Diagnose ECU (DE)

The Diagnose ECU (DE) is a small PCB inside the 928 LH unit. The DE is connected together with other ECU's like EZK, RDK, PSD etc on the diagnose bus of the 928. Many sensors are connected from the LH towards the DE. Sensors like: MAF, Lambda sensor, Temperature, Idle stabalizer, Injectors, Load signal, Fuel pump control, Throttles, Speed etc. With the 928-ecu-repair diagnose tools UDT999 and PDT999 it is possible to read these additional sensors. The DE contains also two LED output signals. It is possible to map for instance the Lambda sensor value (rich / poor) towards these LEDS. During a testdrive the user is able to check if the Lambda sensor is correct. But also other sensor values are possible to map on these LEDS, like the throttles.

Why an additional Diagnose ECU inside the LH ? Simple because the diagnose capabilities of the LH are limited. And it is not possible to measure LH sensor values when the car is driving at speeds above 1500 rpm.



Diagnose ECU build in 928 LH unit.


Below you see a screendump of the UDT999 PC-tool. It is possible to select multiple sensors and during measurement, the UDT writes all samples towards a log file.


Screendump UDT999.

Which sensors are connected to the DE today ?
  • Mass Air Flow (MAF).
  • Lambda / OXY sensor.
  • Engine temperature.
  • Idle stabalizer.
  • Injector signal.
  • Load signal.
  • Throttle idle and throttle full.
  • Fuel pump output signal.


    • The DE contains also two drivelink signals, which the user can use for selecting a different eprom bank. The eprom contains MAP-parameters and with selecting an other bank, the user selects for instance more sportive MAP parameters. My colleque Theo has build up quite some different MAP parameters to play with :-).