D21 Hardbody 4WD V6-2960cc 3.0L SOHC MFI (VG30E) (1991)
Control Valve Assembly: Customer Interest
A/T - 1st To 2nd Gear Shift Shock Modification
Classification:
Section:
Automatic
A/T91-004
Transmission
Reference:
TECHNICAL BULLETIN NTB91-062
Models:
1990-91 Truck
Date:
June 13, 1991
TRUCK A/T MODIFICATION FOR SHIFT SHOCK
APPLIED MODEL:
1990-91 Truck (D21) with RL4R01A Transmission
APPLIED UNIT DATE:
January 1, 1991
APPLIED UNIT NUMBER: 0Z55915
SERVICE INFORMATION
Some 1990-91 Trucks with the RL4R01A automatic transmission, built before the applied date, may exhibit D1 - D2 shift shock. This incident may be
caused by a worn orifice check valve. When excessive wear occurs to the orifice check valve, it may break into pieces and collect in the 1 - 2
accumulator valve. The orifice check valve and spring have been eliminated on vehicles produced after the applied date. The control valve part number
has not been changed.
SERVICE PROCEDURE
Remove the orifice check valve and orifice check spring. Inspect the orifice check valve for wear or damage (see illustration). If the check valve is
broken, inspect the 1 - 2 accumulator for pieces of the check valve. Clean the accumulator as necessary.
The check valve and orifice check spring should be discarded even if there is no wear or damage. Removal of this part will not affect the operation of the
transmission.