GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1999 🢒 Grand Prix 🢒 Body and Accessories 🢒 Data Link Communications 🢒 Scan Tool Does Not Communicate with E and C Data Line

Step

Action

Value(s)

Yes

No

1

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

Is the voltage within the specified range?

B+ (9-14 V)

Go to Step 2

Go to Step 14

2

Use a 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 15

3

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

Is the voltage within specified range?

B+ (9-14 V)

Go to Step 4

Go to Step 15

4

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 16

5

Attempt to establish communication with the radio on a different vehicle using the scan tool.

Can communication be established with the scan tool?

--

Go to Step 6

Go to Step 17

6
  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 re-attempt to establish communication with the radio.

Can the scan tool communicate with the radio?

--

Go to Step 18

Go to Step 7

7
  1. Turn the ignition switch OFF.
  2. Disconnect the radio connector C 2.
  3. Disconnect the head-up display (HUD) electrical connector (if equipped).
  4. Disconnect the multi-disc CD player electrical connector (if equipped).
  5. Use a DMM in order to measure the resistance between the DLC terminal 5 and terminal 14.

Is the resistance the same as the specified value?

OL (Infinite)

Go to Step 8

Go to Step 19

8
  1. Turn the ignition switch to the RUN position.
  2. Use a DMM in order to measure the voltage between the DLC terminal 5 and terminal 14.

Is the voltage less than the specified value?

1 V

Go to Step 9

Go to Step 20

9
  1. Turn the ignition switch to the OFF position.
  2. Use a DMM in order to measure the resistance between the DLC terminal 14 and the radio harness connector C2 terminal 15.

Is the resistance within the specified value?

0-2 ohms

Go to Step 10

Go to Step 21

10
  1. If the vehicle is not equipped with the multi-disc CD player, go to Step 11 .
  2. Use a DMM in order to measure the resistance between the DLC terminal 14 and the multi-disc CD player harness connector terminal 10.

Is the resistance within the specified value?

0-2 ohms

Go to Step 11

Go to Step 21

11
  1. If the vehicle is not equipped with the head up display, go to Step 12 .
  2. Use a DMM in order to measure the resistance between the DLC terminal 14 and the head up display harness connector terminal A5.

Is the resistance within the specified value?

0-2 ohms

Go to Step 12

Go to Step 21

12
  1. Turn the ignition OFF.
  2. Reconnect the radio only. Leave the other modules disconnected, if equipped.
  3. Turn the ignition switch to the RUN position.
  4. Use a scan tool in order to attempt to establish communication with the radio.

Can the scan tool communicate with the radio?

--

Go to Step 13

Go to Step 22

13
  1. If the vehicle is not equipped with the multi-disc CD player and the head up display, go to Step 18.
  2. Turn the ignition switch OFF.
  3. Reconnect one of the disconnected modules.
  4. Turn the ignition switch to the RUN position.
  5. Use a scan tool in order to attempt to establish communication with the radio.
  6. Repeat Steps 2-5 in this action step until the malfunctioning module is isolated.

Inspect for power, ground and proper connections to the module that is not communicating with the scan tool. Refer to the following sections for service procedures:

    • For the multi-disc CD player, refer to Audio Systems.
    • For the head up display, refer to Head Up Display Schematics.

Is the repair complete?

--

Go to Step 23

--

14

Repair the poor connection or an open in circuit 440.

Is the repair complete?

--

Go to Step 23

--

15

Repair the poor connection or an open in circuit 1550.

Is the repair complete?

--

Go to Step 23

--

16

Repair the poor connection between the DLC terminal 14 and the scan tool.

Is the repair complete?

--

Go to Step 23

--

17

The scan tool may be malfunctioning. Refer to the scan tool instruction manual for additional information.

Is the action complete?

--

Go to Step 23

--

18

The malfunction is intermittent and not present at this time. Inspect the following components for a poor connection or open, a short to B+ or a short to ground in circuit 835:

    • The radio
    • The multi-disc CD player (if equipped)
    • The head up display (if equipped)

Repair as needed.

Is the action complete?

--

Go to Step 23

--

19

Repair the short to ground in circuit 835.

Is the repair complete?

--

Go to Step 23

--

20
  1. Turn the ignition switch OFF.
  2. Repair the short to B+ in circuit 835.

Is the repair complete?

--

Go to Step 23

--

21

Repair the poor connection or an open in circuit 835.

Is the repair complete?

--

Go to Step 23

--

22

Inspect for power, ground and proper connections to the radio. Refer to Audio Systems for additional information.

Is the action complete?

--

Go to Step 23

--

23
  1. Ensure that the ignition switch is OFF.
  2. Reconnect the connectors. Reinstall the components.

Is the action complete?

--

Go to Data Link Communications System Check

--