Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. Connecting a scan tool to the data link connector (DLC) allows communication with the modules for diagnostic purposes.
The engine will not start when there is a total loss of class 2 serial data communication while the ignition is OFF. The following conditions will cause a total loss of class 2 serial data communication:
• | A class 2 serial data circuit shorted to ground |
• | A class 2 serial data circuit shorted to voltage |
• | An internal condition within a module or connector on the class 2 serial data circuit, that causes a short to voltage or ground to the class 2 serial data circuit |
Step | Action | Yes | No | ||||||||
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Schematic Reference: Data Link Connector Schematics Connector End View Reference: Data Link Communications Connector End Views | |||||||||||
1 | Does the scan tool power up? | Go to Step 2 | |||||||||
2 |
Does the scan tool communicate with the PCM on the class 2 serial data circuit? | System OK | Go to Step 3 | ||||||||
3 |
Did you find and correct the condition? | Go to Step 4 | |||||||||
4 | Test the class 2 serial data circuits between the DLC and the PCM and between the PCM and the powertrain interface module (PIM) for the following conditions. Turn ON the ignition when testing for a short to voltage:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 5 | ||||||||
5 | Inspect for poor connections and terminal tension at the harness connector of the suspect module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 6 | ||||||||
6 |
Important: Perform the module programming or setup procedure if required. Replace the suspect module. Did you complete the replacement? | Go to Step 7 | -- | ||||||||
7 |
Important: The scan tool may require a power up reset before communication will occur due to a short on the class 2 serial data circuit. Turn off or disconnect the scan tool before you display DTCs. Did your record any DTCs which begin with a letter U and with a current status? | Go to Step 9 | Go to Step 8 | ||||||||
8 | Did you record any DTCs which do not begin with a letter "U"? | Go to Step 9 | Go to Step 10 | ||||||||
9 | Diagnose the DTCs as directed by the diagnostic procedures for the particular module or concern. Did you complete the action? | Go to Step 10 | -- | ||||||||
10 | Did you diagnose all of the DTCs? | Go to Step 11 | Go to Step 9 | ||||||||
11 | Clear the DTCs using the scan tool. Did you complete the action? | -- |