A/T - Elimination of 4-3 Downshift Switch
Number: 84-144Section: 7A (VIIc)
Date: June, 1984
Subject: ELIMINATION OF 4-3 DOWNSHIFT SWITCH TO REDUCE POSSIBLE 4-3 DOWNSHIFT FLARE
Model and Year: 1984 THM 700-R4 (YA AND YW)
TO: ALL CHEVROLET DEALERS
FIGURE 1 - 4-3 DOWNSHIFT SWITCH WIRING DIAGRAM BEGINNING JULIAN DATE 065, 1984:
Beginning March 5, 1984 (Julian Date 065), 1984 models YA and YW THM 700-R4 transmissions were built with a new solenoid and "O" ring assembly which has a 3 wire harness (P/N 8654129) which is not connected to the 4-3 downshift switch (Figure 1). This is done to reduce a possible 4-3 downshift flare.
The 4-3 downshift switch will remain a part of the control valve body assembly for the remainder of 1984 production for service reasons..
FIGURE 2 - 4-3 DOWNSHIFT SWITCH WIRING DIAGRAM PRIOR TO JULIAN DATE 065, 1984:
Models built prior to Julian Date 065 were built with a solenoid and "O" ring assembly that has a 4 wire harness which uses the 4-3 downshift switch (Figure 2).
FIGURE 1 - 4-3 DOWNSHIFT SWITCH WIRING DIAGRAM BEGINNING JULIAN DATE 065, 1984:
The 4 wire harness is superseded by the 3 wire harness (P/N 8654129). When servicing the 4 wire harness, replace it with the 3 wire harness and bypass the 4-3 downshift switch as shown in Figure 1.