Understanding the wiring diagram for your glow plug relay is crucial for a successful TDI engine swap. This article clarifies the differences between the old and new style glow plug relay systems found in Volkswagen TDIs, focusing on manually wiring the older system.
The key difference lies in the relay’s location and integration with the vehicle’s wiring harness. Newer TDI engines incorporate the glow plug relay within the engine harness, located under the windshield near the wiper motor. This simplifies installation, often requiring only a connection to the black/yellow wire from relay 109.
However, older TDIs (like the 2001 Jetta and Golf) utilize an “old style” relay integrated into the cabin harness under the steering wheel. This requires manually wiring the relay after removing it from the cabin harness. This article outlines the wiring process for a 2-pin old style glow plug harness, where each pin powers two glow plugs. Pin 1 powers glow plugs 1 and 2, while pin 2 powers glow plugs 3 and 4.
The old style glow plug relay has seven pins, each with a specific function:
- PIN 1 (Purple/White): Connects to Pin 2 on the beige connector (T6).
- PIN 2 (Red): Connects to the 50-amp fuse (S163) in the fuse box on the battery tray.
- PIN 3 (Brown): Ground this wire to the chassis.
- PIN 4 (Red/White): Connects to one of the pins on the 2-pin glow plug harness connector.
- PIN 5: Empty – no connection.
- PIN 6 (Red/White): Connects to the remaining pin on the 2-pin glow plug harness connector.
- PIN 7 (Green): Connects to Pin 8 on the black connector (T10).
- PIN 8: Empty – no connection.
- PIN 9 (Blue/Black/Yellow): This is the trigger wire that connects to Relay 109. This relay controls power to the glow plugs.
When manually wiring Relay 109, a 6-way relay block can be used. Wiring diagrams for this setup can be found online, often referencing specific relay block models from automotive parts suppliers. These diagrams illustrate how to connect the relay to the ignition switch, battery, and other necessary components.
Successfully wiring the old style glow plug relay requires careful attention to detail and accurate connections. Double-check each wire connection using a wiring diagram specific to your relay and vehicle. Ensure all connections are secure and properly insulated to prevent electrical issues. Using a multimeter to test continuity can help confirm accurate wiring.
