Scania SC DTC 4 Voltage supply

SC SC control unit · Scania · 6 variants

Code 4 (decimal). Some diagnostic tools show it in hexadecimal as 0004.

In short

The voltage supply to the tachograph has been missing.

Variant 1

Applies to: SC1 (TCO)

What does Scania SC fault code 4 mean?

The voltage supply to the tachograph has been missing.

What causes Scania DTC 4?

- Short circuit or open circuit in the tachograph power supply. - The batteries have been disconnected.

How to fix Scania SC fault code 4?

  1. Note: When disconnecting the batteries: put a workshop card in the tachograph before disconnecting to avoid the fault code being set when the batteries are reconnected.
  2. Check the circuit for short circuits and open circuits.

Variant 2: Voltage supply to the tachograph

Applies to: SC2 (TCO)

Detection

The voltage supply to the tachograph has been outside of the permitted range – either above 33 V or below 8.6 V. The tachograph display shows code 31 for this fault code.

Possible cause

- Too low a voltage can be caused by a short circuit or open circuit in the cable harness for the tachograph voltage supply. Voltage can also be temporarily too low during start-up. - The fault code can also be caused by the tachograph temporarily receiving too high a voltage.

How to fix

  1. Check the voltage supply to the tachograph.
  2. Check the cable harness and harness-to-harness connectors.
  3. Check whether other systems have generated a fault code for voltage supply.

Variant 3

Applies to: SC3 (TCO)

Detection

The voltage supply to the tachograph has been missing.

Possible cause

- Short circuit or open circuit in the tachograph power supply. - The batteries have been disconnected.

System reaction

A fault message is shown in the tachograph display.

How to fix

  1. Note: When disconnecting the batteries: put a workshop card in the tachograph before disconnecting to avoid the fault code being set when the batteries are reconnected.
  2. Check the circuit for short circuits and open circuits.

Variant 4: Voltage supply to the tachograph

Applies to: SC4 (TCO)

Detection

The voltage supply to the tachograph has been outside of the permitted range – either above 33 V or below 8.6 V.

Possible cause

- Too low a voltage can be caused by a short circuit or open circuit in the cable harness for the tachograph voltage supply. Voltage can also be temporarily too low during start-up. - The fault code can also be caused by the tachograph temporarily receiving too high a voltage.

System reaction

A fault message is shown in the tachograph display.

How to fix

  1. Check the voltage supply to the tachograph.
  2. Check the cable harness and harness-to-harness connectors.
  3. Check whether other systems have generated a fault code for voltage supply.

Variant 5: Voltage feed

Applies to: SC5 (TCO)

Detection

The voltage supply to the tachograph is missing.

Possible cause

- Short circuit or open circuit in the tachograph power supply. - The batteries have been disconnected.

System reaction

An error message is shown in the tachograph display.

How to fix

  1. Note: When disconnecting the batteries: put a workshop card in the tachograph before disconnecting to avoid the fault code being set when the batteries are reconnected.
  2. Check whether there is a short circuit in the cable harness.
  3. Check whether there is an open circuit in the cable harness.
  4. Check the connectors.
  5. Check the battery capacity.
  6. Check the voltage supply voltage from the alternator.

Variant 6: Voltage supply to the tachograph

Applies to: SC6 (TCO)

Detection

The voltage supply to the tachograph has been outside of the permitted range – either above 33 V or below 8.6 V.

Possible cause

- Too low a voltage may be caused by a short circuit or open circuit in the cable harness for the tachograph voltage supply. Voltage can also be temporarily too low during start-up. - The fault code can also be caused by the tachograph temporarily being supplied with too high a voltage.

System reaction

An error message is shown in the tachograph display.

How to fix

  1. Check the tachograph supply voltage.
  2. Check the cable harness.
  3. Check harness-to-harness connectors.
  4. Check whether other systems have generated a fault code for voltage supply.

This information is for guidance only. Always follow the manufacturer workshop manual and safety procedures; if in doubt, contact an authorised workshop.

Code 4 in other Scania systems

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