For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Battery Positive Voltage (DLC) | 1 | 1 | -- | --
Ground (DLC) | -- | 1 | -- | --
1. Scan Tool Does Not Power Up

### Circuit/System Description

The data link connector (DLC) is a standardized 16 cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following:

• | Scan tool power battery positive voltage at terminal 16

• | Scan tool power ground at terminal 4

• | Common signal ground at terminal 5

### Diagnostic Aids

• | The scan tool will power up with the ignition OFF. Some modules however, will not communicate unless the ignition is ON and the power mode master (PMM) module sends the appropriate power mode message.

• | If the battery positive voltage, ground circuits and connections of the DLC are functioning properly, the malfunction must be due to the scan tool/CANdi module.

### Reference Information

#### Schematic Reference

Data Communication Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Data Link Communications Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

1. Ignition ON, test for battery voltage between the battery positive voltage circuit of the DLC and ground.

⇒ | If less than battery voltage, test the voltage supply circuit for a short to ground or an open/high resistance.

2. Test for less than 1.0 ohm between the ground circuit of the DLC and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. If all tests normal, refer to the scan tool/CANdi module user guide.