Circuit Description
The Data Link Connector Diagnosis is used to identify the cause of an inoperative scan tool. Possible faults include scan tool non-power up and lack of communication between the scan tool and the PCM. The DLC supplies power to the scan tool through CKT 40 to terminal 16. The ground to the scan tool is supplied through CKT 451 to terminal 5. The serial data (communication) is supplied to the scan tool through CKT 1807 to terminal 2.
Diagnostic Aids
Perform the Powertrain On Board Diagnostic System Check before performing this chart to help prevent mis-diagnosis.
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
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Checking the voltage and ground supply to the scan tool. If proper voltage is present retest circuits with a test lamp to verify current flow is adequate.
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Checking if the fault is power or ground circuit related.
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Terminal 4 of the DLC connector is the ground circuit for scan tool data communications and terminal 5 is the power ground circuit for the scan tool.
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If the fuse is blown check for a short to ground. If fuse is OK check for open circuit or a lack of voltage to the fuse.
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If communication is present between the scan tool and PCM then the fault is not present or was poor terminal contact at the DLC connector.
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Checking if the fault is vehicle or scan tool related.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you performed the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |
2 | Perform the PCM Power and Ground Check table and the Powertrain Ground Check table and return to this step. Was a repair made in either table? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | Go to Step 3 |
Is the voltage read at both terminals the same or higher than the value shown? | 10.0 Volts | Go to Step 7 | Go to Step 4 | |
Measure voltage to ground on DLC terminal 16. Is the voltage read the same or higher than the value shown? | 10.0 Volts | Go to Step 5 | Go to Step 6 | |
5 | Repair the open in the ground circuit that had no or low voltage. Refer to Test Descriptions . Is the repair complete? | -- | Go to Step 7 | -- |
Is the repair complete? | -- | Go to Step 7 | -- | |
Turn the ignition ON. Does the scan tool display data? | -- | Go to Step 8 | ||
Connect the scan tool to another vehicle. Does the scan tool now display data? | -- | Go to Step 9 | Go to Step 13 | |
9 |
Is the resistance more than the value specified? | 5 ohms | Go to Step 11 | Go to Step 10 |
10 |
Is the resistance less than the value specified? | 10K ohms | Go to Step 12 | Go to Step 14 |
11 | Repair the open in the Class 2 circuit. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
12 | Repair the short to ground in the Class 2 circuit. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
13 | Replace the defective scan tool. Is the replacement complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
14 | Reconnect the PCM and check for data with the RAC module disconnected. Is data now present? | -- | Go to Step 17 | Go to Step 15 |
15 |
Was terminal contact repaired? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | Go to Step 16 |
16 | Replace the PCM. Is the replacement complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
17 | Replace the RAC module. Is the replacement complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
