Motronic

Motronic is a much simplified CIS-E system. It is similar to Jetronic in many ways, but also very different. It still uses a mechanical fuel distributor, but has much finer control of the engine. It has integrated knock, ignition, and oxygen sensor control in one control unit. It's coil has a power stage as well. It is also the first CIS system with integrated fault memory and diagnosis. This, coupled with the ability to be fitted with an EGR system, made Motronic suitable for installation in all 50 states (California having the EGR system and OBD fault warning light installed). It was only available on the 2.0 16v. Motronic operates very similarly to Jetronic, except that it is digital, and combines multiple functions into one control head. It takes into account coolant temperature, oxygen content of the exhaust, engine speed, vehicle speed, knock (via 2 sensors), timing, basic throttle position, and EGR temperatures (California only) to control basic fuel metering via the differential pressure regulator, fully control idle air, and adjust timing as well. It also has built-in cold start control (Jetronic relies on an external thermo-time switch and cold start valve). The differential pressure regulator current can be the most telltale test applied to a Jetronic or Motronic vehicle to diagnose it's operating condition (provided everything else is in working order).

Motronic Engine Controller:

Pin Function Color, 1990 GLI, 1990-early 1991 GTI Color, 1991+ GLI, late 1991+ GTI Color, Passat
1 Diagnostics K-Line Gray/White Gray/White Yellow/White
2 Speed Sensor Blue/White Blue/White Blue/White
3 Coolant Temperature Sensor Black/Violet Violet/Black Violet/Black
4 Differential Pressure Regulator Red/White White/Red White/Red
5 Differential Pressure Regulator Brown/Blue Brown/Blue Brown/Blue
6 Knock Sensor 2 Shield Green White Gray
7 Oxygen Sensor Black Black Black
8 Knock Sensors Signal Yellow (Sensor 1), Blue (Sensor 2) Blue (Sensor 1), Yellow (Sensor 2) Yellow (Sensor 1), Blue (Sensor 2)
9 EGR Temp Sensor (1991+ GTI and GLI) Blue/Yellow Blue/Yellow Violet
10 - -

11 Tachometer signal from ignition booster Green Green Green
12 Fuel Pump Relay Red/Yellow Red/Yellow Red/Yellow
13 Check Engine Light Yellow/Black Yellow/Black Yellow/Black
14 Start/Run Power Black Black Black
15 Charcoal Canister Solenoid Valve 1 Yellow/Green Green/Yellow Green/Yellow
16 Cold Start Valve Black/Red Black/Red Black/Red
17 Idle Stabilizer Valve Brown/Yellow White White
18 Ground to head (also used for Charcoal Canister Cut-Off Vlv. Ground) Brown/Yellow Brown/Yellow Brown/Yellow
19 Battery Power Red Red Red
20 Ground - - Brown/Black
21 Distributor Pin 3 (positive) Red/Black Red/Black Red/Black
22 Diagnostics L-Line (code signal) Yellow Yellow Yellow
23 Air Flow Sensor Potentiometer Gray/Green Gray/Green Gray/Green
24 Knock Sensor 1 shield White Gray (GTI) or Green (GLI) White
25 Tachometer signal from coil pin 1 (tach gauge) - - Green/Blue
26 Air Flow Sensor Potentiometer Gray/Red Gray/Red Gray/Red
27 Ignition Timing Sensor Brown Green Blue/Black
28 WOT Switch Black/Blue (GLI) or Black/Yellow (GTI) Black/Blue (GTI) or Gray (GLI) White/Red
29 Ignition Timing Sensor White Red Blue/Black
30 Distributor Pin 2 (hall sensor) Green/White Green/White Green/White
31 A/T Controller - - Yellow/Red
32 Idle Switch Black/Blue (GTI) or Black/Yellow (GLI) Gray (GTI) or Black/Blue (GLI) Yellow/Violet
33 A/C compressor signal Green Green Black/Green
34* Ground to fuse box (battery ground) Gray/Red White/Green -
34* Starter Power - - Red/Blue
35 Ground to head Brown Brown Brown
*Note: on automatic Passats, pin 34 sends power to the ECU when the starter is running. On all A2s, this pin is always grounded.