GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1997 🢒 Venture Ext. 🢒 Engine 🢒 Engine Controls - 3.4L (LA1) 🢒 Data Link Connector Diagnosis

Object Number: 154878 Size: LF
Engine Controls Components
Power, Ground, MIL, DLC
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Class II serial data circuit to the DLC allows bi-directional communication between the PCM and the scan tool.

Diagnostic Aids

Check the following items:

    •  For the PCM to establish communication with the scan tool, system voltage must be between 9.0 and 16.0 volts. If system voltage is not within this range, refer to Charging System Section 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

Number(s) below refer to the step number(s) on the Diagnostic Table:

  1. 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 .

Data Link Connector Diagnosis

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to the Powertrain On Board Diagnostic (OBD) System Check

2
  1. Turn on the ignition switch, engine off.
  2. Connect a test light between the DLC battery feed and ground circuits.

Is the test light on?

--

Go to Step 4

Go to Step 3

3

Probe the DLC battery feed circuit with a J 35616-200 to chassis ground.

Is the test light on?

--

Go to Step 9

Go to Step 10

4
  1. Turn on the ignition switch, engine off.
  2. Probe the Class II serial data circuit at the DLC with a J 39200 digital multimeter (DMM) to ground.

Does the voltage measure the specified value?

0.0V

Go to Step 5

Go to Step 7

5
  1. Turn off the ignition switch, disconnect the PCM.
  2. Turn on the ignition switch, engine off.
  3. Probe the Class 2 serial data circuit at the DLC with a DMM to battery positive voltage.

Does the voltage measure the specified value?

0.0V

Go to Step 6

Go to Step 8

6
  1. Check the Class II serial data circuit for an open between the DLC and the PCM.
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

Go to Step 11

7
  1. Check the Class II serial data circuit for a short to voltage.
  2. If a problem is found, repair as necessary. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

Go to Step 11

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?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

9

Locate and repair open in the DLC ground circuit. Refer to Repair Procedures in Electrical Diagnosis.

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

10

Locate and repair open or short to ground in the DLC battery feed circuit. Refer to Repair Procedures in Electrical Diagnosis.

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

11

Replace the PCM.

Important: :  Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--