Test Description

1998 Chevrolet Suburban K2500, 7.4 J, Part TimeSECTION Test Description
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  Lack of communication may be due to a malfunction in the GMLAN or the class 2 serial data circuit. The specified procedure will determine the particular condition.
  2. 5:  The presence of DTCs which begin with "U" indicates that some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
Diagnostic System Check - Cruise Control (3.6L)

Step Action Yes No
1 Install a scan tool.
Does the scan tool power up?
Go to Step 2  Go to Scan Tool Does Not Power Up in Data Link Communications
  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the following modules:
    • Engine Control Module (ECM)
    • Electronic Brake Control Module (EBCM)
Does the scan tool communicate with the modules listed above?
Go to Step 3  Go to Data Link References in Data Link Communications
3
IMPORTANT: The engine may start during the following step. Turn the engine OFF as soon as you have observed the Crank power mode.
  1. With a scan tool, access the Class 2 Power Mode in the Diagnostic Circuit Check.
  2. Rotate the ignition switch through all positions while observing the System Power Mode parameter.
Does the System Power Mode parameter reading match the ignition switch position for all switch positions?
Go to Step 4  Go to Power Mode Mismatch in Body Control System
4 Select the DTCs function on the scan tool for the following modules:
  • ECM
  • EBCM

Does the scan tool display any DTCs for the modules listed above?
Go to Step 5  Go to Symptoms - Cruise Control 
Does the scan tool display any DTCs which begin with a "U"? Go to Diagnostic Trouble Code (DTC) List in Data Link Communications Go to Step 6 
6 Does the scan tool display DTC P0562, P0563, P0615, P0616, P0617, P0625, P0626, or P1668? Go to Diagnostic Trouble Code (DTC) List in Engine Electrical Go to Diagnostic Trouble Code (DTC) List 
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.