THM 4L60 (700-R4) -Converter Clutch Throttle Valve Bore Eliminated
CHANGE: Converter clutch throttle valve bore in valve body casting eliminated starting with the production of 1989 model THM 700-R4 (4L60).
REASON: No current production models using the converter clutch throttle valve, so the TCC bore is not needed.
Valve Body Casting - The new valve body casting will no longer have the TCC bore, and now contains a "Notch" in the worm track area allowing 2nd clutch oil into the XC Signal circuit (See Figure 1).
Not interchangeable with 1987 or earlier model transmissions, is compatible with 1988 models only.
THM 325/325-4L NO UPSHIFT, CUP PLUG MISSING
COMPLAINT: No upshift at any vehicle speed.
CAUSE: The cause may be the governor passage cup plug missing from the case (See Figure 1).
CORRECTION: Replace cup plug, available under OEM part number 8620318. This is a 3/8" diameter cup plug and may be available locally.