A Motronic55 install might save some time with the harness, but you must always verify the harness reasonably carefully. Especially important when deviating from the factory setup, eg. with VemsAudiAanHallHall

This involves

Make your own page for your measurements like MembersPage/TormasiAudiAan, using this as a template. Steps:

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

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.

While injector connectors are disconnected (and ignition output stage also): after applying ECU power (ignition on),

Ignition outputs

For an ignition output end-to-end test, just remove sparkplug high-voltage wires (easier just 1 at a time). make a small 1mm gap to ground (with a wire or a sparkplug) and use the VemsTune spark output test function to see if cylinders fire in the right order (1,2,4,5,3).

Check the spreadsheet (link above) with all the pins. AAN-s use "i259" logiclevel ignouts for ignition, but earlier (perhaps you are fitting an old ECU to another engine/harness), stepper was used on 4 ignition outputs (output amplitude was higher, but also more sensitive to accidental short to GND or +12V).


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

3B ECU extra connector pins: AS YOU LIKE

3B note: motronic55, pin1 is EC18pin11 (stepper-D), see pinout

IF YOU USE DISTRIBUTOR and one ignition output to control spark for all 5 cylinders, you must limit dwell in config. To allow high spark energy at 1.5+ bar boost especially above 7500 RPM, distributorless ignition (or CDI) is needed.

SSC6 feemale for 3B... unspecified

Note that there is NO best, one-pinout fits all pinout for 3B. The 3B extra pinout is made as requested in the order note.


In short: when ordering 3B, in the order comment, you can just write


The more pins used for ignition output, the less of the SSC6 can be analog inputs (useful for ALS, shiftcut, launch,... activation inputs).

When requesting less than 5 channels (2-4) on the SSC6, the 1 pin through the motronic55 is by default logiclevel for active ignition coil (the factory firewall-mounted POS Power Output Stage together with the passive coil is equivalent to a logiclevel coil). As always, of course you can explicitely request power output for the motronic55 ignition pin for passive ignition coil when ordering.

Note that the [VAG active COP] did not fit mechanically into our 1989'3B cylinder head. Might be a good idea to try before relying on it.