=== UrS?4 - 5 cyl - ANN Turbo - PnP? VEMS===

Basic Info:


Ordered motronic55 ECU:

Installation Checklist

Documents and files to use

This is the most important docs, so you know pinout and function mapping. In VemsTune you will see names like EC36pin10 while you have it wired to some motronic pin. While you do the measurements, write the measured value and the pin you used, and any notes you think appropriate

Config and tables

Find the quick method on VemsTune/QuickStartAudi. For boxes sent out after 2008-07-31 check the "Cam HALL Inv." checkbox in the "Upload Config Files" step.

This quick method is useful because the config is split to basic, trigger, injector and ignout sections to support combinations of 3B and AAN engines with different injectors, with or without cam-HALL inverter and different ignition output setups.

Firmware and tuningsoftware

Sensor measurements

Or make your own through EasyTherm. Measure sensor resistance against AANpin30.

Take note of the temperature. If the engine is stopped for hours, the coolant and MAT will be close to ambient temperature.

Injectors and idle-air output measurements

Measure injector and idle air pins against AANpin37 (that is the flyback pin, same function as EC36pin23 in standard VEMS docs)

The firing order is 1-2-4-5-3 and it's ok to shift this table, it keeps the injector firing order.

Ignition outputs

Check the spreadsheet (link above) with all the pins.

( TODO: Very important. This changed to different pins on the ECU board. Config can not be re-used easily from older ECUs. When, after what date? which serial nrs are affected? )

Very old Motronic harnesses and ECU have swapped cylinder 1 and 3, which are AANpin1 and AANpin23, only very few were made this way.

If in doubt, just remove sparkplug high-voltage wires (easier if 1 at a time). make a small 1mm gap to ground (with a wire or a sparkplug) and used the spark output test function from within the tuning software to see if cylinders fire in the right order. It is recommended to do this for all 5 cylinders as an end-to-end test.


Measure that grounds are strongly (max 0.1 Ohm) connected inside the VEMS ECU.

Measure ECU pins: verify that all the above grounds are connected inside the ECU.

Measure that first 3 are connected in the harness. AANpin30 (sensor ground) and AANpin48 trigger ground are likely not connected inside the harness.


The secondary trigger crankhome-VR MUST BE reversed. Can be done in the connector on the firewall.

Measure trigger resistance against AANpin48.

Reversing crankhome-VR polarity

Location of the trigger plug:


Wiring crank home normal:


Swap the red and violet wire:


The wire is swapped:


HALL signal

WBO2 on SSC5 male standard applies to both Audi AAN and 3B (also to BMW):

OBSOLETE SSC4 male WBO2. was used before 2007-08 (now SSC5 is used)

AAN ECU extra connector pins:

SSC6 feemale

Extra Econoseal 10 pin connector