Refer to
Power, Ground and MIL
.
Circuit Description
The Class 2 serial data circuit to the DLC allows bi-directional communication between the PCM and the 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
Check the following items:
| • | For the PCM to establish communication with the scan tool, system voltage must be between 9.0 and 18.0 volts. If system voltage is not within this range, refer to Charging System for diagnosis. |
| • | Ensure that the correct application (model year, carline, 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, Vehicle Interface Module, 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, and damaged harness. |
Test Description
Number(s) below refer to the Step number(s) on the Diagnostic Table:
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Does the test lamp illuminate? | -- | ||
3 | Probe both of the DLC ground circuits (cavities 4 and 5) using atest lamp that is connected to B+. Does the test lamp illuminate at both ground circuits? | -- | ||
4 | Probe the Class 2 serial data circuit at the DLC using aJ 39200 Digital Multimeter that is connected to a good ground. Does the voltage measure near the specified value? | 0 V | ||
5 |
Does the test lamp illuminate? | -- | ||
6 | Test the Class 2 serial data circuit for an open. Refer to Wiring Repairs . Did you find and correct the condition? | -- | ||
7 | Test the Class 2 serial data circuit for a short to voltage. Refer to Wiring Repairs . 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 . Did you complete the repair? | -- | -- | |
9 | Locate and repair the open in the affected DLC ground circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |
10 | Locate and repair the open or short to ground in the DLC battery positive voltage circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |
|
Important:: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | -- |
