Scania DCU DTC 785 Micro switch rear door leaf, open circuit in closed position

Applies to: DCU3 (DCUA)DCU3 (DCUF)DCU3 (DCUM)DCU3 (DCUR)

What does Scania DCU fault code 785 mean?

The measured voltage on the 3-phase input indicates an open circuit. This occurs when the voltage is approximately 8 – 16 V with a voltage supply of 24 V to the door control unit.

What causes Scania DTC 785?

- Open circuit due to cable harness damage. - A connector is disconnected. - The micro switch is out of order. - Fault in the door control unit supply pin that goes to external components.

How does the system react?

- The door control unit signals the fault via the CAN network to the main body system (MBS). - An error message is activated and a lamp with an exclamation mark lights up in the instrument cluster for the affected door on the bus stop side.

What are the symptoms?

The door leaf cannot be opened by the door control unit or by hand. Only emergency opening is possible.

How to fix Scania DCU fault code 785?

1. Check the micro switch.
2. Check the cable harness and harness-to-harness connector for the micro switch.
3. Measure the voltage to the door control unit, the input pin (CN2-9).
4. When the door is in the closed position, the voltage should be closer to 24 V (supply voltage).
5. In other cases, the voltage should be 0 V (earth).