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 serial data circuit to the DLC allows the PCM to communicate with the scan tool. A serial data line is used to communicate with other modules such as the electronic brake control module (EBCM) and the body control module (BCM).
Diagnostic Aids
Ensure that the correct application--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 vehicle to ensure that the scan tool or the 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 of 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 terminal-to-wiring connections |
| • | Physical damage to the wiring harness |
| • | Corrosion |
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
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Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open. | ||||||||||
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check 2.4L or Powertrain On Board Diagnostic (OBD) System Check 3.1L | ||||||
2 |
Is the MIL ON? | -- | Go to Step 3 | Go to Malfunction Indicator Lamp (MIL) Inoperative 2.4L or Malfunction Indicator Lamp (MIL) Inoperative 3.1L | ||||||
3 | Install a scan tool. Does the scan tool power up? | -- | Go to Step 4 | Go to Scan Tool Inoperative | ||||||
4 | Attempt to communicate with the following control modules with the scan tool:
Does the scan tool communicate with the control modules? | -- | Go to Step 7 | Go to Step 5 | ||||||
5 |
Does the scan tool communicate? | -- | Go to Step 10 | Go to Step 6 | ||||||
6 | Test for an open or short to ground in CKT 1807 between the PCM, EBCM and the left IP junction block. Was a condition found and fixed? | Voltage | Go to Step 7 | |||||||
7 |
Was a condition found and fixed? | Voltage | Go to Step 8 | |||||||
8 | Replace the left IP junction block. Is the repair complete? | -- | -- | |||||||
9 | The malfunction may be intermittant. Check the wiring and connectors to the control modules and the DLC. Is the inspection complete? | -- | Go to Diagnostic Aids | -- | ||||||
10 | Test for a short to ground between the BCM and the left IP junction block. Was a condition found and fixed? | -- | Go to Step 11 | |||||||
11 | Replace the BCM. Refer to the following procedures:
Is the repair complete? | -- | -- | |||||||
