G 20 Van V6-262 4.3L VIN Z (1993)
Transmission Speed Sensor: All Technical Service Bulletins
A/T - No Upshift/Stuck In First/No Codes/Exterior Leaks
Number: 93-147-7A
Section: 7A
Date: MARCH 1993
Corporate Bulletin No.: 377118
ASE No.: A2
Subject:
NO UPSHIFT/STUCK IN FIRST/NO CODES/EXTERIOR LEAKS
Model and Year:
1991-93 C/K, R/V, P, G TRUCKS WITH 4L80-E/4L80-EHD AUTOMATIC TRANSMISSION
Some HYDRA-MATIC 4L80-E/4L80-EHD transmissions may experience a no upshift, stuck in first with no Diagnostic Trouble Codes (DTC) stored.
CAUSE:
Input/output speed sensor malfunction, or leaking (wicking) fluid through the speed sensor connector (internal and/or external). If the input speed sensor
is not functioning correctly, the output speed sensor is not used for reference by the PCM/TCM and an upshift cannot occur.
CORRECTION:
Diagnose per the input speed sensor circuit check as outlined in Section 7A of the appropriate service manual. Replace the speed sensor if necessary.
DATE OF PRODUCTION:
(Figure 1) Starting January 15, 1993 (Julian Date 015) all 1993 HYDRA-MATIC 4L80-E/4L80-EHD models will have the new speed sensor assemblies.
SERVICE PARTS INFORMATION:
Part #
Name
8685042
Speed Sensor Assembly
Labor Codes:
Replace input sensor K6311 or output sensor K6312.
Parts are expected to be available on March 22, 1993.
