: The wiring that passes through the rubber bellows into the doors often cracks over time, leading to window or locking failures. Coolant Temp Sensors
Pro tip: Use the diagram to bridge the starter relay’s "30" and "87" terminals to test if the starter spins—bypassing the immobilizer for diagnosis.
The 306 uses vacuum central locking (early phase 1) or electric motors (phase 2/3). The wiring diagram is critical for the deadlocking circuit (the second turn of the key). Pin 4 of the locking ECU (purple wire) triggers deadlocks. A common fault is broken wires in the driver’s door loom (black rubber boot). The diagram tells you wire colors to cut and splice.
The Haynes manual for the Peugeot 306 (Petrol & Diesel 1993–2001) includes a pull-out section of color wiring diagrams at the back. While simplified, these are 90% accurate for common circuits (starter, alternator, lights, horn, wipers).
Wires are often labeled with 4-digit codes (e.g., 1210 for a specific ignition feed).
