Transmission Control Systems: Testing and Inspection

Checking data lead from the EWS to the [1][2]DME/DDE control module

Oscilloscope measurement with metrology in the DIS

When doing this, proceed as follows:
- Install test adapter between [1][2]DME/DDE and vehicle wiring harness. Proceed in accordance with the wiring diagram.
On the M73, EWS2 or EWS 3.2: [1][2]DME1 on the M73, EWS 3.3: First test for DME1, then for DME2
- Carry out oscilloscope measurement between terminal 31 (control module) and EWS data lead
- Measuring cable: MFK1
- Measuring channel: Channel A
- Measuring range: ±20 V
- Voltage form: =
- Frequency range: 40 Hz
- Terminal 15 ON

IMPORTANT: During the measurement, the [1][2]DME/DDE must be connected.

The following illustration shows the oscilloscope image of a measurement on a data







Signal OK

Note that the statement "OK" only refers to the data lead and the signal form. It is unable to determine whether the transmitted code is correct.

If it is still not possible to start the engine:

EWS 2, EWS 3.2: Conduct a data comparison EWS-[1][2]DME/DDE







Signal not OK

The above signal indicates a fault in the [1][2]DME/DDE.

Continue fault finding in the [1][2]DME/DDE diagnosis program with the fault symptom







Signal not OK

- U = approximately battery voltage:
Check wiring and repair if necessary. If the wiring is OK: continue fault finding in [1][2]DME/DDE
- U = approximately battery voltage - 1 V (approx. 1 V lower than battery voltage)

Control modules and wiring are OK. Use diagnosis requests to ensure that the







Signal not OK

The above signal indicates a short to ground or a line break. Check EWS-[1][2]DME/DDE data link and repair if necessary. If data link is OK, replace EWS control module.