Audi A2 Conversion

On this page we describe the conversion of an Audi A2 1.4i petrol to electric propulsion. We will use the following components:

• Nissan Leaf 24 kWh battery pack with original BMS
• Toyota Prius Gen 2 (2004-2009) transaxle with matching inverter
• openinverter Prius Gen2 motor controller
• openinverter main board running stm32-car (VCU in ECU enclosure)

Pin mapping

We start out by mapping out useful pins of the original wire harness

ECU

The ECU has two connector slots, a smaller one with pins 82-121 and a larger one with pins 1-81. Here we map out pins useful to us

ECU pinout 1.4i (AUA, BBY)

#	orig function	our function	wire color
1,2	GND	as is	br
3	permanent 12V		ro
4	ignition 12V	as is	ro/sw
5	Lambda (first) heater	Reverse light	gr
28	From generator (maybe DF)		li/bl
33	Throttle second pot +5V	as is	gr/ge
34	Throttle second pot (signal)	as is	br/gn
35	Throttle first pot (signal)	as is	ge/bl
36	Throttle first pot +5V	as is	br/ro
38	To cruise control switch * if installed		ws
39	Clutch pedal sensor * if installed		ro/ge
40/41	To Climate control display		sw/ge sw/gr
43/54	To instrument cluster (function unknown)		gn/sw bl/ws
51/52	Lambda (first) signal	CAN for Prius	bl/ws ge
55/56	Brake light switch NC/NO to +12V		ws/ro ro/sw
57	To cruise control switch * if installed		bl/ro
58/60	CAN-L CAN-H	as is	or/br or/sw
63	Lambda (second) heater		li/ro
64	Charcoal filter solenoid	vacuum pump GND	bl/ge
65	Fuel pump relay- control		ro/br
68/69	Lambda (second) signal		bl/br ro/li
70/71	Lambda (first) signal	LIN for A/C, fake oil pressure	bl sw
72	Throttle second pot GND	as is	gr
73	Throttle first pot GND		ge/li
75/76	To cruise control switch *		bl/sw sw/ro
82	Engine speed sensor		gr/br
85	Intake manifold Temp/Pressure	brake vacuum	gr
86	Hall sender G40 signal		ro/sw
87	Engine speed sensor		gn/sw
88/89 96/97	Injector 1-4		sw/li li/sw br/bl sw/gn
83/84 91/92 117/118	Throttle body senror Throttle body sensor Throttle body motor		ro/gn gn/bl ro/bl li/ro gn br/sw
93	Coolant temp sensor		gr/ws
98	+5V wiring to engine bay	as is	gn/li
99	Knock sensor		ws
100 114	EGR pot EGR mot		br/li li/ge
102/103	Ignition coil bank 1/2	Fake oil level	gn/ws gn/ro
106	Knock sensor		br
108	GND for engine sensors	as is	gr/ro
109	Intake manifold Temp/Pressure		bl/gn

ECU pinout 1.6FSI

#	Org Function	Ours	Color
1/2	GND		br br
3/5	permanent 12V		gn/ge gn/ge
4/20/21 39/40	First Lambda		ge ro/ge bl/ge br/ge li/gr
6	N290 Fuel metering valve		ro/bl
7	Fuel pump relay control		ro/br
8/10	CAN-H CAN-L		or/sw or/br
11/16/31 32/50	NOX controller		sw br/ws bl ws/sw ge/ro
12	Heater output switch		ge/br
13/17/30	Air mass meter		gr/ro gr/ws li/ws
14	Thermo-switch for coolant circulation		ro/ws
15/18/43 33/19/24	Throttle POT1/2 (signal/Gnd/+5)		ge/li br/ro ge/li br/gn gr/ge gr
23/46	Climate cotroler		sw/gr sw/ge
26/45	Radiator fan controller		sw/ge ge/gr
35	EGT		ro/gn
36	Brake vaccum sensor		bl/br
37	Sensors GND		ge/bl
48/57	Brake light switch NO/NC		ro/sw ws/ro
42	+5V to sensors		ge/gn
49/51/52/55	Cruise control switch * If installed		bl/sw ws sw/ro bl/ro
53	To airbag ECU		ws/bl
59	Instrument cluster		gn/sw
60/80	NOX heater		br/ws br/ws
62/64	Current supply relay		ro gr/ro
65	Generator DF		li/br
67	Clutch pedal switch * if fitted		ro/ge
78	N79 crankcase breather heater		br
81/100/101 108/109	Coils		ro/sw ro/bl ge/gn ge/bl gn/ge
82/90	G28 Engine speed sensor		gr/br gr/ro
83	G40 Hall sender		br/bl
84	G71 Intake manifold pressure sens		ge/ro
85/87/96	EGR sensor + motor		li/gr li/ws ro/ws
86	Coolant temp sensor		gr/ws
88	N316 Intake manifold flap valve		li/ge
89	F265 Controlled cooling thermostat		ro/br
91	G336 Intake flap potentiometer		ge/ro
94	G247 Fuel pressure sensor		gr
99	+5V to sensors		li/ro
105	N205 Inlet Camsh. timing valve		li/gn
113	N276 Fuel pressure regulating valve		gn/bl
92/93102 107/118/121	Throttle body		li/ge li/gr ws ro/gn ro/bl li
103/110/111	Knock sensor		br br ws
106	Sensor gnd in engine bay		gr/gn
114/115 116/117 119/120	Injectors 1-4		br/ge br/ws br/gn br/ro br/bl br/sw

Silence errors

After disconnecting the engine and removing the ECU we have 3 errors: Low coolant level, low oil, ABS/ESP. Coolant level can be silenced by simply shorting out the corresponding sense pins. We will use the coolant reservoir of the Prius inverter. We might insert a sensor for super neat integration, but not for now.

Low oil can probably be cured by coding of the instrument cluster like in Touran:

I programmed the instrument cluster to ignore the missing sensor. You need a CAN OBD adapter with matching software. Then in adaptation channel 39 change value to 0 (=sensor not present). Found here: http://wiki.ross-tech.com/wiki/index.php/VW_Golf_(1K)_Instrument_Cluster

And finally ESP is silenced by sending appropriate CAN message as stm32-car does.