With Impulse Counter

Diagnosis

Test conditions:

Coolant temperature 60-80 °C
Automatic climate control off.
Selector lever in position "P"
Base module fuse OK (perform base module impulse readout, socket 8).
Battery voltage approx. 12 volts at EDS control unit socket 1.

NOTE: Do not disconnect the battery, unplug the base module or EDS control unit (N39) before recalling the stored malfunctions via the impulse readout (otherwise stored malfunctions will be erased from memory).

Special Tools

Special Tools and Equipment:

Connection Diagram






013 Impulse counter
075 Impulse counter adaptor
X11/4 Test connection for diagnosis (impulse readout) (X11/4 38-pole)

Layout of impulse counter adaptor:

1 Ground, circuit 31
2 Circuit 87
3 Circuit 30
4 EDS impulse readout

Note Regarding Impulse Readout:
If the impulse readout does not indicate a malfunction in spite of a complaint, perform function test. Function Test, Elec. Idle Spd., Control (ELR), EGR, P2-Control

The number "1". indicates that there are no recognized malfunctions in the electronic system. All further numbers refer to a particular component or malfunction source.

Numbers ranging from 1 to 15 may be displayed on the impulse counter.

If the LED "U-Batt" lights after connecting the impulse counter, then the impulse counter and voltage supply for the impulse counter are ok.


1. Connect impulse counter according to connection diagram.

Note: LED "U-Batt" in display must light up. otherwise:
a) Check impulse counter fuse.
b) Check socket 1 of test connection (X11/4) against the positive pole of the battery (11-14 V).
c) Check socket 4 of test connection (X11/4) against socket 1 (6-12 V).

2. Engine at idle.
If the malfunction memory is read using the impulse counter with the ignition ON and the engine not running, impulse readout "7" (starter ring gear speed sensor - L3) will appear.

3. Press start button for 2 to 4 seconds.
4. Read and note impulse readout displayed.
Display "1" = no malfunction stored.
Greater than "1" = malfunction in system.
5. Press start button again for 2 to 4 seconds. If there are no further malfunctions in the system, the previously displayed number will reappear. If additional malfunctions exist, then the respective malfunction code will be displayed.
6. Repeat step 5 until the first number displayed is repeated.
7. Eliminate noted malfunctions (impulse readout) according to troubleshooting chart.
8. Perform tests of individual components.

Erasing Malfunction Memory:

After eliminating a malfunction, the respective impulse readout must be cleared as follows:

9. Press start button and read out the eliminated malfunction. Then press the start button for 6 to 8 seconds.

Note: Each malfunction displayed must be erased individually. If the malfunction has been eliminated and its respective readout erased, then the malfunction code will no longer be displayed when performing the impulse readout. If the number displayed is greater than 1, then there are further malfunctions in the system.