Kia Forte: OBD-II review
1. Overview
The California Air Resources Board (CARB) began regulation of On Board
Diagnostics (OBD) for vehicles sold in California beginning with the 1988 model
year. The first phase, OBD-I, required monitoring of the fuel metering system,
Exhaust Gas Recirculation (EGR) system and additional emission related components.
The Malfunction Indicator Lamp (MIL) was required to light and alert the driver
of the fault and the need for repair of the emission control system. Associated
with the MIL was a fault code or Diagnostic Trouble Code (DTC) idenfying the
specific area of the fault.
The OBD system was proposed by CARB to improve air quality by identifying
vehicle exceeding emission standards. Passage of the Federal Clean Air Act Amendments
in 1990 has also prompted the Environmental Protection Agency (EPA) to develop
On Board Diagnostic requirements. CARB OBD-II regulations were followed until
1999 when the federal regulations were used.
The OBD-II system meets government regulations by monitoring the emission
control system. When a system or component exceeds emission threshold or a component
operates outside tolerance, a DTC will be stored and the MIL illuminated.
The diagnostic executive is a computer program in the Engine Control Module
(ECM) or PowertrainControl Module (PCM) that coordinates the OBD-II self-monitoring
system. This program controls all the monitors and interactions, DTC and MIL
operation, freeze frame data and scan tool interface.
Freeze frame data describes stored engine conditions, such as state of
the engine, state of fuel control, spark, RPM, load and warm status at the point
the first fault is detected. Previously stored conditions will be replaced only
if a fuel or misfire fault is detected. This data is accessible with the scan
tool to assist in repairing the vehicle.
The center of the OBD-II system is a microprocessor called the Engine
Control Module (ECM) or Powertrain Control Module(PCM).
The ECM or PCM receives input from sensors and other electronic components
(switches, relays, and others) based on information received and programmed
into its memory (keep alive random access memory, and others), the ECM or PCM
generates output signals to control various relays, solenoids and actuators.
2. Configuration of hardware and related terms
1) GST (Generic scan tool)
2) MIL (Malfunction indication lamp) - MIL activity by transistor
The Malfunction Indicator Lamp (MIL) is connected between ECM or PCM-terminal
Malfunction Indicator Lamp and battery supply (open collector amplifier).
In most cars, the MIL will be installed in the instrument panel. The lamp
amplifier can not be damaged by a short circuit.
Lamps with a power dissipation much greater than total dissipation of
the MIL and lamp in the tester may cause a fault indication.
▷ At ignition ON and engine revolution (RPM)< MIN. RPM, the MIL is switched
ON for an optical check by the driver.
3) MIL illumination
When the ECM or PCM detects a malfunction related emission during the
first driving cycle, the DTC and engine data are stored in the freeze frame
memory. The MIL is illuminated only when the ECM or PCM detects the same malfunction
related to the DTC in two consecutive driving cycles.
4) MIL elimination
| • |
Misfire and Fuel System Malfunctions:
For misfire or fuel system malfunctions, the MIL may be eliminated
if the same fault does not reoccur during monitoring in three subsequent
sequential driving cycles in which conditions are similar to those under
which the malfunction was first detected.
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| • |
All Other Malfunctions:
For all other faults, the MIL may be extinguished after three
subsequent sequential driving cycles during which the monitoring system
responsible for illuminating the MIL functions without detecting the
malfunction and if no other malfunction has been identified that would
independently illuminate the MIL according to the requirements outlined
above.
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5) Erasing a fault code
The diagnostic system may erase a fault code if the same fault is not
re-registered in at least 40 engine warm-up cycles, and the MIL is not illuminated
for that fault code.
6) Communication Line (CAN)
| • |
Bus Topology : Line (bus) structure
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| • |
Wiring : Twisted pair wire
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| • |
Off Board DLC Cable Length : Max. 5m
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| • |
Data Transfer Rate
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| - |
Diagnostic : 500 kbps
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| - |
Service Mode (Upgrade, Writing VIN) : 500 or 1Mbps)
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7) Driving cycle
A driving cycle consists of engine start up, and engine shut off.
8) Warm-up cycle
A warm-up cycle means sufficient vehicle operation such that the engine
coolant temperature has risen by at least 40 degrees Fahrenheit from engine
starting and reaches a minimum temperature of at least 160 degrees Fahrenheit.
9) DTC format
| • |
Diagnostic Trouble Code (SAE J2012)
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| • |
DTCs used in OBD-II vehicles will begin with a letter and are
followed by four numbers.
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The letter of the beginning of the DTC identifies the function of the
monitored device that has failed. A "P" indicates a powertrain device, "C" indicates
a chassis device. "B" is for body device and "U" indicates a network or data
link code. The first number indicates if the code is generic (common to all
manufacturers) or if it is manufacturer specific. A "0" & "2" indicates generic,
"1" indicates manufacturer-specific. The second number indicates the system
that is affected with a number between 1 and 7.
The following is a list showing what numbers are assigned to each system.
| • |
1 : Fuel and air metering
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| • |
2 : Fuel and air metering(injector circuit malfunction only)
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| • |
3 : Ignition system or misfire
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| • |
4 : Auxiliary emission controls
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| • |
5 : Vehicle speed controls and idle control system
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| • |
6 : Computer output circuits
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| • |
7 : Transmission
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The last two numbers of the DTC indicates the component or section of
the system where the fault is located.
10) Freeze frame data
When a freeze frame event is triggered by an emission related DTC, the
ECM or PCM stores various vehicle information as it existed the moment the fault
ocurred. The DTC number along with the engine data can be useful in aiding a
technician in locating the cause of the fault. Once the data from the 1st driving
cycle DTC ocurrence is stored in the freeze frame memory, it will remain there
even when the fault ocurrs again (2nd driving cycle) and the MIL is illuminated.
| • |
Freeze Frame List
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| 1) |
Calculated Load Value
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| 2) |
Engine RPM
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| 3) |
Fuel Trim
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| 4) |
Fuel Pressure (if available)
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| 5) |
Vehicle Speed (if available)
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| 6) |
Coolant Temperature
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| 7) |
Intake Manifold Pressure (if available)
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| 8) |
Closed-or Open-loop operation
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| 9) |
Fault code
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3. OBD-II Readiness Test
[Kia Motors Drive Cycle]
Kia OBDII Drive Cycle is designed to execute and complete the OBDII monitors.
To complete a specific monitor for repair verification, follow the Drive Cycle
chart below.
Kia OBDII Drive Cycle consists of two modes (Mode 1 and Mode 2) and the
Mode 2 is to perform the catalyst diagnostics on Dephi EMS only.
| - |
Continental, Bosch or Kefico EMS : Mode 1 drive cycle should be
done one time for diagnostics on all systems.
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| - |
Dephi EMS : Mode 2 drive cycle should be done two times in a row
after Mode 1 is carried out one time for diagnostics on all systems
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| • |
Mode 1
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| • |
Mode 2
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| Mode |
No |
Operation |
Speed (mph) |
Duration (s) |
E/Time (s) |
Remarks |
| Mode 1 |
1 |
Engine Start |
0 |
0 |
0 |
ECT @ Start 32~104°F |
| 2 |
Idling (N) |
0 |
30 |
30 |
Neutral Range |
|
| 3 |
Idling (D) |
0 |
270 |
300 |
D Range |
|
| 4 |
Acceleration |
0 → 50 |
15 |
315 |
|
|
| 5 |
Steady Speed |
50 |
230 |
545 |
|
|
| 6 |
Deceleration |
50 → 45 |
5 |
550 |
|
|
| 7 |
Steady Speed |
45 |
5 |
555 |
|
|
| 8 |
Acceleration |
45 → 55 |
5 |
560 |
|
|
| 9 |
Steady Speed |
55 |
5 |
565 |
|
|
| 10 |
Deceleration |
55 → 45 |
5 |
570 |
|
|
| 11 |
Steady Speed |
45 |
5 |
575 |
|
|
| 12 |
Repeat 8 through 11 ten times. |
- |
180 |
755 |
|
|
| 13 |
Acceleration |
45 → 55 |
5 |
760 |
|
|
| 14 |
Steady Speed |
55 |
5 |
765 |
|
|
| 15 |
Deceleration |
55 → 0 |
45 |
810 |
|
|
| 16 |
Idling (D) |
0 |
120 |
930 |
D Range |
|
| 17 |
Idling (N) |
0 |
760 |
1690 |
Neutral Range |
|
| 18 |
Acceleration |
0 → 55 |
15 |
1705 |
|
|
| 19 |
Steady Speed |
55 |
60 |
1765 |
|
|
| 20 |
Deceleration |
55 → 0 |
15 |
1780 |
|
|
| 21 |
Idling (D) |
0 |
60 |
1840 |
D Range |
|
| 22 |
Acceleration |
0 → 55 |
15 |
1855 |
|
|
| 23 |
Steady Speed |
55 |
60 |
1915 |
|
|
| 24 |
Deceleration |
55 → 0 |
15 |
1930 |
|
|
| 25 |
Idling (D) |
0 |
60 |
1990 |
D Range |
|
| 26 |
Acceleration |
0 → 40 |
15 |
2005 |
|
|
| 27 |
Steady Speed |
40 |
15 |
2020 |
|
|
| 28 |
Acceleration |
40 → 50 |
15 |
2035 |
|
|
| 29 |
Steady Speed |
50 |
5 |
2040 |
|
|
| 30 |
Deceleration |
50 → 40 |
15 |
2055 |
|
|
| 31 |
Steady Speed |
40 |
60 |
2115 |
|
|
| 32 |
Repeat 28 through 31 five times. |
- |
380 |
2495 |
|
|
| 33 |
Acceleration |
40 → 50 |
15 |
2510 |
|
|
| 34 |
Steady Speed |
50 |
5 |
2515 |
|
|
| Mode 1 |
35 |
Deceleration |
50 → 0 |
40 |
2555 |
|
| 36 |
Idling (D) |
0 |
25 |
2580 |
D Range |
|
| Mode 2 |
1 |
Engine Start |
0 |
0 |
0 |
|
| 2 |
Idling (N) |
0 |
30 |
30 |
Neutral Range |
|
| 3 |
Idling (D) |
0 |
210 |
240 |
D Range |
|
| 4 |
Acceleration |
0 → 49 |
16 |
256 |
|
|
| 5 |
Deceleration |
49 → 47 |
2 |
258 |
Lift Foot Up : APS = 0 |
|
| 6 |
Steady Speed |
47 |
10 |
268 |
|
|
| 7 |
Acceleration |
47 → 55 |
4 |
272 |
Middle Tip In or Deep Accel |
|
| 8 |
Deceleration |
55 → 52 |
3 |
275 |
Lift Foot Up : APS = 0 |
|
| 9 |
Steady Speed |
52 |
10 |
285 |
|
|
| 10 |
Deceleration |
52 → 45 |
3 |
288 |
Lift Foot Up : APS = 0 |
|
| 11 |
Acceleration |
45 → 47 |
2 |
290 |
|
|
| 12 |
Repeat 6 through 11 twelve times. |
- |
330 |
620 |
|
|
| 13 |
Steady Speed |
47 |
57 |
677 |
|
|
| 14 |
Deceleration |
47 → 0 |
8 |
685 |
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1. Engine Control Module (ECM)
2. Manifold Absolute Pressure Sensor (MAPS)
3. Intake Air Temperature Sensor (IATS)
4. Engine Coolant Temperature Sensor (ECTS)
5. Throttle Positi ...
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