The numbers below refer to the step numbers 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.
Tests for an open in the Passlockā¢ sensor signal circuit which may not set a DTC B2958 under certain conditions.
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, P0604, or P0606 indicates an internal fault in the powertrain control module (PCM).
The presence of DTC B1000 indicates an internal module fault.
The presence of DTC P1637, P1638, P0562 or P0563 indicates a low or high voltage condition.
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 | ||||||
Does the scan tool communicate with all 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: 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 | ||||||
4 | Select the display DTCs function on the scan tool for the following control modules:
Does the scan tool display any DTCs? | Go to Step 6 | Go to Step 5 | ||||||
Dose the scan tool display OPEN? | Go to DTC B2957 | ||||||||
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 7 | |||||||
Does the scan tool display DTC P0601, P0602, P0604, or P0606? | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 4.8L, 5.3L, and 6.0L | Go to Step 8 | |||||||
Does the scan tool display DTC B1000? | Go to DTC B1000 in Body Control System | Go to Step 9 | |||||||
Does the scan tool display DTC P1637, P1638, P0562 or P0563? | Go to Diagnostic Trouble Code (DTC) List in Engine Electrical |