Firebird V8-305 5.0L VIN F FI (1987)
Engine Speed Governor: Customer Interest
A/T - THM 440-T4 Second Gear Starts
Number
87-7-33
Date
7/87
Subject:
SECOND GEAR STARTS
1984-87 6000 AND 1987 BONNEVILLE MODELS EQUIPPED WITH THM 440-T4 (ME9)
Figure 1 - THM 440-T4 Transaxle Identification Information
TRANSAXLE MODELS:
All
BULLETIN COVERS:
A 1984-87 vehicle equipped with a THM 440-T4 (Figure 1) may start out in 2nd gear instead of 1st gear.. This condition could occur intermittently or all
the time.
Figure 2
SERVICE ACTION:
High line pressure could be a cause by holding too much governor pressure and not allowing the 1-2 shift valve to downshift. Check line pressure and
governor pressure. Governor pressure should be below 3.0 psi at 0 mph.
If governor pressure is okay, the 1-2 shift valve (331) may be stuck in the upshifted position. Remove the control valve assembly and check for a sticking
1-2 shift valve (331), 1-2 throttle valve (332), or the 1-2 throttle valve spring (333) caused by the 1-2 throttle valve bushing retainer (390) pushed in too
