Refer to Engine Control Schematics
Power, Ground, MIL and Data Link
for
a wiring diagram.
Circuit Description
The Class 2 serial data circuit to the DLC allows bi-directional communication between the PCM and a scan tool. If communication between the scan tool and the PCM cannot be established, the procedure in the DLC Diagnosis table should be used to diagnose the condition.
Diagnostic Aids
Inspect the following items:
| • | In order for the PCM to establish communication with the scan tool, the system voltage must be between 9.0 and 16.0 volts. If the system voltage is not within this range, refer to Diagnostic System Check - Engine Electrical for diagnosis. |
| • | Ensure that the correct application, including the model year, the car line, and the VIN code, has been selected on the scan tool. If communication still cannot be established, try the scan tool on another vehiclein order to ensure that the scan tool or the cables are not the cause of the condition. |
| • | An intermittent may be caused by a faulty connection, by rubbed-through wire insulation, or by a broken wire inside the insulation. Inspect the PCM harness and the connectors for the following conditions: |
| - | Broken locks |
| - | Improperly-formed or damaged terminals |
| - | Faulty terminal-to-wire connections |
| - | A damaged harness |
Test Description
The numbers below refer to the step numbers 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 connected 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 measure near 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 the short to ground in the DLC battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming Did you complete the replacement? | -- | -- |
