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Home >> GMC >> 1998 >> Forward Control 7.4 J >> Repair and Diagnosis >> External Pages >> Different car >> Section 681 (Engine Cooling System) >> Diagnostic Information and Procedures >> Diagnostic System Check - Engine Cooling >> Test Description
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Test Description

WARNING: This page is about a different car, the 2002 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

The number(s) below refer to the step number(s) on the diagnostic table.

  1. 2. Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
  2. 3. Determine if the Instrument Cluster or Powertrain Control Modules have set DTCs which may affect Engine Cooling operation are present.
  3. 4. The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
Fig 1: Diagnostic System Check - Engine Cooling
G01703796Courtesy of GENERAL MOTORS CORP.