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
| # | 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 | 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 | 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 | 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 | gn/ws gn/ro | |
| 106 | Knock sensor | br | |
| 108 | GND for engine sensors | as is | gr/ro |
| 109 | Intake manifold Temp/Pressure | bl/gn |
| # | 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.