Volvo VNL Semi Truck & Volvo D13, Cummins ISX etc. Engine FAQs

1. Faulty clutch actuator The clutch actuator is an air or electrically operated component that controls the engagement and disengagement of the clutch. If it is not functioning properly, it can cause the gears to slip. To fix this issue, the faulty clutch actuator will need to be identified and replaced. 2. Clutch actuator solenoid The clutch actuator solenoid is responsible for controlling the flow of hydraulic fluid to the clutch actuator. If it is faulty, it can cause the gears to slip. To fix this issue, the faulty clutch actuator solenoid will need to be identified and replaced. 3. Faulty TECU gearbox control unit The TECU (Transmission Electronic Control Unit) gearbox control unit controls the flow of hydraulic fluid to the clutch actuator and other components in the transmission. If it is faulty, it can cause the gears to slip. To fix this issue, the faulty TECU gearbox control unit will need to be identified and replaced. 4. Faulty TECU The TECU is responsible for controlling the transmission and ensuring that it is shifting properly. If it is faulty, it can cause the gears to slip. To fix this issue, the faulty TECU will need to be identified and replaced. It is important to properly diagnose the cause of gear slipping before attempting to repair it. Replacing the wrong component can lead to further problems and costly repairs. If you are experiencing gear slipping on your Volvo I-Shift transmission and are unsure of the cause, it is best to consult a professional mechanic or Volvo dealership for assistance.

Steps to Troubleshoot and Repair Derate Mode Issues: Check for fault codes: Using a diagnostic scan tool, check for any fault codes that may be causing the derate mode. These codes can help to identify the specific issue with the engine. Perform a visual inspection: Look for any visible problems that may be causing the derate mode, such as damaged wiring or components. Check the intake air system: Make sure that the intake air system does not have any leaks and is not blocked or restricted. A leak or restriction in the intake air system can cause the engine to go into derate mode. Check the exhaust system: Make sure that the exhaust system is not blocked, restricted or having any leaks on gaskets or clamps etc.. A restriction or leak in the exhaust system can cause the engine to go into derate mode. Check the fuel system: Make sure that the fuel system is functioning properly and that there are no issues with the fuel filters or fuel lines. Check the EGR system: Make sure that the EGR (exhaust gas recirculation) system is functioning properly. Issues with the EGR system can cause the engine to go into derate mode. Check the turbocharger: Make sure that the turbocharger is functioning properly and that there are no issues with the VGT (variable geometry turbo) or actuator. Check the NOx sensors: Make sure that the NOx (nitrogen oxide) sensors are functioning properly and that there are no issues with the wiring or connections. Perform a parked regen: If all other checks have been completed and the issue with the derate mode persists, perform a parked regeneration (regen) and monitor the parameters to see if any of them do not meet the standards. This should help bring the root cause of the derate to the surface (the fault code should appear). Or the ECM / ACM may recognize that there are no current issues and it may remove the derate. Perform an SCR efficiency test: If the regen passes and no fault codes are present, perform an SCR (selective catalytic reduction) efficiency test and again monitor the parameters.This should help bring the root cause of the derate to the surface (the fault code should appear). Or the ECM / ACM may recognize that there are no current issues and it may remove the derate.

Symptoms of a Failing VGT or Actuator: If the VGT or actuator is failing, you may notice the following symptoms: Decreased engine performance and power Abnormally fast rise in soot level Erratic engine RPM fluctuation Engine may shut off or bog down if the VGT or actuator get stuck in the closed position Decreased turbo boost pressure Increased exhaust gas temperature (EGT) Increased fuel consumption Increased black smoke from the exhaust