Scania COO DTC 839 CAN communication with switch module

COO Coordinator · Scania · 5 variants

Code 839 (decimal). Some diagnostic tools show it in hexadecimal as 0347.

In short

Fault in communication with the switch module.

Variant 1

Applies to: COO10 (COO)

What does Scania COO fault code 839 mean?

Fault in communication with the switch module.

What causes Scania DTC 839?

- The switch module is misconfigured as regards CAN address, position or type (6 or 10 positions). - The switch module is not connected to the switch module CAN network, or there is a break in the cable harness on the switch module sub data bus. - Fault in the wake-up signal or voltage supply. - Defective switch module.

How does the system react?

Yellow warning indication of a coordinator fault is displayed.

What are the symptoms?

Degradation of functions connected to the switch module.

How to fix Scania COO fault code 839?

  1. Start the Configuration of switch modules wizard and action any switch module faults.
  2. Switch modules with faults are marked in red and a symbol in the configuration tool.
  3. Check the connections and cable harness for breaks in the cable harness on the switch module sub data bus.
  4. Check the connections and cable harness for a short circuit on the wake-up signal and switch module voltage supply.
  5. Check the resistance on the switch module sub data bus:
  6. Measure the resistance between CAN high and CAN low of the switch module in question with the battery disconnected.
  7. The resistance should be approx.
  8. 60 ohms.
  9. Measure the resistance between CAN high of the switch module in question and CAN high of the other units on the switch module sub data bus, with the battery disconnected.
  10. The resistance should be approx.
  11. 0 ohms.
  12. Measure the resistance between CAN low of the switch module in question and CAN low of the other units on the switch module sub data bus, with the battery disconnected.
  13. The resistance should be approx.
  14. 0 ohms.
  15. If the fault cannot be rectified, renew the switch module and configure the new one using the Configuration of switch modules wizard.

Variant 2

Applies to: COO11 (COO)

Detection

Fault in communication with the switch module.

Possible cause

- The switch module is misconfigured as regards CAN address, position or type (6 or 10 positions). - The switch module is not connected to the switch module CAN network, or there is a break in the cable harness on the switch module sub data bus. - Fault in the wake-up signal or voltage supply. - Defective switch module.

Symptoms

Degradation of functions connected to the switch module.

How to fix

  1. Disconnect one switch module at a time from the switch CAN bus to see if the fault disappears.
  2. Check the harness-to-component connector to the button panel.
  3. Check the cable harness between the button panel and the coordinator.
  4. Check that no pins in the harness-to-component connectors are eroded, broken, shortened or disconnected.
  5. If the fault persists, check the switch module and its function.
  6. Check that the button panel has been configured correctly.

Variant 3

Applies to: COO8 (COO)

Detection

Fault in communication with the switch module.

Possible cause

- The switch module is misconfigured as regards CAN address, position or type (6 or 10 positions). - The switch module is not connected to the switch module CAN network, or there is a break in the cable harness on the switch module sub data bus. - Fault in the wake-up signal or voltage supply. - Defective switch module.

Symptoms

Degradation of functions connected to the switch module.

How to fix

  1. Start the Configuration of switch modules wizard and action any switch module faults.
  2. Switch modules with faults are marked in red and a symbol in the configuration tool.
  3. Check the connections and cable harness for breaks in the cable harness on the switch module sub data bus.
  4. Check the connections and cable harness for a short circuit on the wake-up signal and switch module voltage supply.
  5. Check the resistance on the switch module sub data bus:
  6. Measure the resistance between CAN high and CAN low of the switch module in question with the battery disconnected.
  7. The resistance should be approx.
  8. 60 ohms.
  9. Measure the resistance between CAN high of the switch module in question and CAN high of the other units on the switch module sub data bus, with the battery disconnected.
  10. The resistance should be approx.
  11. 0 ohms.
  12. Measure the resistance between CAN low of the switch module in question and CAN low of the other units on the switch module sub data bus, with the battery disconnected.
  13. The resistance should be approx.
  14. 0 ohms.
  15. If the fault cannot be rectified, renew the switch module and configure the new one using the Configuration of switch modules wizard.

Variant 4

Applies to: COO9 (COO)

Detection

Fault in communication with the switch module.

Possible cause

The cause can be one of the following: - Switch module configured incorrectly in relation to CAN address, position or type (6 or 10 positions). - The switch module is not connected to the switch module CAN network or open circuit in the cable harness on the switch module sub data bus. - Fault in the wake-up signal or supply voltage. - Defective switch module.

Symptoms

Degradation of functions connected to the switch module.

How to fix

  1. Start the Configuration of switch modules wizard and rectify any switch module faults.
  2. Switch modules with faults are marked in red and a symbol in the configuration tool.
  3. Check the connections and cable harness for open circuits in the cable harness on the switch module sub data bus.
  4. Check the connections and cable harness for a short circuit on the wake-up signal and switch module voltage supply.
  5. Check the resistance on the switch module sub data bus:
  6. Measure the resistance between CAN high and CAN low of the switch module concerned with the battery disconnected.
  7. Resistance should be around 60 ohms.
  8. Measure the resistance between CAN high of the switch module concerned and CAN high of the other units on the switch module sub data bus, with the battery disconnected.
  9. Resistance should be around 0 ohms
  10. Measure the resistance between CAN low of the switch module concerned and CAN low of the other units on the switch module sub data bus, with the battery disconnected.
  11. Resistance should be around 0 ohms.
  12. If the fault cannot be rectified, renew the switch module and configure the new one with the Configuration of switch modules wizard.

Variant 5

Applies to: COO8

Detection

Fault in communication with the switch module.

Possible cause

The cause can be one of the following: - Switch module configured incorrectly in relation to CAN address, position or type (6 or 10 positions). - The switch module is not connected to the switch module CAN network or open circuit in the cable harness on the switch module sub data bus. - Fault in the wake-up signal or supply voltage. - Defective switch module.

System reaction

- Degradation of functions connected to the switch module. - The warning is displayed in the instrument cluster (depending on configuration).

How to fix

  1. Start the Configuration of switch modules wizard and rectify the switch module fault.
  2. Switch modules with faults are marked in red and a symbol in the configuration tool.
  3. Check the connections and cable harness for open circuits in the cable harness on the switch module sub data bus.
  4. Check the connections and cable harness for a short circuit on the wake-up signal and switch module voltage supply.
  5. Check the resistance on the switch module sub data bus:
  6. Measure the resistance between CAN high and CAN low of the switch module in question with the battery disconnected.
  7. Resistance should be around 60 ohms.
  8. Measure the resistance between CAN high of the switch module in question and CAN high of the other units on the switch module sub data bus, with the battery disconnected.
  9. Resistance should be around 0 ohm.
  10. Measure the resistance between CAN low of the switch module in question and CAN low of the other units on the switch module sub data bus, with the battery disconnected.
  11. Resistance should be around 0 ohm.
  12. If the fault cannot be rectified, renew the switch module and configure the new one using the Configuration of switch modules wizard.

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

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