Connecting a multimeter to the connectors of the engine control unit using an auxiliary splitter
001 - ECM connectors; 003 - Digital multimeter; 050 - 126-pin splitter; 108 - Test cable; N3/10 - Engine control unit (ME-SFI); A-F - Connectors; II1/63 - Splitter connectors; III63/126 - Splitter connectors
When disconnecting the connectors on the ECM, the center connector is installed last (D).
Important: The red marked connector is not required at this time as the ECM does not have a corresponding feature.
The OBD system includes several diagnostic devices that monitor individual parameters of the toxicity reduction systems and fix the detected failures in the on-board processor memory in the form of individual fault codes. The system also checks sensors and actuators, controls vehicle maintenance cycles, provides the ability to store even short-term failures during operation and clear the memory block.
All models described in this manual are equipped with an on-board diagnostic system (OBD II). The main element of the system is the onboard processor, often called the electronic control module (ECM), or a power unit operation control module (RSM). The PCM is the brain of the engine management system. The initial data is fed to the module from various information sensors and other electronic components (switches, relays, etc.). Based on the analysis of the data coming from the information sensors, and in accordance with the basic parameters stored in the processor's memory, the PCM generates commands for the operation of various control relays and actuators, thereby adjusting the operating parameters of the engine, and ensuring maximum efficiency of its output with minimal fuel consumption. The OBD-II processor memory data is read using a special scanner connected to the 16-pin diagnostic connector for reading the database (DLC), located inside the car.
Note. In principle, reading the fault codes stored in the memory of the self-diagnosis system is possible, on some models, using a lamp «Check engine» or using the auxiliary LED, as well as by the codes displayed on the automatic HF display.
Information about diagnostic tools
Checking the correct functioning of the components of the injection systems and reducing the toxicity of exhaust gases is carried out using a universal digital meter (multimeter). The use of a digital meter is preferred for several reasons. Firstly, it is quite difficult for analog devices to (sometimes impossible), to determine the result of the indication with an accuracy of hundredths and thousandths, while when examining circuits that include electronic components, such accuracy is of particular importance. The second, no less important, reason is the fact that the internal circuit of a digital multimeter has a fairly high impedance (the internal resistance of the device is 10 MΩ). Since the voltmeter is connected in parallel to the circuit under test, the measurement accuracy is higher, the smaller the current will pass through the device itself. This factor is not significant when measuring relatively high voltage values (9 ÷ 12 V), however, it becomes decisive in the diagnosis of elements that produce low-voltage signals, such as, for example, an l-probe, where it is a matter of measuring fractions of a volt.
Parallel monitoring of signal parameters, resistances and voltages in all control circuits is possible using a splitter connected in series to the engine control unit connector. At the same time, with the engine turned off, running or while the car is moving, the parameters of the signals at the splitter terminals are measured, from which a conclusion is made about possible defects.
To diagnose electronic systems of the engine, automatic transmission, ABS, SRS and others, special diagnostic scanners or testers with a specific cartridge can be used (if provided), universal cable and connector. In addition, for this purpose, you can use an expensive specialized automotive diagnostic computer, specially designed for the complete diagnosis of most systems of modern cars (e.g. ADC2000 from Launch HiTech). Also, for this purpose, you can use scanners and specialized diagnostic analyzers, such as FDS 2000, Bosch FSA 560 (www.bosch.de), KTS 500 (0 684 400 500) or a regular personal computer with a special adapter, cable (e.g. kit 1 687 001 439) and installed by the program browser OBD II.
Some scanners, in addition to the usual diagnostic operations, allow, when connected to a personal computer, to print circuit diagrams of electrical equipment stored in the memory of the control unit (if laid down), program the anti-theft system, observe the signals in the car circuits in real time.
Diagnostics of electronic control systems for engine, injection and ignition, automatic air conditioning and ABS/ASR/ETS/ESP
Location of the 16-pin diagnostic connector, if installed
16-pin OBD II diagnostic connector (on USA models)
Output No | Purpose |
1 | — |
2 | — |
3 | TNA Signal (petrol); TD (diesel) |
4 | Housing connection, class. 31 |
5 | Housing - signal terminal, cl. 31 |
6 | CAN data bus high (salon) |
7 | Engine electronics (ME) |
8 | Nutrition, cl. 87 |
9 | Anti-slip system (ETS/ESP) |
10 | — |
11 | Transmission control unit (ETC) |
12 | activity module (AAM – All Activity Module) |
13 | Security systems |
14 | CAN data bus. Low level (salon) |
15 | IC dashboard |
16 | Plus batteries through the fuse. Under voltage in any position of the ignition switch, cl. thirty |
38-pin diagnostic connector for flashing codes (if installed)
Connect the wires according to the diagram. The wire shown with a broken line is connected to a specific terminal for diagnosing a specific system (refer to the contact assignment list):
- to terminal 4 for diagnostics of the injection system;
- to pin 8 for diagnosing the main unit;
- to pin 17 for diagnosing the ignition system;
- to pin 19 to check the diagnostic unit.
Pin assignment of the 38-pin diagnostic connector
1 | Weight, circuit 31 (W12, W15, electronic ground) | |
2 | Voltage, circuit 87 | |
3 | Voltage, circuit 30 | |
4 | EDS | Electronic injection system (diesel engines) |
DFI | Fuel injection with electronic distribution (diesel engines) | |
IFI | Sequential electronic fuel injection (diesel models) | |
HFM-SFI | HFM Sequential Port Injection/Ignition System (engines 104) | |
LH-SFI | LH sequential port injection system (engines 104, 119, 120 [right]) | |
ME-SFI | ME sequential port injection system (engines 119, 120 [right]) | |
5 | LH-SFI | LH sequential port injection system (motors 120 [left]) |
ME-SFI | ME sequential port injection system (motors 120 [left]) | |
6 | ABS | Anti-lock brake system |
ETS | Electronic traction control | |
ASR | Acceleration slip adjustment | |
ESP | Electronic Stabilization Program | |
7 | EA | Electronic acceleration |
CC/ISC | Speed control / idle speed control system. | |
8 | VM | base module. |
BAS | Emergency brake booster. | |
9 | ASD | Automatic differential lock. |
10 | ETC | Electronic transmission control. |
11 | ADS | Adaptive cushioning system. |
12 | SPS | Speed-sensitive power steering system. |
13 | TNA Signal (petrol models), LH-SFI engines. | |
TN signal (petrol models), HFM motors (ME) -SFI. | ||
14 | Signal, duty cycle information, engines 119, 120 LH-SFI (rights.). | |
15 | Signal, duty cycle information, 120 LH-SFI motors (a lion.). | |
IC | Instrument combination. | |
16 | A/C | Air conditioning system. |
17 | DI | Distributor ignition system, 104, 119 and 120 engines (rights.) |
TD signal (temporary separation) (diesel models) | ||
TN signal, LH-SFI motors. | ||
18 | DI | Distributor ignition system, LH-SFI engines. |
19 | DM | Diagnostic module. |
20 | PSE | Pneumatic equipment. |
21 | CF | Comfort. |
23 | ATA | Anti-theft alarm. |
24-27 | Not used. | |
28 | PTS | Parktronic system. |
29 | Not used. | |
30 | AB | Airbags/Belt Pretensioners ETR (SRS) |
31 | RCL | Remote control of a single lock. |
32-33 | Not used. | |
34 | CNS | Communication and navigation system. |
35-38 | Not used |
Reading and deleting flash codes
Reading codes is done using a simple circuit of a pushbutton switch and an LED. Depending on the type of diagnostic connector and the system being diagnosed, the connection is made as shown in the illustrations.
1. Connect the circuit according to the illustration.
2. Turn on the ignition.
3. Press and hold the switch button for 2-4 seconds. and let her go. After 2 seconds, the LED will give a code, the value of which is equal to the number of flashes. Flash duration 0.5 sec, interval 1 sec. Identify the code by decryption. To read the next code, press the button again. To erase this code, press the button and hold it for 6-8 seconds. In addition, on some models, erasing codes in memory is possible by disconnecting the negative terminal of the battery.
4. Turn off the ignition and disconnect the circuit to check.
Diagnostics of the electronic system of the automatic air conditioner (HF)
Diagnostic codes, in addition to a special scanner, can be read from the display of the KV control unit. Fault codes are stored even when the battery is disconnected.
Reading codes
- Turn on the ignition;
- Move the temperature selection knobs to the HI left and LO right positions;
- Within 20 seconds after moving the handles, simultaneously press and hold the REST and EC buttons for 5 seconds;
- The RECIRCULATION key LED will flash and the display will show OFF;
- Press the right AUTO button for more than 1 sec. If there are no faults in the memory, E will appear on the left side of the display and FF on the right. Otherwise, Ebl is displayed on the left side, and a fault code is displayed on the right (refer to the list of CV codes below);
- To display the next fault code, press the AUTO button;
- To erase the codes after reading them completely, press the right and left AUTO buttons for more than 2 seconds. The left side of the display shows d, the right side shows FF;
- Pressing the right AUTO button restores erased codes (compare with the codes recorded earlier);
- After deleting the codes, E is displayed on the left side of the display, FF on the right;
- Set the temperature selection knob to the normal position;
- Switch off the ignition.