GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Data Link Communications System Check?

--

Go to Step 2

Go to Data Link Communications System Check

2

Use a J 39200 Digital Multimeter (DMM) in order to measure the voltage between the Data Link Connector DLC terminal 16 and the ground.

Is the voltage within the specified range?

B+

Go to Step 3

Go to Step 11

3

Use a J 39200 DMM in order to measure the voltage between B+ and DLC terminal 5.

Is the voltage within the specified range?

B+

Go to Step 4

Go to Step 12

4

Use a J 39200 DMM in order to measure the voltage between B+ and DLC terminal 4.

Is the voltage within the specified range?

B+

Go to Step 5

Go to Step 23

5

Inspect for a proper connection of the Scan Tool to the DLC.

Is the connection OK between the Scan Tool and the DLC?

--

Go to Step 6

Go to Step 13

6

Use the Scan Tool in order to establish communication with the PCM on a different vehicle.

Can communication be established with the Scan Tool ?

--

Go to Step 7

Go to Step 14

7

  1. Reconnect the Scan Tool to the DLC.
  2. Turn the ignition switch to RUN.
  3. Use a Scan Tool in order to establish communication with the theft deterrent module.

Can the Scan Tool communicate with the theft deterrent module?

--

Go to Step 15

Go to Step 8

8

  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the PCM connector C1.
  3. Disconnect the theft deterrent module electrical connector.
  4. Use a J 39200 DMM in order to measure the resistance between the DLC terminal 8 and the DLC terminal 5.

Is the resistance less than the specified value?

1 V

Go to Step 9

Go to Step 16

9

  1. Turn the ignition switch RUN.
  2. Use a J 39200 DMM in order to measure the voltage between the DLC terminal 8 and the DLC connector terminal 5.

Is the voltage less than the specified value?

1 V

Go to Step 10

Go to Step 17

10

Check continuity in CKT 728 between the DLC terminal 8 and the theft deterrent module terminal A5.

Is there continuity?

--

Go to Step 25

Go to Step 26

11

Does the radio work?

--

Go to Step 19

Go to Step 20

12

Does the instrument cluster display work?

--

Go to Step 23

Go to Step 24

13

Repair the poor connection between the DLC and the Scan Tool .

Is the repair complete?

--

Go to Step 18

--

14

Determine if the Scan Tool is malfunctioning.

Refer to the scan tool instruction manual for additional information.

Is the repair complete?

--

Go to Step 18

--

15

  1. If malfunction is not present or intermittent, inspect the theft deterrent module for a poor connection, short to B+, or short to ground in CKT 728.
  2. Repair as needed.

Is the action complete?

--

Go to Step 18

--

16

Repair the short to ground in CKT 728.

Is the repair complete?

--

Go to Step 18

--

17

  1. Turn the ignition switch to the LOCK position.
  2. Repair the short to voltage in CKT 728.

Is the repair complete?

--

Go to Step 18

--

18

  1. Ensure that the ignition switch is in the LOCK position.
  2. Reinstall the connectors/components removed.

Is the action complete?

--

Go to Data Link Communications System Check

--

19

Repair the poor connection or open in CKT 640 between the DLC terminal 16 and S202.

Has the repair been made?

--

Go to Step 18

--

20

Check fuse 10 for an open.

Is fuse 10 OK?

--

Go to Step 21

Go to Step 22

21

Repair a poor connection or open in CKT 640 between the fuse block and S202.

Has the repair been made?

--

Go to Step 18

--

22

Replace fuse 10.

Has the repair been made?

--

Go to Step 18

--

23

Repair a poor connection or an open in CKT 1550 between the DLC and S211.

Has the repair been made?

--

Go to Step 18

--

24

Repair a poor connection or an open in CKT 1550 between S211 and G201.

Has the repair been made?

--

Go to Step 18

--

25

Replace the theft deterrent module.

Has the repair been made?

--

Go to Step 18

--

26

Repair the poor connection or open in CKT 728.

Is the repair complete?

--

Go to Step 18

--