C 2500 Truck 2WD V8-454 7.4L VIN J SFI (1996)
Control Module: Customer Interest
A/T - Upshift Flare/No 3rd or 4th/Launch Shudder
File In Section: 07 - Transmission/Transaxle
Bulletin No.: 00-07-30-026
Date: December 2000
TECHNICAL
Subject:
Automatic Transmission 1-2 and/or 2-3 Upshift Slip/Flare, No 3rd or 4th gear, Launch Shudder (Revise VCM Wiring)
Models:
1996 Chevrolet and GMC C/K, S/T, M/L, G1, G2, P3 Models
1996 Oldsmobile Bravada
with VCM and 4L60-E (M30) or 4L80-E (MT1) Automatic Transmission
This bulletin is being reissued to ensure that correct procedures are followed for this condition. Please discard Corporate Bulletin Number 66-71-03A
(Section 7 - Automatic Transmission).
When performing a transmission replacement labor operation K7000 on these vehicles with a 4L60-E or 4L80-E, you must include front chassis wire
repair labor operation N6112. Inspect the VCM to verify the latest part number revision (16244210).
Condition
Some owners may comment that the automatic transmission has either a slip or flare on the 1-2 and/or 2-3 upshift, or no 3rd or 4th gear, or launch
shudder. Upon investigation, the technician may find a DTC P1870 stored in the VCM.
Cause
A poor internal ground between the two circuit boards of the VCM may cause the VCM to command erratic line pressure at the pressure control (PC)
solenoid valve.
Correction
Using harness jumper wire and instruction kit, P/N 12167310, revise the wiring harness at the VCM connector. Corrections were made to the VCM
beginning 2/14/96. The corrected VCMs are identified with service number 16244210 on the VCM identification label.
Procedure
The following is a summary of the instructions included with the service kit:
1.
Remove the negative terminal from the battery.
2.
Move the wire located at connector J3 (WHITE/GREY/CLEAR), pin 18 to connector J1 (BLUE), pin 23.
3.
Install the jumper wire between connector J2 (RED), pin 26 and connector J3 (WHITE/GREY/CLEAR), pin 18.
4.
Install the tag included in the kit around the. VCM wiring harness. This tag notes that the wiring harness has been modified.
5.
Reconnect the negative battery terminal.
Road test to verify that the condition has been corrected. If any of the following conditions are noted, the transmission should be repaired or replaced
using the most cost effective method. Canadian dealers should repair the transmission.
^
Transmission fluid oxidation or excessive sediment.
^
Transmission slip or flare after this service fix is performed.
^
DTC P1870 is stored on a 4L60-E (M30).
The following tools are available from Kent-Moore (1-800-345-2233) for use in removing and relocating the VCM wires:
