GM Service Manual Online
For 1990-2009 cars only

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.

  2. The symptom list in Symptoms will determine the correct diagnostic procedure to use.

  3. The presence of DTCs U1161, U1162, U1163 or U1170 indicate one or more of the door modules is not communicating on the SBI circuits.

  4. The presence of other DTCs which begin with "U" indicate some other system control module is not communicating. The specified procedure will compile all the available information before tests are performed.

Step

Action

Yes

No

1

Install a scan tool.

Does the scan tool power up?

Go to Step 2

Go to Scan Tool Does Not Power Up in Data Link Communications

2

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the following modules:
  3. • The driver door module (DDM)
    • The powertrain control module (PCM)

Does the scan tool communicate with the listed modules?

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

3

Select the Driver Door Module display DTCs function on the scan tool.

Does the scan tool display any DTCs?

Go to Step 4

Go to Symptoms

4

Does the scan tool display DTCs U1161, U1162 or U1170?

Go to DTC U1161 Loss of PDM Serial Data , DTC U1162 Loss of Rear Door Module Serial Data , or DTC U1170 Loss of Driver Door Sw Asm Serial Data

Go to Step 5

5

Does the scan tool display any other DTCs which begin with a U?

Go to Diagnostic Trouble Code (DTC) List in Data Link Communications

Go to Step 6

6

Does the scan tool display DTC B1656?

Go to Diagnostic Trouble Code (DTC) List/Type in Body Control System

Go to Step 7

7

Does the scan tool display DTC B1982 or B1983?

Go to Diagnostic Trouble Code (DTC) List/Type in Engine Electrical

Go to Step 8

8

Does the scan tool display DTC B2240, B2241 or B2242?

Go to Diagnostic Trouble Code (DTC) List/Type in Seats

Go to Step 9

9

Does the scan tool display any DTCs that begin with a P?

Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls - 3.8 L

Go to Diagnostic Trouble Code (DTC) List/Type