With Integrated Fault-Diagnosis System (Flash Codes)
Fault Diagnosis, Stored Faults
Important: Read all through the starting sequence before turning the ignition switch to the ON position.
1 Ground pin 1 in the three-pin test socket on the left-hand side of the engine bay. Connect the cable with switch, part No.83 93 886 (-M1992), or cable 83 94 504 to the ISAT scan tool's black diagnostic socket (M1989-92).
M1993: Use only the ISAT scan tool's black diagnostic socket.
2 Use the "CHECK ENGINE" lamp (MIL) for reading the fault codes.
Turn the ignition switch to the ON position.
The "CHECK ENGINE" lamp (MIL) will light up.
3 Set the switch to the "ON" position (grounding pin 16 of the control module).
M1990-: Wait until "CHECK OIL LEVEL" and "CHECK RADIATOR LEVEL" have gone out. The "CHECK ENGINE" lamp (MIL) will go out.
4 Now carefully observe the "CHECK ENGINE" lamp (MIL). After about 2.5 seconds it will flash briefly ,which means that the first fault code has been activated.
Set the switch to the "OFF" position immediately after the lamp flash.
5 The first fault code (of three possible) is now activated and immediately after the activation signal it will be signaled in the form of short flashes of the "CHECK ENGINE" lamp (MIL).
Important: The fault code begins and ends with a long flash of the "CHECK ENGINE" lamp (MIL). These long flashes have nothing to do with the fault code itself but serve only as signals to indicate the beginning and end of the code.
Fault code
The entire sequence from beginning to end will then look like the diagrammatic representation in the illustration.
Accordingly, the fault code is 12112. The fault code table shows that this means that the fuel-air mixture at idle speed is incorrect.
With the switch in the "OFF" position the next fault code, if any, in the memory of the control module will not be activated. Instead, fault code 12112 will be flashed again and again endlessly.
Important: If the engine is switched off during testing, fault code 12231 will be obtained as the first fault, i.e. rpm signal absent. Run the starter motor for about 5 seconds. If the fault code disappears the ignition signal is OK and the fault is of another kind. As soon as acknowledgment has been received, allow the ignition switch to return to the Drive position and continue testing.
Next fault code
To check whether the system has two or more faults, continue as described below.
6 Set the switch to the "ON" position.
7 After a short flash, set the switch to the "OFF"position.
Fault code No.2 will then be flashed in the same manner as fault code No.1.
If an additional fault is stored in the memory, it will be flashed in the same way as the first fault but with its own fault code.
8 A third fault code, if any, can be retrieved in the same manner. If no third fault is stored in the memory, or if all faults have been rectified, this will be indicated by an unbroken series of long flashes.
Start all over again
If you want to repeat the fault codes from the beginning for any reason, proceed as follows:
1 Set the switch to the "ON" position.
2 After two short flashes, set the switch to the "OFF" position. The fault codes will now be flashed again, starting with fault code No.1.
Clearing the memory
1 Set the switch to the "ON" position.
2 After three short flashes, set the switch to the "OFF" position.
The fault memory is now empty.
Important: The fault memory can be cleared only after code "00000" has been flashed, long flashes (end of fault codes).
Fault codes, self-diagnosis
When faults arise in the LH 2.4 system that can be classified as faults of "memorizing" type, the car must be driven for about 10 minutes so that corresponding fault codes will not reappear even though the fault has been rectified. The reason for this is that the system endeavors to compensate for changes that affect the function in one or the other direction.
When the system compensates for values that are outside the fault limit, the appropriate fault code is generated. When the fault codes are cleared, the memorized fault compensation procedure remains. Before the fault codes are cleared, the system must memorize a fresh compensation procedure.
This compensation procedure takes a certain time for the system to implement, depending on what the fault is. Driving the car for 10 minutes with a warmed-up engine will give the system sufficient time to "learn" and adapt to different conditions.
This applies to the following fault codes;
12223,12224 and 12225 (oxygen sensor signal/preheating)
12111 and 12112 (memorizing fault, oxygen sensor control)
12113 and 12114 (memorizing fault, idle speed control)
Intermittent faults
Intermittent faults of a serious nature cause the "CHECK ENGINE" lamp (MIL) to light up when the fault occurs. When the fault temporarily disappears, the "CHECK ENGINE" lamp (MIL) goes out but the fault code is stored in the memory where it remains.