Applies to: CMS1 (CMS)
What does Scania CMS fault code 660 mean?
The output to the power steering electrohydraulic pump (M55), connected on PWM output 3 (Pin: signal A15, ground A13) is either not connected or is short-circuited to voltage.
What causes Scania DTC 660?
The fault may be due to: - Fault in the cable harness. - Short circuit to voltage. - Not connected. - Fault in the harness-to-component connector. - Fault in the electrohydraulic pump solenoid.
What are the symptoms?
The fault code covers two different faults which cannot be separated electrically. - If the cause is a break in the circuit or a fault in the electrohydraulic pump solenoid, the differential lock cannot be activated. - If the cause is a short circuit to voltage supply, the electrohydraulic pump will remain active.
How to fix Scania CMS fault code 660?
- Check the cable harness and connections to the electrohydraulic pump (M55) from control unit PWM output 3 (Pin: signal A15, ground A13).
- Check the electrohydraulic pump solenoid as follows:
- Measure the resistance between the inputs to M55.
- Resistance should be approximately 20 ohms.
- Measure the resistance between the outputs on M55 to the electric motor when the solenoid is not supplied with voltage.
- Resistance should be infinite.
- Measure the resistance between the outputs on M55 to the electric motor when the solenoid is supplied with voltage.
- Resistance should be a few ohms.
- Measure the voltage when the solenoid is actuated between PWM output 3 (signal, pin A15) and ground.
- The voltage should be 24 V.
This information is for guidance only. Always follow the manufacturer workshop manual and safety procedures; if in doubt, contact an authorised workshop.