Reasons for the drop in speed when switching automatic transmission:
1. Transmission problems:
* Faulty automatic transmission control module (TCM)
* Low or poor quality transmission fluid
* Worn or damaged clutches and bands
* Clogged oil filter
2. Engine problems:
*Reduced power due to ignition, fuel or mechanical problems
*Heavy engine loads (such as towing or hill climbing)
3. Electrical problems:
* Broken wires or faulty electrical connections
* Faulty input or output shaft speed sensor
*Faulty throttle position sensor
4. Vacuum problems:
* Vacuum leakage from hoses or connections
* Faulty vacuum modulator
5. Other mechanical faults:
* Worn or seized drive shaft
* Damaged bearings
* Incorrect throttle position
Diagnostics:
To diagnose the cause of the drop in speed, the following actions are necessary:
* Attaches a trouble code scanner to search for transmission or engine related fault codes.
* Checking the level and condition of the transmission fluid.
* Checking the condition of clutches and bands when removing the automatic transmission pan.
* Measuring electrical continuity and voltage of automatic transmission sensors and wires.
* Check the operation of the speed and throttle position sensors.
* Inspect and replace damaged components or hoses.
Remedy:
Resolving the problem depends on the specific cause, but may include:
* Replacement of transmission fluid and filter
* Repair or replacement of faulty automatic transmission components
* Engine Troubleshooting
* Fix electrical problems
* Replacement of damaged mechanical components