UART - Communication Link With Scan Tool Installed

File in Section: 6E - Engine Fuel & Emission

Bulletin No.: 57-65-04

Date: March, 1995

SUBJECT:
UART (Universal Asynchronous Receive and Transmit) Communication Link with Scan Tool Installed

MODELS:
1995 Buick Riviera
1994-95 Oldsmobile Eighty Eight, Ninety Eight
with 3.8L Engine (VINs L, 1 - RPOs L27, L67) and equipped with U2A or UH8 Gauge cluster

The intent of this bulletin is to inform technicians about a normal condition that exists while using a Scan Tool on vehicles equipped as stated above. When the Scan Tool is connected to the vehicle, the UART communication link is disrupted. The disrupted communication link will result in one or more of the following conditions:

VOLT indicator lamp illuminated

HOT indicator lamp illuminated

STOP ENGINE HOT displayed on Oldsmobile with Driver Information Center

BRAKE TO SHIFT lamp illuminated

PRNDL indicator will remain fixed

Use the Scan Tool data to determine actual coolant temperature, battery voltage, or PRNDL position. Output tests of the Instrument Panel indicator lamps using the Scan Tool will not be possible.