Communication with the SCR control unit
Clear the fault code memory and try to start the engine.Check fuses.If there are SCR system fault codes present, troubleshoot these first.Switch the power off and on a few times. Fault codes which were not generated in the engine control unit could be present in the SCR control unit because this fault code is active.If no fault code indicating that the SCR system is deactivated is present, check the electrical cables and clean the connectors. Check that the fuses for the SCR system are intact.Also check that both control units are receiving 15 voltage at the same time.Check fuses.If neither of the above helps, renew the SCR control unit. If this does not help, renew the engine control unit.Inactive fault codes are seldom the main cause of faults. Always troubleshoot active fault codes first.When troubleshooting inactive fault codes: Check that they have not been generated during a workshop visit or when switching off the main power switch by going to More information and checking whether the vehicle speed was 0 or 15 and the engine speed was 0 when the fault code was generated.Also check whether the fault code has been generated by low voltage by checking whether the voltage was below 22 volts when it was generated.Proceed as follows to verify that the fault has been rectified:Switch off the 15 voltage, wait for at least 90 seconds and switch on the 15 voltage again.If the fault has been rectified, the fault code becomes inactive. Clear the fault code.Switch the 15 voltage off and on three times in succession at 10 second intervals to extinguish the warning lamp.
What you'll see
No driver-visible symptom recorded.
System reaction
No system-reaction text recorded.
Diagnostic depth
The engine control module has no CAN message from the SCR system.
If the fault code is generated frequently, this is probably due to a fault in the cable harness or connectors.Communication between the engine control unit and the SCR control unit has been interrupted.In the case of some faults, the SCR control unit deactivates the SCR system to prevent damage to the SCR system. This means that communication between the SCR control unit and the engine control unit is broken.If this fault code is generated once and there are no other SCR system fault codes, this may be because the voltage to the SCR control unit has been interrupted while the engine control unit has been supplied with voltage.The SCR control unit in the pump may be defective.If fault code 5688 has been generated at the same time, there is probably a fault in the engine control unit.If this fault code has been generated, but not fault code 5688, then there is probably a fault in the electrical cables.If fault code 5657 or 8263 has been generated at the same time, start by troubleshooting from them initially.The connector has been disconnected with the power on or when reprogramming the control unit at the workshop.Low battery voltage.