For enthusiasts and mechanics undertaking engine swaps or simplifying their 1.9 TDI ALH engine wiring, understanding the OBD2 harness is crucial. This guide breaks down the essential connectors and ECU pinouts required to run your 1.9 TDI ALH engine, specifically focusing on a streamlined harness configuration. This information is compiled from a detailed analysis of the harness, tracing wires component by component to ensure accuracy for your project.
Essential Connectors and Pinouts for 1.9 TDI ALH OBD2 Harness
This section details the critical connectors on the 1.9 Tdi Alh Obd2 Harness needed for engine operation. Note that this configuration assumes the removal of the EGR system, while retaining the anti-shutter valve (though it’s not strictly necessary for running the engine). Fuse ratings are provided for protection and proper circuit operation.
Fuse Box Configuration
- ECU Fuse: 30A
- Sensors Fuse: 10A (Yellow/Black wire)
- Switched Power Fuse: 10A (Black/Purple wire – connected to ignition switch)
- Coolant Glow Plug Relay Ignition Fuse: 10A
Relay 109
- Replaced with a Bosch 30A relay for enhanced reliability.
Power and Ground Connections
- Light Blue Wire: Power supply to fuses/ECU
- Red Wire: 50A
- Blue/Yellow Wire: ECU Pin #18 Relay Supply
- Bolt/Flat Thing: Ground connection point
Coolant Glow Plugs Connector
- Black/Brown Wire: ECU Pin #22 (High)
- Black/Blue Wire: ECU Pin #21 (Low)
- Blue/Yellow Wire: 10A Fused power supply
Glow Relay Connector
- Pin 1: Purple/White wire – ECU Pin #42
- Pin 2: Red wire – 50A Battery power
- Pin 3: Brown wire – Ground (Bolt)
- Pin 4 & 6: Red/White wire – Glow Plugs
- Pin 9: Blue wire – 10A Fused power supply
- Pin 7: Green wire – ECU Pin #33
MAF Sensor Connector
- Pin 2: Yellow/Black wire
- Pin 3: Green wire – ECU Pin #49
- Pin 4: Red/Green wire – ECU Pin #30
- Pin 5: Black wire – ECU Pin #68
MAP Sensor Connector
- Pin 1: Brown/Blue wire – ECU Pin #52
- Pin 2: Grey/Green wire – ECU Pin #73
- Pin 3: Violet/Red wire – ECU Pin #31
- Pin 4: Yellow/Black wire – 10A Fused sensor power supply
N75 Valve Connector
- Pin 1: Yellow/Black wire – 10A Fused sensor power supply
- Pin 2: Red/Brown wire – ECU Pin #62
Anti-Shutter Valve Connector
- Pin 1: Yellow/Black wire – 10A Fused sensor power supply
- Pin 2: Violet/Purple wire – ECU Pin #81
TPS (Throttle Position Sensor) Connector
- Pin 1: Green/Red wire – ECU Pin #51
- Pin 2: White/Blue wire – ECU Pin #63
- Pin 3: Yellow/Green wire – ECU Pin #12
- Pin 4: Grey/Red wire – ECU Pin #50
- Pin 5: Grey/Blue wire – ECU Pin #69
- Pin 6: Grey/White wire – ECU Pin #70
Alternator Connector
- Pin 1: Brown/Red wire – W-wire, ECU Pin #38
- Pin 2: Blue wire – Alternator light
- Pin 3: Green/Black wire – A/C Clutch
- Pin 4: Brown/Black wire – A/C Clutch
14-Pin Connector
This connector interfaces with various engine sensors. Wire colors may vary; verifying connections is crucial.
- Pin 1 (Connector Side): Green/Black wire (Oil Pressure Lamp) – Pin 1 (Engine Side): Black wire
- Pin 2 (Connector Side): Large Black/Green wire – Pin 2 (Engine Side): Black/White wire
- Pin 3 (Connector Side): Green wire – Pin 3 (Engine Side): White/Black wire
- Pin 4 (Connector Side): Purple wire – Pin 4 (Engine Side): Purple wire
- Pin 5 (Connector Side): Red/Violet wire (30A Fuse w/ECU) – Pin 5 (Engine Side): Red/Purple wire
- Pin 6 (Connector Side): Yellow/Black wire (10A Fused Sensor) – Pin 6 (Engine Side): Yellow/Black wire
- Pin 7 (Connector Side): Brown wire (Ground – Bolt) – Pin 7 (Engine Side): Brown wire
- Pin 8 (Connector Side): Black/Purple wire – Pin 8 (Engine Side): Empty
- Pin 9 (Connector Side): Brown/White wire – Pin 9 (Engine Side): Brown/White wire
- Pin 10 (Connector Side): Small Black/Green wire – Pin 10 (Engine Side): Black/Green wire
EDC15VM+ ECU Pin Assignments
This section lists the ECU pin assignments relevant to the harness connectors detailed above. Understanding these pinouts is essential for troubleshooting and custom wiring.
- Pin 12: Yellow/Green – TPS Pin 3
- Pin 18: Blue/Yellow – Power Relay
- Pin 21: Black/Blue – Coolant Plugs Low
- Pin 22: Black/Brown – Coolant Plugs High
- Pin 30: Red/Green – MAF Pin 4
- Pin 31: Violet/Red – MAP Pin 3
- Pin 33: Green – Glow Relay Pin 7
- Pin 38: Brown/Red – W-wire Alt Pin 1
- Pin 42: Purple/White – Glow Relay Pin 1
- Pin 49: Green – MAF Pin 3
- Pin 50: Grey/Red – TPS Pin 4
- Pin 51: Green/Red – TPS Pin 1
- Pin 52: Brown/Blue – MAP Pin 1
- Pin 62: Red/Brown – N75 Pin 2
- Pin 63: White/Blue – TPS Pin 2
- Pin 68: Black – MAF Pin 5
- Pin 69: Grey/Blue – TPS Pin 5
- Pin 70: Grey/White – TPS Pin 6
- Pin 73: Grey/Green – MAP Pin 2
- Pin 81: Violet/Violet – Anti-Shutter Pin 2
- Pin 101: Blue – #3 Injector Pin 1
- Pin 104: Brown/Green – Coolant Temp/Level Sensor Pin 4
- Pin 109: Grey – #3 Injector Pin 2
- Pin 110: White – Oil Level Sensor Pin 1
Engine Sensor and Component Wiring (Secondary Harness)
This section outlines the wiring for sensors and components on the engine side, often connecting to the 14-pin connector.
Oil Pressure Sensor
- Pin 1: Green/Black wire – 14-Pin Connector Pin 1
Oil Level Sensor
- Pin 1: White wire – ECU Pin #110
#3 Injector Connector
- Pin 1: Blue wire – ECU Pin #101
- Pin 2: Grey wire – ECU Pin #109
Coolant Temperature/Level Sensor Connector
- Pin 4: Brown/Green wire – ECU Pin #104
This guide provides a detailed breakdown of the 1.9 TDI ALH OBD2 harness wiring, essential for anyone simplifying or adapting this engine’s electrical system. Always double-check wire colors and pin locations to ensure correct connections and prevent damage to your ECU or engine components.
