Scania COO DTC 786 Switch, vehicle rear level adjustment

COO Coordinator · Scania · 3 variants

Code 786 (decimal). Some diagnostic tools show it in hexadecimal as 0312.

In short

All communication on the CAN bus for short-range radar on the left-hand side has been interrupted.

Variant 1: CAN bus for short-range radar, left-hand side

Applies to: COO10 (COO)

What does Scania COO fault code 786 mean?

All communication on the CAN bus for short-range radar on the left-hand side has been interrupted.

What causes Scania DTC 786?

- Open circuit in the CAN bus cable harness for short-range radar on the left-hand side. - Short circuit in the CAN bus cable harness for short-range radar on the left-hand side. - External damage or crush damage on the cable harness. - Internal fault in one of the units on the CAN bus for short-range radar on the left-hand side. - The connected control unit communicating at 250 kb/s.

How does the system react?

Multiple warnings are displayed in the instrument cluster.

What are the symptoms?

Functions that depend on information from CAN bus for short-range radar on the left-hand side will be impaired.

How to fix Scania COO fault code 786?

  1. Check that cable harness for CAN bus for short-range radar on the left-hand side is coming.
  2. Check that harness-to-harness connector for CAN bus for short-range radar on the left-hand side is coming.
  3. Disconnect the battery.
  4. Measure the resistance between the coordinator pin for CAN-high (pin C6) and CAN-low (pin C15).
  5. The resistance should be approx.
  6. 60 ohms.
  7. (Due to the two termination resistors connected in parallel.)
  8. Disconnect the battery.
  9. Measure the resistance between the coordinator pin for CAN-high and voltage supply.
  10. The resistance should be in the order of a Megaohm.
  11. Disconnect the battery.
  12. Measure the resistance between the coordinator pin for CAN-high and earth.
  13. The resistance should be in the order of a Megaohm.
  14. Disconnect the battery.
  15. Measure the resistance between the coordinator pin for CAN-low and voltage supply.
  16. The resistance should be in the order of a Megaohm.
  17. Disconnect the battery.
  18. Measure the resistance between the coordinator pin for CAN-low and earth.
  19. The resistance should be in the order of a Megaohm.
  20. Disconnect one unit from the CAN bus at a time to see if the fault disappears.

Variant 2: CAN bus for short-range radar, left-hand side, communication error

Applies to: COO11 (COO)

Detection

All communication on the CAN bus for short-range radar on the left-hand side has been interrupted.

Possible cause

- Open circuit in the CAN bus cable harness for short-range radar on the left-hand side. - Short circuit in the CAN bus cable harness for short-range radar on the left-hand side. - External damage or crush damage on the cable harness. - Internal fault in one of the units on the CAN bus for short-range radar on the left-hand side. - The connected control unit communicating at 250 kb/s.

Symptoms

Functions that depend on information from CAN bus for short-range radar on the left-hand side will be impaired.

How to fix

  1. Disconnect the power battery.
  2. Keep it disconnected during resistance measurements.
  3. Perform resistance measurement:
  4. Measure the resistance between CAN bus for short-range radar on the left-hand side CAN high (pin C6) and CAN low (pin C15) on the coordinator.
  5. The resistance should be approx.
  6. 60 ohms.
  7. (Due to 120 ohm termination resistance at each end of the CAN bus.)
  8. Measure the resistance between CAN bus for short-range radar on the left-hand side CAN high (pin C6) and the voltage supply.
  9. The resistance should be in the order of a Megaohm.
  10. Measure the resistance between CAN bus for short-range radar on the left-hand side CAN high (pin C6) and earth.
  11. The resistance should be in the order of a Megaohm.
  12. Measure the resistance between CAN bus for short-range radar on the left-hand side CAN low (pin C15) and the voltage supply.
  13. The resistance should be in the order of a Megaohm.
  14. Measure the resistance between CAN bus for short-range radar on the left-hand side CAN low (pin C15) and earth.
  15. The resistance should be in the order of a Megaohm.
  16. Check all control units on the CAN bus for short-range radar on the left-hand side.
  17. Check the harness-to-component connector, pin and cable harness.
  18. Check the harness-to-component connectors for all control units.
  19. Check if there is scarring or damaged, shorted or not connected pins.
  20. Disconnect one control unit at a time to see whether the fault disappears.

Variant 3

Applies to: COO7

Detection

The coordinator has interpreted the signal from the switch as prohibited.

Possible cause

The voltage of the signal is too high, which indicates a short-circuit.

System reaction

The switch cannot affect the vehicle level.

How to fix

  1. Check: Cable harness and harness-to-component connectors between the switch and coordinator.
  2. Switch for vehicle rear level adjustment.
  3. Check that the signal voltage between the switch and earth is greater than 4,800 mV.
  4. An unaffected switch should have a voltage between 3,140 and 2,559 mV.

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

Code 786 in other Scania systems

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