Circuit Description
The Class II 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 16.0V. 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
The number below refers to the step number on the Diagnostic Table:
-
This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On Board Diagnostic (OBD) System Check performed? | -- | ||
2 | Probe both of the DLC ground circuits with a test light to battery positive voltage. Is the test light on at both ground circuits? | -- | ||
3 | Probe the DLC battery feed circuit with a test light to chassis ground. Is the test light on? | -- | ||
4 | Probe the Class II serial data circuit at the DLC with a J 39200 Digital Multimeter (DMM) to ground. Does the voltage measure near the specified value? | 0.0 V | ||
5 |
Is the test light on? | -- | ||
6 |
Was a problem found? | -- | ||
7 |
Was a problem found? | -- | ||
8 | Locate and repair short to ground in the Class II serial data circuit. Refer to Repair Procedures in Electrical Diagnosis. Is the action complete? | -- | -- | |
9 | Locate and repair open in the affected DLC ground circuit(s). Refer to Repair Procedures in Electrical Diagnosis. Is the action complete? | -- | -- | |
10 | Locate and repair open or short to ground in the DLC battery positive voltage circuit. Refer to Repair Procedures in Electrical Diagnosis. Is the action complete? | -- | -- | |
Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- |
