Possible reasons why your Grand Cherokee automatic transmission only goes backwards:
*Transmission fault: An internal damaged component, such as a friction plate or drum, may prevent the transmission from engaging forward gears.
* Faulty hydraulic unit: The hydraulic unit is responsible for regulating the flow of fluid in the transmission, and its failure can lead to problems with shifting gears.
* Faulty Transmission Control Module (TCM): The TCM controls the operation of the transmission and a malfunction can result in malfunction.
* Low automatic transmission fluid pressure: Low or dirty automatic transmission fluid can cause insufficient pressure in the system, which can lead to problems with shifting.
* Faulty gear selector: A faulty gear selector may not accurately indicate the selected gear, resulting in difficulty shifting into forward gears.
*Locked Differential: A locked differential can prevent one wheel from turning, which can cause the vehicle to only drive backwards.
Troubleshooting:
1. Check the level and condition of the automatic transmission fluid: Make sure that the fluid level is correct and that it is clean. Replace fluid and filter if necessary.
2. Scan for trouble codes: Use a diagnostic scanner to check for any trouble codes. They may indicate a faulty component in the transmission system.
3. Check the hydraulic block: Check the hydraulic block for leaks or damage. Replace it if necessary.
4. Check TCM: Check the TCM for damage or corrosion. Replace it if necessary.
5. Check the gear selector: Make sure the gear selector is in good working order and accurately points to the selected gear.
6. Check the differential: Check the differential for locking. Repair or replace it if necessary.
7. Transmission Repair or Replacement: If other troubleshooting options are unsuccessful, the transmission may need to be repaired or replaced.
Precautions:
*Do not attempt to drive the vehicle in this condition as further damage may result.
*Consult a qualified mechanic to diagnose and repair the problem.
*Be prepared that repairs can be expensive, especially if the transmission requires replacement.