Checking the Data Cable
HINT: The wiring between upper electronic module (UEM) and the rain sensor consists of two cables.
The upper electronic module (UEM) transmits pulses to the rain sensor using the data cable.
Disconnect the rain sensor.
Check that the data is transmitted on the data cable terminal #1 by checking the voltage level between the data and ground cables for the wiring (that is terminals #1 and #2).
HINT: Use the oscilloscope function and check that a pulsed signal is transmitted. The difference between the high and low values of the pulses is approximately 12 V. In the event of an open-circuit in the data cable no pulses are transmitted and a continuous voltage is displayed.
If the difference between high and low values of the pulses is between 2 V and 10 V it indicates that the wiring is oxidized or trapped. Replace the wiring between the rain sensor and the roof wiring in the event of a fault.
If no other fault is found try replacing the rain sensor.
Remedy as necessary.
Other information:
- To access or replace the control module, see Interior Lighting And Upper Electronic Module (UEM), Replacing
- See Rain Sensor
- For further information about signals and other values, see Signal Specification
- To connect the breakout box, see Connecting the Breakout Box
- See Checking Wiring And Terminals .
- Continue
Refer to Verification