Trouble Code) diagnostic trouble code. If the trouble is intermittent, the check engine light will go out after restarting but the trouble remains in the ECU memory. If it is a current trouble, the MIL will stay on during vehicle operation. Only when the trouble is repaired and the fault is cleared will the MIL go out and the system will no longer have a fault.
Test mode (trial mode)
The diagnostic function includes a normal mode and a test mode (or test mode).
While normal mode performs normal diagnostics, test mode (or test mode) has a higher sensitivity to detect more detailed failure conditions.
Instant data storage:
The ECU stores in its memory the engine conditions at the time the fault occurs. The conditions that existed at that time can later be retrieved and reviewed through the use of a diagnostic tool.
Safety: The ECU has a safety mode if a fault occurs in some items.
diagnostics. This mode outputs the signals to their specified values to make the vehicle drivable.
Try to activate
During the activation test, a diagnostic device is used to give commands to the ECU to operate the components.
executive.
This activation test determines the integrity of the system or components by monitoring the operation of the actuators, or by reading engine ECU data.
Display DTC (diagnostic trouble code)
Depending on the vehicle model, the test connector may be DLC or DLC3 type. DTCs (Diagnostic Trouble Codes) can be monitored by shorting the terminals of the connector and counting the number of flashes. If no fault occurs, the number of flashes corresponds to normal conditions.
Read fault codes using SST
One method of evaluating DTCs (diagnostic trouble codes) is to use a handheld diagnostic tool. The DTC numbers can be displayed on the screen of this device.
The diagnostic scanner can also be used to display engine conditions or sensor signals (reference values) in addition to displaying DTC numbers.
Figure 7-5 . Read the error code with the device.
- Read DTC (Diagnostic Trouble Code) In the repair manual, the detection item, detection condition and failure area are listed in each
DTC, so please refer to the manual
repair instructions when fixing damage .
b. ECU backup function
If any of the following DTCs are recorded, the ECM enters a standby mode to allow the vehicle to be temporarily run.
DTC Code
Parts | Backup mode operation | Conditions for canceling backup driving mode | |
(1) | (2) | (3) | (4) |
P0031, P0032, P0037 and P0038 | Oxygen sensor with HO 2 drying | The ECM turns off the O2 sensor heater . | Power off |
P0100, P0102 and P0103 | Mass air flow sensor (MAF) | ECM calculates ignition timing based on engine speed and throttle position. | Pass conditions are issued. presently |
P0110, P0112 and P0113 | Air temperature sensor load (IAT) | The ECM considers the IAT to be 20°C (68°F). | Pass conditions are issued. presently |
P0115, P0117 and P0118 | Engine coolant temperature sensor (ECT sensor) | The ECM considers the ECT to be 80°C (176°F). | Pass condition detected |
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If the voltage is out of specification, replace the wire or connector.
If the voltage is within specification, install the front fog light relay and follow step 5.
Step 5 Check the front fog light switch
- Remove the D4 connector of the fog light switch
- Use a multimeter to measure the resistance of the front fog light switch.
Measurement location
Condition
Standard
D4-3 (BFG) -D4-4 (LFG)
Light switchFront Fog OFF
>10kΩ
D4-3 (BFG) -D4-4 (LFG)
Front fog light switchON
<1 Ω
- Standard resistor
D4 connector is located on the combination switch assembly.
If the resistance is out of specification, replace the combination switch (the fog light switch is located in the combination switch).
If the resistance is within specification, follow step 6.
Step 6 Check wiring and connectors (front fog light relay-light selector switch)
- Disconnect connector D4 of the combination switch assembly
- Use a voltmeter to measure the voltage value of jack D4 on the wire side.
Measurement location
Control modecontrol
Standard
D4-3 (BFG) - (-) AQ
TAIL
11 to 14 V
D4 connector for the wiring of the combination switch assembly
If the voltage does not meet the standard, replace the wire or connector.
If the voltage is within standard, there may have been an error in the previous measurements.
Step 7 Check the front fog lights
- Remove the front fog light electrical connector.
- Supply battery voltage to the fog lamp terminals
Jack 8, B9 of front fog lamp on the electrical side
blind first.
Power supply location
Terms and Conditions
Battery positive terminal - Terminal 2Battery negative terminal - Terminal 1
Fog lightsbefore morning
- If the light does not come on, replace the bulb.
If the light is on, re-plug the jack and continue to step 8.
Step 8 Check wiring and connectors (relay and front fog lights)
- Disconnect the B8 and B9 connectors of the front fog lights.
- Use a voltmeter to measure voltage at the following locations:
Measurement location
Switch location
Terms and Conditions
B8-2 - (-) AQ
Electric lock ON TAIL size switchFog switch ON
11 to 14 V
B9-2 - (-) AQ
Electric lock ONTAIL size switch Fog switch ON
11 to 14 V
B8 and B9 connectors on the front fog lamp wiring side
Voltage is not up to standard, repair or replace the jack. If up to standard, there may have been an error in the measurement process.
2.2.4. Procedure for removing, installing and adjusting fog lights 1. Procedure for removing
- Remove the front inner ear pads
Use a screwdriver to remove the 3 screws and remove the front part of the front inner ear liner
-Remove the fog light assembly
+ Disconnect the connector.
+ Use a screwdriver to remove 3 screws to remove the fog light cover
2. Installation sequence
-Rotate the fog lamp bulb in the direction indicated by the arrow as shown in the figure and remove the fog lamp from the fog lamp assembly.
-Rotate the fog light bulb in the direction indicated by the arrow as shown in the figure and install the light into the fog light assembly.
- Use a screwdriver to install the fog light cover
-Install the electrical connector
Attention: Be careful not to damage the plastic thread on the lamp assembly.
- Install the front inner ear pads
Use a screwdriver to install the front inner bumper with 3 screws.
3. Prepare the vehicle to adjust the fog light convergence. Prepare the vehicle:
- Make sure there is no damage or deformation to the vehicle body around the fog lights.
- Add fuel to the fuel tank
- Add oil to standard level.
- Add engine coolant to standard level.
- Inflate the tire to standard pressure.
- Place spare tire, tools and jack in original design position
- Do not leave any load in the luggage compartment.
- Let a person weighing about 75 kg sit in the driver's seat.
4. Prepare to check the fog light convergence
a/ Prepare the vehicle status as follows:
- Place the car in a dark enough place to see the lines. The lines are the dividing line, below which the light from the fog lights can be seen but above which it cannot.
- Place the car perpendicular to the wall.
- Keep a distance of 7.62 m between the center of the fog lamp and the wall.
- Park the car on level ground.
- Press the car down a few times to stabilize the suspension.
Note: A distance of approximately 7.62 m is required between the vehicle (fog lamp center) and the wall to adjust the convergence correctly. If the distance of 7.62 m cannot be achieved, set the correct distance of 3 m to check and adjust the fog lamp convergence. (Since the target area varies with the distance, please follow the instructions as shown in the figure.)
b/ Prepare a piece of thick white paper about 2 m high and 4 m wide to use as a screen.
c/ Draw a vertical line through the center of the screen (line V).
d/ Set the screen as shown in the picture. Note:
- Keep the screen perpendicular to the ground.
- Align the V line on the screen with the center of the vehicle.
e/Draw the reference lines (H, V LH and V RH lines) on the screen as shown in the figure.HINT:
Mark the center of the fog lamp on the screen. If the center mark cannot be seen on the fog lamp, use the center of the fog lamp or the manufacturer's name mark on the fog lamp as the center mark.
H line (fog light height):
Draw a line across the screen so that it passes through the center mark. Line H should be at the same height as the center mark of the fog light bulb.
Line V LH, V RH (center mark position of left fog lamp LH and right fog lamp RH):
Draw two lines so that they intersect line H at the center marks.
5. Check the fog light convergence
a/ Cover the fog lamp or remove the connector of the other side fog lamp to prevent light from the unchecked fog lamp from affecting the fog lamp convergence test.
b/ Start the engine.
c/ Turn on the fog lights and make sure that the dividing line is outside the standard area as shown in the drawing.
6. Adjust the fog light convergence
Use a screwdriver to adjust the fog light to the standard area by turning the toe adjustment screw.
Note: If the screw is adjusted too far, loosen it and then tighten it again, so that the last rotation of the light adjustment screw is clockwise.
3. Self-study questions
1. Describe the operating principle of the lighting system with automatic headlight function
2. Describe the operating principle of the lighting system with the function of rotating headlights when turning
3. Draw diagram and connect lighting system on Hyundai Porter car
4. Draw diagram and connect lighting system on Honda Accord 1992
5. Draw the lighting circuit on a 1993 Toyota Lexus
LESSON 3 MAINTENANCE AND REPAIR OF SIGNAL SYSTEM
I. IMPLEMENTATION GOAL
After completing this lesson, students will be able to:
- Distinguish between types of signals on cars
- Correctly describe common symptoms and suspected areas causing damage.
- Connecting signal circuits ensures technical requirements
- Disassemble, install, check, maintain and repair the signal system to ensure technical requirements.
- Ensure safety in work and industrial hygiene
II. LESSON CONTENT
1. General description
The signal system equipped on cars aims to create signals to notify other vehicles participating in traffic about the vehicle's operating status such as: stopping, parking, braking, reversing, turning...
Signals are used either by light such as headlamps, brake lights, turn signals….. or by sound such as horns, reverse music….
Just like the lighting system. A signal system circuit usually consists of: battery, fuse, wire, relay, electrical load and control switch. Only some switches of the signal system are on the combination switch. The switches of other signals are usually located in different locations such as in the gearbox or brake pedal……
2. Maintenance and repair
2.1. Turn signals and hazard lights
The installation location of the turn signal is shown in Figure 3.1. The turn signal control switch is located in the combination switch under the steering wheel. Turning this switch to the right or left will make the turn signal turn right or left.
The hazard light switch is used when the vehicle has a problem while participating in traffic. When the hazard light switch is turned on, all the turn signals on the vehicle will light up at a certain frequency. The hazard light switch is usually placed separately from the turn signal switch (some old cars integrate the hazard and turn signal switches on the same combination switch cluster).
Figure 3.1 Turn signal switch Figure 3.2 Hazard switch
The part that generates the flashing frequency for the lights is called a turn signal relay. The turn signal relay usually has 3 terminals: B (positive power supply); E (negative power supply); L (providing the turn signal switch to distribute to the
lamp)
2.1.1. Circuit diagram
To generate the frequency for the turn signal, a turn signal relay is used in the turn signal circuit. The current from the turn signal relay will be sent to the turn signal switch assembly to distribute the current to the turn signal lights for the driver's purpose.
Figure 3.3. Schematic diagram of a turn signal circuit without a hazard switch
1. Battery; 2. Electric lock; 3. Turn signal relay; 4. Turn signal switch; 5. Turn signal lamp; 6. Turn signal lamp; 7. Hazard switch
Figure 3.4 Schematic diagram of turn signal circuit with hazard switch
1. Battery; 2. Combination switch cluster; 3. Turn signal;
4. Turn signal light; 5. Turn signal relay
Today's cars no longer use three-pin turn signal relays (B, L, E) but use eight-pin turn signal relays (figure 3.5) (pin number 8 is used for hazard lights).
For this type, the current supplying the turn signal lights is supplied directly from the turn signal relay to the lights.
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P0120, P0121, P0122, P0123, P0220, P0222, P0223, P0604, P0606, P060A, P060D, P060E, P0657, P2102,
P2103, P2111,
Control System Electronic Throttle (ECTS) | The ECM cuts the throttle actuator current and the throttle returns to the 6° position by the return spring. The ECM then controls engine power by controlling fuel injection. (interval injection) and ignition timing according to the position of the table step on the gas. to make the car driveable | The “pass” condition is detected then locked. power off | |||
P0327 and P0328 | Feel the knock | Variable | The ECM sets the maximum ignition timing delay. | Power off | |
P0351, P0352, P0353 and P0354 | Ignition IC | ECM cuts fuel. | Pass conditions | achieve | |
P2120, P2121, P2122, P2123, | Accelerator pedal position sensor (APP) | APP sensor has 2 sensor circuits: Main and Sub | The “pass” condition is | obtain | |
P2125, P2127, | If one of the two circuits is | ||||
P2128 and P2138 | damaged, ECM control | ||||
engine by using | |||||
other circuit | |||||
If both circuits are damaged | |||||
broken, ECM is considered as a leg | |||||
The gas has been released. Result | |||||
is the throttle closed and dynamic | |||||
idling engine | |||||
2.2. FUNCTION, STRUCTURE AND WORKING PRINCIPLE OF SENSOR.
2.2.1. Exhaust gas oxygen sensor
a) Tasks:
The exhaust oxygen sensor is responsible for sensing whether the amount of oxygen in the exhaust gas is darker or lighter than the theoretical ratio to notify the ECU. The oxygen sensor is located in the exhaust pipe.
b) Structure: Figure 7-6 shows the exhaust oxygen sensor, which consists of a part made of a ceramic material. Both the inside and outside of this part are coated with a thin layer of platinum. Outside air is led into the inside of the sensor, while its outside part is exposed to the exhaust gas.
Figure 7-6. Oxygen sensor structure
c) Working principles
When the oxygen concentration on the inner surface of the sensor is greater than that on the outer surface at 400 o C, it generates a voltage. If the gas mixture is lean, there is a lot of oxygen in the exhaust gas so there is a small difference between the oxygen concentration inside and outside the sensor. Therefore, the voltage generated by the sensor is low (nearly 0 volts). Conversely, if the gas mixture is rich, there is almost no oxygen in the exhaust gas. This creates a large difference in the oxygen concentration inside and outside the sensor and the voltage it generates is large (nearly 1 volt). The platinum coating on the ceramic element acts as a catalyst, causing the oxygen in the
The exhaust gas reacts to form CO. This reduces the amount of oxygen and increases the sensitivity of the sensor.
This signal is transmitted to the ECU and the ECU uses this signal to increase or decrease the injection volume to keep the air-fuel mixture ratio close to the theoretical ratio.
2.2.2. Coolant temperature sensor
a) Tasks
The coolant temperature sensor (engine temperature) is responsible for informing the ECU about the engine's specific temperature condition in the form of resistance value. The ECU then calculates the amount of fuel needed to be injected in accordance with the engine's operating mode.
b) Structure and operating principle
Figure 7-7 structure of the coolant temperature sensor consists of a thermistor placed in a metal housing with a threaded barb for mounting into the water bladder. There is a connector on the top.
Figure 7-7. Structure of water temperature sensor
- Operating principle
At low temperatures the fuel evaporates poorly, so a richer mixture is needed, for this reason when the coolant temperature is low the resistance of the thermistor increases and
A high voltage signal is sent to the ECU. Based on this signal, the ECU will increase the amount of fuel injected to increase the load capacity during engine operation when the temperature is low. Conversely, when the coolant temperature is high, a low voltage signal is sent to the ECU so that the ECU reduces the amount of fuel injected. The engine temperature sensor is connected to the ECU as shown in the diagram above. Because the resistor R in the ECU and the thermistor in the engine temperature sensor are connected in series, the signal voltage changes when the resistance value of the thermistor changes.
2.2.3. Intake air temperature sensor
a) Tasks
The intake air temperature sensor is responsible for detecting the temperature of the intake air and reporting it to the ECU.
b) Structure and principle
The construction of the intake air temperature sensor (Figure 7-8) consists of a thermistor mounted in the mass air flow sensor.
The volume and concentration of air change with temperature. Therefore, if the air volume measured by the mass air flow sensor is the same, the amount of fuel injected will change with temperature. For example, the ECU takes the temperature of 20 o c as the standard, when the temperature is higher it will reduce the amount of fuel injected and when the temperature is lower it will increase the amount of fuel injected.
Figure 7-8 Intake air temperature sensor circuit diagram
2.2.4. Engine RPM and DCT sensor
a) Tasks.
The engine's RPM and TDC sensors are responsible for telling the ECU how fast the crankshaft is rotating so that the ECU can control the amount of fuel injected and decide on the early ignition point.
b) Structure and operating principle.
Magnetic sensor type crankshaft rotation sensor (Figure 7-9) introduces the structure of this type.
The location of the magnetic sensor on the engine, consisting of a geared disc mounted on the crankshaft, the grooves on the geared disc generate voltage signals, these signals will indicate the speed and position of the crankshaft. The distance between the sensor head and the geared disc is 1.5 mm, the resistance of the sensor varies from 140 - 200 ohms.
When the crankshaft rotates, the toothed disc passes over the sensor head, causing this unit to generate voltage pulses and send them to the ECU. The ECU counts these pulses to know the crankshaft speed.
Figure 7-9. Crankshaft position sensor location
2.2.5. Intake air pressure sensor
a) Tasks:
The intake air pressure sensor is responsible for sensing the vacuum in the intake manifold to send a signal to the ECU which determines the basic injection volume.