EXPERTEC TSB (93-7A-58)

EXPERTEC TSB

TECHNICAL SERVICE BULLETIN

NO UPSHIFT/STUCK IN FIRST/NO - CODES/EXTERIOR LEAKS

Model(s): 1991-93 GMC C/K, RIV, P, and G Vehicles with 4L80-E/4L80-EHD Transmissions Condition

Bulletin No.: GMC 93-7A-58

Date: 03/17/1993

SERVICE INFORMATION

Some 1991-93 C/K, R/V, P, and G Vehicles With 4L8O-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

Fig 1 )

Starting January 15, 1993 (Julian Date 015) all 1993 C/K, R/V, P, and G Vehicles With 4L80-E/4L80-EHD transmissions will have the new speed sensor assemblies.

BULLETIN ILLUSTRATION LIST

SERVICE PARTS INFORMATION

Part #	Description
8685042	Speed Sensor Assembly

WARRANTY INFORMATION

For vehicles repaired under warranty, use:

Labor Codes: Replace input sensor K6311 or output sensor K6312.

Parts are expected to be available on March 22, 1993.