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.
PARTS AFFECTED:
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).
INTERCHANGEABILITY:
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.
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