K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
Planetary Gears: Customer Interest
A/T - 4L60 Stuck In First Gear
GMC NUMBER:
91-7A-125
GROUP:
7A Automatic Transmission
DATE:
July, 1991
CORPORATE
NUMBER:
177113R
SUBJECT:
TRANSMISSION STUCK IN FIRST GEAR (INSTALL CARRIER TO OUTPUT SHAFT RETAINING RING)
MODELS:
1982-91 S/T, C/K, R/V, M, L, G, LIGHT TRUCKS, AND VANS
Some HYDRA-MATIC 4L60/7OO-R4 transmissions may experience a "no upshift" or "stuck in first gear" condition. This may be caused by the input
carrier to output shaft retaining ring coming unseated, or retaining ring omitted during assembly. This can allow the output shaft to move slightly, and
cause wear on the governor gear (the governor gear ON THE GOVERNOR, not the governor drive gear on the output shaft). The governor gear wear
may be described as an "apple cored" condition. If the governor gear is worn, the transmission cannot upshift out of first gear.
Figure 1
Service Information:
Remove the governor and inspect the governor gear. If it is "apple cored", disassemble the transmission and look for the presence of the input carrier to
output shaft retaining ring. (See Figure 1.)
^
If the retaining ring is missing, replace it, but make sure the original retaining ring is not broken and stuck inside the transmission.
^
If the retaining ring has become unseated, replace the retaining, ring with a new one since the original has probably been overexpanded.
When installing a new retaining ring, be careful not to overexpand the retaining ring.
Service Parts Information:
The input carrier to output shaft retaining ring is available in several packages through GMSPO. It is included in the snap ring package, overhaul repair
components package, and overhaul seals and gasket package.
Service Manual References:
Reference the Automatic Transmission Unit Repair Section of the appropriate service manual for retaining ring installation information.
