Service Information
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1999 Pontiac Grand Prix | Grand Prix (VIN W) Service Manual | Transmission/Transaxle | Automatic Transaxle - 4T65-E | Diagnostic Information and Procedures | Document ID: 54887
Slipping or No Third Gear
Slipping or No Third Gear

Checks


Cause

DEFINITION: A large engine RPM increase is noted in third gear, Drive range, with little or no vehicle forward speed increase. First, second, and fourth gear operation are normal. Shifts into third gear are soft or do not occur. Third gear ratio is 1.000:1.

Automatic Transmission Fluid Level


Low fluid level

Transmission Main Line Pressure


Low transmission main line pressure

Oil Filter Assembly

• The oil filter assembly (100) is missing, plugged, or damaged.
• The oil filter seal assembly (101) is missing or is damaged.

Control Valve Body Assembly

• The 2-3 shift valve (357) or the 3-2 manual downshift valve (356) is stuck or binding.
• Debris is found in the passages of the control valve body (301) or of the control valve body spacer plate and gasket assembly (396)
• The #4 or the #9 ball check valve is missing or mislocated.

Driven Sprocket Support Assembly


A plugged third clutch oil passage in the driven sprocket support assembly (609)

Third Clutch Assembly

• Input clutch housing oil seal rings (628) are missing or damaged.
• The third clutch ball check valve assembly (724) is missing or damaged.
• The third clutch piston (642) is damaged.
• The third clutch piston inner seal (641) is missing or damaged.
• The third clutch plates (645-648) are worn or misassembled.

Third Clutch Sprag Assembly

• The sprag (720) was misassembled or backwards on the inner race (661).
• A damaged third clutch sprag assembly (653, 661, 719-721)
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