Circuit Description
The Data Link Connector check 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 51 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 miss-diagnosis.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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Checking the voltage and ground supply to the scan tool.
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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 in CKT 40. If fuse is OK check for open in CKT 40 or 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 | Was the Powertrain On-Board Diagnostic System Check performed? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | |
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 A Powertrain On Board Diagnostic (OBD) System Check | |
Is the voltage read at both terminals the same or higher than the value shown? | 10.0 Volts | |||
Measure voltage to ground on DLC terminal 16. Is the voltage read the same or higher than the value shown? | 10.0 Volts | |||
5 | Repair the open in the ground circuit that had no or low voltage. Refer to Test Descriptions . Is the repair complete? | -- | -- | |
Is the repair complete? | -- | -- | ||
Turn the ignition ON. Does the scan tool display data? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | ||
Connect the scan tool to another vehicle. Does the scan tool now display data? | -- | |||
9 |
Is the resistance more than the value specified? | 5 ohms | ||
10 |
Is the resistance less than the value specified? | 10K ohms | ||
11 | Repair the open in CKT 1807. Is the repair complete? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | -- |
12 | Repair the short to ground in CKT 1807. Is the repair complete? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | -- |
13 | Replace the defective scan tool. Is the replacement complete? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | -- |
14 | Reconnect the PCM and check for data with the RAC module disconnected. Is data now present? | -- | ||
15 |
Was terminal contact repaired? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | |
16 | Replace the PCM. Refer to PCM Replacement/Programming . Is the replacement complete? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | -- |
17 | Replace the RAC module. Is the replacement complete? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | -- |
