GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Was the Data Link Connector System Check performed?

--

Go to Step 2

Go to Data Link Communications System Check .

2

Attempt to establish communication with the same system, same year, on a different vehicle.

Can communication be established?

--

Go to Step 4

Go to Step 3

3

  1. The scan tool may be inoperative.
  2. Verify that the scan tool operates properly.

Does the scan tool operate properly?

--

Go to Step 4

Go to Scan Tool Inoperative .

4

  1. Disconnect the automatic level control sensor connector.
  2. Use the DMM to measure the resistance between terminal B of the automatic level control sensor connector and terminal 8 of the data link connector.

Is the measured resistance within the specified value?

Less than 5 ohms

Go to Step 6

Go to Step 5

5

  1. Locate an open or a high resistance in circuits XM111 and/or XM900.
  2. Repair the open or the high resistance in circuits XM111 and/or XM900.

Is the repair complete?

--

Go to Step 15

--

6

Use the DMM to measure the resistance between terminal 8 of the data link connector and a known good ground.

Is the measured resistance within the specified value?

Less than 5 ohms

Go to Step 7

Go to Step 10

7

  1. Disconnect the cruise control module.
  2. Use the DMM to measure the resistance between terminal 8 of the data link connector and a known good ground.

Is the measured resistance within the specified value?

Less than 5 ohms

Go to Step 9

Go to Step 8

8

  1. There is an internal failure within the cruise control module that is pulling the circuit to ground.
  2. Replace the cruise control module. Refer to Actuator Motor Replacement in Cruise Control.

Is the replacement complete?

--

Go to Step 15

--

9

If all of the modules are disconnected and there is still a short to ground, locate and repair a short to ground in the circuits.

Is the repair complete?

--

Go to Step 15

--

10

Use the DMM to measure the voltage between terminal 8 of the data link connector and a known good ground.

Is the measured voltage within the specified range?

B+

Go to Step 11

Go to Step 14

11

  1. Disconnect the cruise control module.
  2. Use the DMM to measure the voltage between terminal 8 of the data link connector and a known good ground.

Is the measured voltage within the specified value?

B+

Go to Step 13

Go to Step 12

12

  1. There is an internal failure within the cruise control module that is pulling the circuit to B+.
  2. Replace the cruise control module. Refer to Actuator Motor Replacement in Cruise Control.

Is the replacement complete?

--

Go to Step 15

--

13

If all of the modules are disconnected and there is still a short to B+, locate and repair a short to B+ in the circuits.

Is the repair complete?

--

Go to Step 15

--

14

  1. Use the DMM to check for proper voltage and ground circuits to the automatic level control sensor.
  2. If the voltage and ground circuits are OK, replace the automatic level control sensor. Refer to Automatic Level Control Sensor Replacement in Automatic Level Control.

Is the replacement complete?

--

Go to Step 15

--

15

  1. Connect all connectors and components that were disconnected.
  2. Connect the scan tool.
  3. Establish communication with the automatic level control sensor.

Does the scan tool communicate with the automatic level control sensor?

--

System OK

Go to Step 1