Troubleshooting problems when shifting gears in an automatic transmission
Common reasons:
*Low transmission fluid level
* Worn or damaged transmission parts
* Faulty Transmission Control System (TCM)
*Sensors are faulty or not calibrated
Symptoms:
* Slipping or delay when shifting gears
*Hard shifting or bumping
* Strange noises when shifting gears
* The gearbox goes into emergency mode
*No transmission
Troubleshooting steps:
1. Check the transmission fluid level:
* Make sure the car is parked on a level surface.
* Remove the oil dipstick and wipe it with a clean cloth.
* Insert the dipstick back and remove it again.
* Check the fluid level and make sure it is between the “min” and “max” marks.
*If the fluid level is low, add the recommended fluid and check again.
2. Scan the system for fault codes:
* Connect the OBD-II scanner to the vehicle’s diagnostic port.
*Run a scan and write down any trouble codes that appear.
* Investigate trouble codes to determine possible causes of shifting problems.
3. Check the transmission fluid pressure:
* Connect the transmission fluid pressure gauge to the appropriate port on the transmission.
* Start the engine and let it idle.
* Read the transmission fluid pressure readings and compare them with the specified values.
*Low or high transmission fluid pressure may indicate a problem with the transmission system.
4. Check the mechanical components of the transmission:
* Check the condition of the solenoids, gear shift mechanism, clutch and belts.
* Look for signs of wear, damage or defects.
* Replace any faulty components as needed.
5. TCM Reprogramming:
*If other troubleshooting steps do not resolve the shifting problem, the TCM may need to be reprogrammed.
* Reprogramming updates the TCM software and calibrates it to work optimally with other transmission components.
6. Additional checks:
* Check the transmission system wires and connections for damage or corrosion.
* Make sure the transmission filter is clean and not clogged.
* Inspect the transmission pan gasket or seal for leaks or damage.
Note: Diagnostics and repair of automatic transmissions require professional knowledge and equipment. It is recommended that you contact a qualified mechanic for proper troubleshooting and repairs.