symptom Troubleshooting Guide Chart