EXPERTEC TSB (93-36-7A)

EXPERTEC TSB

TECHNICAL SERVICE BULLETIN

SCAN TOOL LOSS OF - COMMUNICATION (INFORMATION)

Model(s): 1993 Chevrolet C/K,S/T Trucks And ML, G Vans W/4L60-E Automatic Transmission

Bulletin No.: Chevrolet 93-36-7A

Date: 10/14/1992

SERVICE INFORMATION

VEHICLE APPLICATIONS: C/K - Trucks Under 8600 GVW S/T - Trucks With 4.3L M/L and G - Vans

TRANSMISSION APPLICATIONS: 1993 HYDRA-MATIC 4L60-E

TRANSMISSION MODELS: All

Some 1993 vehicles equipped with a HYDRA-MATIC 4L60-E transmission may have periodic interruptions in communication between the scan tool (TECH 1, T100) and the controller. These interruptions may cause:

T-100/T-50

• A momentary pause of data on the screen. The T-100/T-50 will attempt to re-establish communications with the controller. If this is successful, then data will continue to be displayed.
• If the attempt to re-establish communication fails, then a LOSS OF COMMUNICATION screen will be displayed.

TECH 1

• The screen to flash
• The screen to display: -"WAITING FOR DATA" -"NO DATA. Reselect or turnoff and check Data Link Connector."
• The control commands not to operate properly.
• The snapshot to trigger during the waiting mode.
• In some cases the transmission device control commands may be disregarded by the controller in the following instances:
• If the brake switch is applied, the controller will ignore the TCC control commands.
• If the "PRNDL SWITCH" indicates: - D4 1st, 2nd, 3rd and 4th gears are allowed - D3 1st, 2nd, and 3rd gears are allowed - D2 1st and 2nd gears are allowed - D1 1st and 2nd gears are allowed
• If current DTC's 24 and 72 are set, only 2nd gear is allowed.
• If current DTC's 81 and 66 are set, only 3rd gear is allowed.

This is due to software constraints within the controller. Replacing the PCM controller will not correct the condition.

Usually, the scan tool resumes communication with the controller within 1-5 seconds. If this does not occur, turn the key off, wait 10 seconds, then turn the key on and reselect the scan tool option.