Refer to Engine Controls Schematics
Cell 21: Power, Ground, MIL, and DLC
.
Circuit Description
The Class 2 serial data circuit to the data link connector DLC allows bi-directional communication between the PCM and the scan tool. If communication between the scan tool and the Powertrain Control Module (PCM) cannot be established, the procedure in the DLC diagnosis table should be used to diagnose the condition.
Diagnostic Aids
Check the following items:
| • | For the PCM to establish communication with the scan tool, system voltage must be between 9.0 and 16.0 volts. If system voltage is not within this range, refer to Diagnostic System Check - Engine Electrical in Engine Electrical. |
| • | Ensure that the correct application (model year, carline, VIN code) has been selected on the scan too. 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 a poor connection, rubbed through wire insulation or a wire broken inside the insulation. |
| • | Check for poor connections or a damaged harness. |
| • | Inspect the PCM harness and connectors for: |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed or damaged terminals |
| • | Poor terminal to wire connection |
| • | Damaged harness |
| • | Use a corresponding mating terminal to test for proper terminal tension. |
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 | Connect a test lamp between the battery feed circuit of the DLC and chassis ground. Does the test lamp illuminate? | -- | ||
4 | Turn ON the ignition, with the engine OFF. Connect a DMM between the Class 2 serial data circuit of the DLC and a good ground. Does the voltage equal the specified value? | 0.0 V | ||
5 |
Does the voltage equal the specified value? | 0.0 V | ||
6 |
Did you find and correct the condition? | -- | ||
7 |
Did you find and correct the condition? | -- | ||
8 | Repair the short to ground in the Class 2 serial data circuit. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | -- | |
9 | Repair the open in the DLC ground circuits. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | -- | |
10 | Repair open or short to ground in the DLC battery feed circuit. Replace the fuse, if necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | -- | |
|
Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the repair? | -- | -- |
