VR6 & ABA Motronic- OBD1 & OBD2

Motronic engine computer for the VR6 (AAA code) and 4 cylinder 2.0 (ABA code) engines. Wiring is substantially similar between all 4 engines, with differences noted below.

Bosch manufactures this system. The OBD1 system is called Motronic M2.9 (M2.9.1 for engines with coil pack), and OBD2 is called Motronic M5.9.
A2Resource > Electrical Systems > Management > VR6 Motronic- OBD1 Pinout

Engine Control Unit:

Pin Function Color, VR6 OBD1 Color, ABA OBD1 Color, ABA OBD2 Color, VR6 OBD2
1 Ground Brown Brown/Red Brown/Red Brown/Red
2 Cylinder Injector Gray/Yellow (Injector 6) White/Gray (Injector 2) White/Gray (Injector 4) Gray/Blue (Injector 4)
3 Cylinder Injector Gray/Green (Injector 2) - - Gray/Black (Injector 5)
4 Cylinder Injector Gray/Blue (Injector 4) - - Gray/Yellow (Injector 6)
5 Check Engine Light Yellow/Black Yellow/Black Yellow/Black Yellow/Black
6 Fuel Pump Relay Turn-On Yellow/Blue Yellow/Blue Yellow/Blue Yellow/Blue
7 Ground (also Auto. Trans. Harness, for PNP Relay) Brown/Red Brown/Red Brown/Black (also Brown/Red- auto. only) Brown/Black
8 Coil Pack Pin 2 (VR6 Coilpack), Coil Signal (ABA, VR6 Dist.) Black/Brown or Black Red (Dist.) Black/Red Black/Red Black/Brown
9 Engine Electronics Relay (3) Turn-On Black/Brown Black/Brown - -
10 Ground (OBD1 EGR enable), Throttle Valve Motor Switch (OBD2) Brown/White or White Brown/White or White
 Red/Green
 White
11 Automatic Transmission Control Module Blue/Yellow Blue/Yellow Blue/Yellow Blue/Yellow
12 Oxygen Sensor 1 Heater Ground - - Brown Brown
13 Oxygen Sensor 2 Signal Black/Yellow (late 94+Corrado only) - White/Red White/Red
14 Coolant Temperature Sensor Blue Blue Blue Blue
15 EGR Temperature Sensor Violet Violet Violet (not connected to sensor) -
16 Mass Airflow Sensor Ground Brown/Blue Brown/Red Brown/Blue Brown
17 Mass Airflow Sensor Signal Red Red Blue Blue
18 Automatic Transmission Control Module Yellow/Red Yellow/Red Yellow/Red Yellow/Red
19 Power for MAP and Acceleration Sensors (late 94+ Corrado) Yellow/Black - - -
20 Oxygen Sensor 1 Signal White White White White
21 Data Link Connector (L-Line) Yellow Yellow Yellow (Automatic Only) Yellow (Automatic Only)
22 Tachometer Output Green/Black Green/Black Green/Black Green/Black
23 Power From Engine Electronics Relay (3) Output (OBD1), Fuse 15 Power (OBD2) Red/Blue Red/Blue Black/Yellow Black/Yellow
24 Cylinder Injector Gray (Injector 1) White/Black (Injector 1) Gray (Injector 1) Gray (Injector 1)
25 Cylinder Injector Gray/Black  (Injector 5) White/Green (Injector 3) Gray/Green (Injector 2) Gray/Green (Injector 2)
26 Cylinder Injector Gray/Red (Injector 3) White/Blue (Injector 4) Gray/Red (Injector 3) Gray/Red (Injector 3)
27 Idle Air Control Valve (OBD1), Throttle Valve Motor + (OBD2) Red/Blue White Black Black
28 Heated Oxygen Sensor Relay Turn-On, Oxygen Sensor 1 Heater Ground (late 94+ Corrado) White (Brown- late 94+ Corrado) White - -
29 - - - - -
30 EGR Vacuum Regulator Solenoid Valve (Change-Over Valve- late 94+ Corrado) Green/Gray Green/Gray Green/Gray (not connected to valve) Green/White
31 Evap. Canister Purge Regulator Valve Green/Yellow Green/Yellow Green/Yellow Green/Yellow
32 Acceleration Sensor (late 94+ Corrado) White/Gray - - -
33 Sensors Ground (Knock, Coolant, Throttle, Exhaust Gas Temp, Intake Air Temp, RPM, Manifold Pressure, Acceleration Sensors) Brown Brown Brown/Blue Brown/Blue
34 Knock Sensor 1 Gray Gray Gray Gray
35 Leak Detection Pump, Fuel Cut-off Valve (A3) - - Yellow/Brown -
36 Intake Air Temperature Sensor Blue/Green Blue/Green White/Gray Blue/Green
37 Air Conditioning "On" Switch (At Compressor) Green Green Green Green
38 Ignition Switch Start/Run Power Black/Green Black - -
39 Air Conditioning "On" Switch (Inside Cabin) Blue/Red Blue Blue Blue/Red
40 Throttle Position Sensor Signal 1 Green/White Green/White or Green/Gray Red/Blue Green/White
41 Throttle Position Sensor Power Black/Gray Black/Yellow (also cam position sensor) Red/White Black/Gray
42 Oxygen Sensor 1 Sensor Ground (Shared for both sensors- late 94+ Corrado) Yellow Yellow Yellow Yellow
43 Data Link Connector (K-Line) Gray/White Gray/White Gray/White Gray/White
44 Camshaft Position Sensor White/Red White/Red Green/White White/Red
45 - - - - -
46 Leak Detection Pump (A3) - - Gray/Violet -
47 Oxygen Sensor 2 Heater Ground (late 94+ Corrado) Red/Brown - - -
48 - - - - -
49 Secondary Air Injection Relay Turn-On Red/Gray - Gray/Brown Red/Gray or Gray/Brown
50 (Various- ground-switched) Red/Yellow (N180 Change Over Valve- Passat), Red/Gray (AIR Relay, Ctrl. No. 111- Corrado from late 1993) Red/Gray (AIR Relay, Ctrl. No. 111) Red/Yellow (N112 AIR Solenoid Purge Regulator Valve) Red/Yellow (N112 AIR Solenoid Valve)
51 To Instrument Cluster (MFA MPG) Violet/White Violet/White Violet/White Violet/White
52 Coil Pack Pin 4 Black/Violet - - Black/Violet
53 Idle Air Control Valve (OBD1), Throttle Valve Motor - (OBD2) Black/White Black/White White Black/White
54 Battery Power Red/Yellow Red/Yellow Red Red
55 Ground Brown/Black Brown/Black - -
56 Ground Brown/White Brown/White Brown/Black Brown/Black
57 Knock Sensor 2 Yellow or Green/Yellow - - Yellow or Green/Yellow
58 Ground (OBD1 Automatic Only), Oxygen Sensor 2 Sensor Ground (OBD2) White White Yellow or Black/Yellow Yellow or Black/Yellow
59 Mass Airflow Sensor Black - - -
60 Coil Pack Pin 3 Black/Blue - - Black/Blue
61 - - - - -
62 Throttle Position Sensor Signal 2, or MAP Sensor (Corrado) White/Green (late 94+ Corrado only) - Red/Gray Red/Gray
63 - - - - -
64  - - - - -
65 Vehicle Speed Sensor Blue/White White/Yellow White/Yellow Blue/White
66 Oxygen Sensor 2 Heater Ground Brown/White (late 94+ Corrado only) - Brown Brown
67 Engine RPM Sensor Ground Red Red Red Red
68 Engine RPM Sensor Signal Green Green Green Green