Circuit Description
The provision for communicating with the control module is the Data Link Connector (DLC). It is usually located under the instrument panel. The DLC is used to connect to a scan tool. Some common uses of the scan tool are listed below:
| • | Identifying stored Diagnostic Trouble Codes (DTCs). |
| • | Clearing DTCs. |
| • | Performing output control tests. |
| • | Reading serial data. |
Battery power and ground is supplied for the scan tool through the DLC. The Class 2 serial data circuit to the DLC allows the PCM to communicate with the scan tool. A UART serial data line is used to communicate with other modules such as the Electronic Brake Control Module (EBCM), the Supplemental Inflatable Restraint (SIR) system and the Instrument Panel Cluster (IPC).
Diagnostic Aids
Ensure that the correct application (model year, car line, VIN code) has been selected on the scan tool. If communication still cannot be established, try the scan tool on another vehicle to ensure that the scan tool, or cables are not the cause of the condition.
An intermittent may be caused by the following:
| • | Poor connection |
| • | Rubbed through wire insulation |
| • | Broken wire inside the insulation |
Any circuitry, that is suspected as causing an intermittent complaint, should be thoroughly checked for the following conditions:
| • | Backed out terminals. |
| • | Improper mating of terminals. |
| • | Broken locks. |
| • | Improperly formed or damaged terminals. |
| • | Poor terminals to wiring connection. |
| • | Physical damaged to the wiring harness. |
| • | Corrosion. |
Test Description
The number below refers to the step number on the diagnostic table:
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Does the test lamp illuminate? | -- | ||
3 | Probe both of the DLC ground circuits with a test lamp to B+. Does the test lamp illuminate at both ground circuits? | -- | ||
4 | Probe the Class 2 serial data circuit at the DLC with a DMM connected to ground. Does the voltage approximately equal the specified value? | 0 V | ||
5 |
Does the test lamp illuminate? | -- | ||
6 |
Did you find and correct the condition? | -- | ||
7 |
Did you find and correct the condition? | -- | ||
8 | Locate and repair the short to ground in the Class 2 serial data circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |
9 | Locate and repair the open in the affected DLC ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |
10 | Locate and repair the open or short to ground in the DLC B+ circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |
|
Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the repair? | -- | -- |
