A/T - Fluid Leaks Through Connector

Group Ref.: Transmission

Bulletin No.: 377129

Date: November, 1993

SUBJECT:
FLUID LEAKS AT TRANSMISSION PASS-THROUGH CONNECTOR
(NEW WIRE HARNESS AND SERVICE KIT)

MODELS:
1991-93 CHEVROLET & GMC C/K, R/V AND P TRUCKS, G-VAN AND ISUZU (EQUIPPED WITH HYDRA-MATIC 4L80-E/4L80-EHD TRANSMISSION)

CONDITION:

Some vehicles may exhibit a fluid leak out the transmission pass-through connector causing material degradation on vehicle side connector and wiring which may lead to erratic transmission operation.

CAUSE:

"Wicking" of fluid between wire and insulation through the pins and into the connector interface and ultimately to the vehicle side wiring.





CORRECTION: (Figure 2)

Replace the wire harness assembly per your transmission service manual and install this service package per instruction sheets.





DATE OF PRODUCTION: (Figure 1)

Starting May 5, 1993 (Julian date 125), all 1993 HYDRA-MATIC 4L80-E/4L80-EHD models will have the new wiring harness.





SERVICE PROCEDURE: (Figure 3)

Refer to the appropriate Service Manual Section for proper replacement procedures for the transmission wiring harness.

When installing a S.R.T.A. unit or replacing a wiring harness on an assembly built prior to May 5, 1993 (Julian Date 125), it will be necessary to install the service jumper harness included in the service package. Installation instructions are included in this bulletin and in the service package.

WARRANTY INFORMATION:





For vehicles repaired under warranty, use: (see illustration)





SERVICE PARTS INFORMATION:

Parts are currently available from GMSPO.

INSTRUCTIONS:

Wiring Harness Assembly

The electrical wiring harness is updated with an extra length on one of the conduits leading to the pressure control solenoid on the control valve assembly.

Whenever servicing a 4L80-E/4L80-EHD transmission prior to 1994 Model Year and the electrical wiring harness is being installed, the extra slack in wire length for the pressure control solenoid (PCS) can be taken up by twisting the conduit one to two turns with the conduit that leads to the pulse width modulated (PWM) solenoid, then the PWM and the PCS conduits can be connected. The twisted wires will take up the extra slack and will prevent any loose wire from becoming pinched or crushed when the oil pan is installed.