Automatic Transmission

Symptom Troubleshooting Index (cont'd)

 14-18  

Symptom Probable cause(s) Notes
Harsh downshift:

2nd to 1st gear
  1. A/T clutch pressure control solenoid valve A defective
  2. CPC valve defective
  3. 2nd accumulator defective
  4. CPB valve defective
  5. Foreign material in 2nd exhaust orifice
  6. Mainshaft speed sensor defective
  7. Countershaft speed sensor defective
  • Check the indicator light indication and check for loose connectors. Inspect the A/T clutch pressure control solenoid valve filter/gasket for wear and damage. If the A/T clutch pressure control solenoid valve is stuck, inspect the CPC valve.
  • Check the 2nd clutch pressure.
  • Check the mainshaft speed sensor installation.
  • Check the countershaft speed sensor installation.
Harsh downshift:

3rd to 2nd gear
  1. 2nd clutch defective
  2. A/T clutch pressure control solenoid valve A defective
  3. CPC valve defective
  4. 3rd accumulator defective
  5. Foreign material in separator plate orifice
  6. CPB valve defective
  7. Foreign material in 3rd exhaust orifice
  8. Mainshaft speed sensor defective
  9. Countershaft speed sensor defective
  10. 3rd sub accumulator defective
  • Inspect the clutch piston, clutch piston check valve and O-rings. Check the spring retainer for wear and damage. Inspect the clutch end plate-to-top disc clearance. If the clearance is out of tolerance, inspect the clutch discs and plates for wear and damage. If the discs and plates are worn or damaged, replace them as a set. If they are OK, adjust the clearance with the clutch end plate.
  • Check the 2nd clutch pressure.
  • Check the indicator light indication and check for loose connectors. Inspect the A/T clutch pressure control solenoid valve filter/gasket for wear and damage. If the A/T clutch pressure control solenoid valve is stuck, inspect the CPC valve.
  • Check the mainshaft speed sensor installation.
  • Check the countershaft speed sensor installation.
Harsh downshift:

4th to 3rd gear
  1. 3rd clutch defective
  2. A/T clutch pressure control solenoid valve A defective
  3. CPC valve defective
  4. 4th accumulator defective
  5. Foreign material in separator plate orifice
  6. CPB valve defective
  7. Foreign material in 4th exhaust orifice
  8. Mainshaft speed sensor defective
  9. Countershaft speed sensor defective
  • Inspect the clutch piston, clutch piston check valve and O-rings. Check the spring retainer for wear and damage. Inspect the clutch end plate-to-top disc clearance. If the clearance is out of tolerance, inspect the clutch discs and plates for wear and damage. If the discs and plates are worn or damaged, replace them as a set. If they are OK, adjust the clearance with the clutch end plate.
  • Check the 3rd clutch pressure.
  • Check the indicator light indication and check for loose connectors. Inspect the A/T clutch pressure control solenoid valve filter/gasket for wear and damage. If the A/T clutch pressure control solenoid valve is stuck, inspect the CPC valve.
  • Check the mainshaft speed sensor installation.
  • Check the countershaft speed sensor installation.