GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Blazer - 4WD 🢒 Body and Accessories 🢒 Data Link Communications 🢒 Diagnostic System Check - Data Link Communications

Test Description

  1. This step determines if communication is good between the scan tool and the vehicle's components.

    2.

  2. This step inspects the Class 2 communications system connections and any DTCs that may be set.

    3.

  3. This step determines if the scan tool is able to communicate with the UART Data Line.

    4.

  4. This step determines if DTC U1041 is present.

    5.

  5. This step determines if DTC U1016 is present.

Step

Action

Normal Result(s)

Abnormal Result(s)*

1
  1. Turn the ignition switch to the LOCK position.
  2. Connect the scan tool to the data link connector (DLC).
  3. Turn ON the scan tool.

The scan tool turns ON.

Scan Tool Inoperative

2

With scan tool connected, communicate with any of the modules applicable to the vehicle.

The scan tool communicates with all of the components.

3

Select Diagnostics Circuit Check, Class 2 DTC Check from the scan tools menu.

No DTCs are found.

4

  1. Select Body Diagnostics from the scan tools menu.
  2. Select SIR UART Data Line information.
  3. Access the DTCs using the scan tool.

No DTCs are found.

Scan Tool Does Not Communicate with UART Data Line

5

  1. Establish communication with the electronic brake control module (EBCM).
  2. Using the scan tool, access the DTCs.

The scan tool communicates with the EBCM. No DTCs are found.

DTC U1041 Loss of EBCM Communication

6

  1. Establish communication with the powertrain control module (PCM).
  2. Using the scan tool, access the DTCs.

The scan tool communicates with the PCM. No DTCs are found.

DTC U1016 Loss of Communications with PCM

* Refer to the appropriate symptom diagnostic table for the applicable abnormal result.