A request for a specific malfunction associated with the operation of the oxygen content in the exhaust gases can only be made after a test drive of at least 10 minutes, if no other malfunction occurs.
The ROM also remembers faults caused by a temporary violation of the integrity of the wiring or contacts. If such malfunctions do not recur within approximately eight engine starts. their codes are automatically erased from memory.
Request for fault codes entered in the ROM. Indication of fault codes. entered into the ROM of the electronic control unit, is carried out using a control lamp located in the instrument cluster (pic. 2-68). When the ignition is turned on, the lamp lights up. After starting the engine, if no serious malfunctions are found in the operation of the engine, the lamp goes out.
When polling the contents of the ROM of the self-diagnosis system, the malfunction indicator lamp should flash.
Indication of fault codes. When interrogating the self-diagnosis ROM, four-digit fault codes are displayed as a sequence of groups of blinks of the malfunction indicator lamp with intervals between groups of blinks lasting 2.5 seconds, during which the indicator lamp is off. Each character of the four-digit code corresponds to the number or group of flashes from 1 to 4. If no faults are found in the system. code 4-4-4-4 is displayed. At the end of the indication of the sequence of codes, the code 0-0-0-0 is displayed. In this case, the control lamp flashes at constant intervals of 2.5 s.
The entry of fault codes into the ROM of the control unit occurs only when the ignition is on.
Four groups of flashes of the requested malfunction code appear after the issuance of a start signal, at which the control lamp lights up, and a pause of 2.5 seconds, during which the control lamp does not light up. After the output of the fourth group of flashes, another pause of 2.5 s follows. The corresponding flashing code is then flagged by means of a start signal until the ignition is switched off or the engine speed exceeds 2500 rpm.
Example:
- the control pump burns for 2.5 s;
- the control lamp goes out for 2.5 s.
The start signal is given:
- the lamp flashes twice;
- the lamp goes out for 2.5 s;
- the lamp flashes three times;
- the lamp goes out for 2.5 s;
- the lamp flashes four times;
- the lamp goes out for 2.5 s;
- the lamp flashes twice;
- the lamp goes out for 2.5 s.
Thus, the code 2-3-4-2 is issued. After that, the cause of the malfunction is determined by the table of fault codes. After eliminating the malfunction, the code of which was entered into the ROM, its code should be erased from the contents of the ROM.
After that, the ROM is polled again for the presence of the next fault.
Fault ROM polling. When polling the fault ROM, the following sequence of operations should be strictly observed:
- Fault ROM Demand:
- elimination of the detected malfunction;
- erasing the code of the eliminated malfunction from the contents of the ROM;
- new fault ROM interrogation.
Thus, the request for the detection of the next fault is possible only after the previous one has been eliminated and its code has been erased.
If no other fault is found, re-interrogate the fault ROM after a test drive for at least 10 minutes.
The fault ROM is interrogated as follows: Check that all wiring connections are secure, that the fault indicator lamp and fuse N918 are working. Start and warm up the engine to normal operating temperature and let it idle. When checking, do not increase the crankshaft speed.
Note. If the engine does not start, before starting the test, turn on the starter for 6 seconds and leave the ignition on.
Slide up the protective cover of the gear lever and connect to 5 with the wire from «weight» red output «1» pads located next to the gear lever (pic. 2-69). On vehicles that do not have such a block, connect with a wire to «weight» yellow-black wire of the ignition coil connector for at least 5 s (pic. 2-70). The system malfunction indicator lamp in the instrument cluster should start flashing.
Count and record the number of flashes in each group. Eliminate the identified problem.
Erase the troubleshooting code. Continue checking until the code 0-0-0-0 appears, indicating the end of the indication of fault codes. The output of the code 4-4-4-4 means that there are no malfunctions in the injection system.
Erase the contents of the fault ROM. Switch off the ignition. Connect wire to «weight» red connector terminal or yellow-black wire of the ignition coil connector. Turn on the ignition. Disconnect wire after 5 s «masses». The previous fault code has been removed from the ROM.
Note. The table of fault codes also contains instructions for their elimination. The last column of the table shows the steps for checking the electrical circuits of the system through the terminals of the computer connector according to the table below «Checking the electrical parameters of the STsV «Mono-Jetronic» through the ECU connector».
Codes 2-3-4-1 and 2-3-4-3 can only be erased by disconnecting the connector of the electronic control unit for at least 30 seconds.
Visitor comments