The numbers below refer to the step number(s) on the diagnostic table.
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.
The symptoms list in Symptoms will determine the correct diagnostic procedure to use.
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.
The presence of DTC P0601, P0602, P0603, P0604, P0606 or P1621 indicates an internal fault in the PCM.
The presence of DTC B1000, B1004, B1007 or B1009 indicates an internal module fault.
Step | Action | Yes | No | ||||||||||||||
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Schematic Reference: Theft Deterrent System Schematics | |||||||||||||||||
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 | ||||||||||||||
Does the scan tool communicate with all of the listed control modules? | Go to Step 3 | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications | |||||||||||||||
3 |
Important: Important: The engine may start during the following step. Turn OFF the engine as soon as you have observed the Crank power mode.
Important: Insure that all ignition switch positions are observed including the OFF position. Does the Class 2 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 | ||||||||||||||
Select the display DTC function on the scan tool for the following modules:
Does the scan tool display any DTCs? | Go to Step 5 | ||||||||||||||||
Does the scan tool display any DTCs which begin with a "U"? | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications | Go to Step 6 | |||||||||||||||
Does the scan tool display DTC P0601, P0602, P0603, P0604, P0606 or P1621? | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.5 L or Diagnostic Trouble Code (DTC) List in Engine Controls - 4.0 L | Go to Step 7 | |||||||||||||||
Does the scan tool display DTC B1000, B1004, B1007, or B1009? | Go to Diagnostic Trouble Code (DTC) List in Body Control System | Go to Step 8 | |||||||||||||||
8 | Does the scan tool display DTC B1327 Battery/Source volts low? | Go to Diagnostic Trouble Code (DTC) List in Engine Electrical |