GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1999 🢒 Escalade 🢒 Body and Accessories 🢒 Data Link Communications 🢒 Diagnostic System Check - Data Link Communications

Step

Action

Normal Result(s)

Abnormal Result(s)*

1

With scan tool connected make contact with any of the modules applicable to the vehicle

Scan Tools main menu.
    • Blank Screen
    • No power to the scan tool

Refer to Scan Tool Inoperative

2

Select Diagnostics Circuit Check, Class 2 DTC Check from the scan tools menu. The modules below should be listed:

    • PCM/VCM
    • ABS/TCS
    • VTD/EVO
    • ATCM (Automatic Transfer Case Only)

"No" located in the DTCs present column.

"Yes" located in the DTCs present column.

No Communication with the vehicle, or Diagnostic Link Connector. Refer to Scan Tool Does Not Communicate with Class 2 Data Line

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

No DTCs. Data Only

No communication with the vehicle, or Diagnostic Link Connector. Refer to Scan Tool Does Not Communicate with UART Data Line

4
  1. Select Body Diagnostics from the scan tools menu.
  2. Access E and C Data Line from the scan tools menu.

No DTCs. Data Only

No communication with the vehicle, or Diagnostic Link Connector. Refer to Scan Tool Does Not Communicate with E and C Data Line

5
  1. Establish communication with the Electronic Brake Control Module (EBCM)
  2. Access DTC's using the scan tool. (Vehicles 15,000 GVW and over.)

No DTCs. Data Only

No communication with the vehicle, or Diagnostic Link Connector. Refer to Scan Tool Does Not Communicate with Electronic Brake Control Module

6
  1. Establish communication with the Powertrain Control System(s).
  2. Access DTC's using the scan tool.

No DTCs. Data Only

No communication with the vehicle, or Diagnostic Link Connector. Refer to Scan Tool Does Not Communicate with Vehicle Control Module/Powertrain Control Module .

U1026. Refer to DTC U1026 Loss of ATC Class 2 Communication .

U1041. Refer to DTC U1041 Loss of EBCM Communication .

U1192. Refer to DTC U1192 Loss of VTD Class 2 Serial Data Com .

7
  1. Establish communication with the ATCM.
  2. Access DTC's using the scan tool.

No DTCs. Data Only

U1016. Refer to DTC U1016 Loss of Communications with PCM

U1041. Refer to DTC U1041 Loss of EBCM Communication .

8
  1. Establish communication with the EVO/Passlock Control Module.
  2. Access DTC's using the scan tool.

No DTCs. Data Only

U1016. Refer to DTC U1016 Loss of Communications with PCM

U1255. Refer to DTC U1255 Serial Data Line Malfunction

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