Possible reasons for the absence of 4th gear in a Suzuki Escudo automatic transmission:
1. Mechanical problems:
*Damage to planetary gear associated with 4th gear
* Worn torque converter assembly
*Damage to internal drive shaft
* Failure of the gear shift position sensor
2. Electrical problems:
* Malfunction of the electronic control unit (ECU) of the automatic transmission
* Damage to wiring or connectors
* Gear selector malfunction
3. Hydraulic problems:
*Low transmission fluid level
* Clogged or leaking hydraulic circuit
* Shift valve malfunction
* Wear or contamination of the automatic transmission filter
Diagnosis and troubleshooting:
* Checking the level and condition of the transmission fluid: Add fluid if necessary and check its condition for any darkening or burning smell.
* Reading Trouble Codes Using an OBDII Scanner: This can reveal any electrical or electronic problems.
* Visual Inspection and Leak Check: Look for signs of damage or leaks in the transmission, driveline or wiring.
*Checking transmission fluid pressure: The pressure must correspond to the parameters specified by the manufacturer.
* Diagnosis by a professional mechanic: If the above steps do not reveal the cause, contact a professional for further diagnosis and repair.
Note: Do not attempt to fix automatic transmission problems yourself unless you are qualified to do so. Automatic transmission malfunctions can be complex and require qualified repairs.