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Troubleshooting Charts For Allison Transmissions AT / MT (B) / HT / V

The troubleshooting information contained in the following charts outlines the possible causes of transmission conditions and their remedies. Several possible causes are indicated; numbered items indicate suggested remedies for the causes. For Sales and Service Call America's #1 Supplier of OEM Allison Transmission Parts and Authorized Allison Dealer; TransDiesel Transmission Call us: 1-407-295-1221

O - CLUTCH(ES) SLIPPING - MT(B) 644/647, 654CR* Condition Probable Causes Suggested Remedies Slipping in First and Reverse Ranges Only (MT(B) 644/647) 1. First clutch defective. 1. Overhaul clutch and replace piston seals. Slipping in First and Reverse Ranges (MT 654CR) 2. Low clutch defective. 2. Overhaul clutch and replace piston seals. Slipping in Second or Third Ranges Only (MT(B) 644/647) 3. Clutch for particular range 3. Overhaul clutch and replace piston seals. Slipping in Third or Fourth Ranges Only (MT 654CR) 4. Clutch for particular range defective. 4. Overhaul clutch and replace piston seals. Slipping in Fourth and Reverse Ranges Only (MT(B) 644/647) 5. Fourth clutch defective. 5. Overhaul clutch and replace piston sealrings. Slipping in Fifth and Reverse Ranges Only (MT(B) 654 CR) 6. Fifth clutch defective. 6. Overhaul clutch and replace piston sealrings. 7. Sealrings on center support hub worn or broken. 7. Inspect valve for contamination and proper operation. Slipping in First Range Only (MT(B) 644/647) 8. First clutch defective. 8. Overhaul clutch and replace piston sealrings. Slipping in Second Range Only (MT(B) 654CR) 9. Second clutch defective. 9. Overhaul clutch and replace piston sealrings. Slipping in All Forward Ranges 10. Centrifugal check valve stuck open. 10. Inspect valve for contamination and proper operation. * NOTE: If unit is modified for split shaft PTO, all external circuitry must be removed before troubleshooting.