GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Was the entire Data Link Connector (DLC) system check performed?

--

Go to Step 2

Go to Data Link Communications System Check

2

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+ (9-14 V)

Go to Step 3

Go to Step 4

3

Inspect for proper connection of the scan tool to the DLC.

Is the connection OK between the scan tool and the DLC?

--

Go to Step 5

Go to Step 6

4

Repair a poor connection or open in circuit 1550 between the DLC and ground.

Is the repair complete?

--

Go to Step 18

--

5

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 8

6

Repair the poor connection between the DLC and the scan tool.

Is the repair complete?

--

Go to Step 18

--

7

  1. Reconnect the scan tool to the DLC.
  2. Turn the ignition switch to the RUN position.
  3. Use a scan tool in order to establish communication with the Powertrain Control Module (PCM).

Can the scan tool communicate with the PCM?

--

Go to Step 9

Go to Step 10

8

Determine if the scan tool is malfunctioning.

Refer to the scan tool instruction manual for additional information.

Is the action complete?

--

Go to Step 18

--

9

  1. Malfunction is not present or intermittent.
  2. Inspect the PCM, SDM, DID, and EBCM connectors for a poor connection, short to B+, or short to ground in CKT 800. Repair as necessary.

Is the action complete?

--

Go to Step 18

--

10

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the PCM connector C1.
  3. Disconnect the SDM connector.
  4. Disconnect the EBCM connector C1.
  5. Disconnect the DID connector.
  6. Use a J 39200 , DMM in order to measure the resistance between the DLC terminal 9 and the DLC terminal 5.

Is the resistance the same as the specified value?

Infinite

Go to Step 11

Go to Step 12

11

  1. Turn the ignition switch to the RUN position.
  2. Use a J 39200 , DMM in order to measure the voltage between the DLC terminal 9 and the DLC terminal 5.

Is the voltage within the specified value?

Less than 1 V

Go to Step 13

Go to Step 14

12

Repair the short to ground in CKT 800.

Is the repair complete?

--

Go to Step 18

--

13

Check continuity between DLC terminal 9 and the PCM connector C1 terminal 15.

Is there continuity?

--

Go to Step 15

Go to Step 16

14

  1. Turn the ignition switch to the OFF position.
  2. Repair the short to voltage in CKT 800.

Is the repair complete?

--

Go to Step 18

--

15

  1. Reconnect the PCM connector C1.
  2. Check for a short to ground in circuit 800.

Is a short to ground present?

--

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

Go to Step 17

16

Repair the poor connection or an open in CKT 800.

Is the repair complete?

--

Go to Step 18

--

17

  1. Reconnect the EBCM connector C1.
  2. Check for a short to ground in circuit 800.

Is a short to ground present?

--

Go to Diagnostic System Check - ABS in Antilock Brake System

Go to SIR Diagnostic System Check in SIR

18

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

Is the action complete?

--

Go to Data Link Communications System Check

--