GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 Catera 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Scan Tool Does Not Communicate with Automatic Level Control Sensor

Step

Action

Value(s)

Yes

No

1

Was the Data Link Communications System Check performed?

--

Go to Step 2

Go to Data Link Communications System Check

2

Attempt to establish communications with the cruise control module.

Does the scan tool communicate with the cruise control module?

--

Go to Step 3

Go to Step 4

3
  1. Inspect the ALC fuse for an open.
  2. Inspect and test the ALC sensor battery feed circuit at terminal A for proper voltage (11-13 V).
  3. Inspect and test the ground circuit at terminal E.
  4. Inspect the serial data circuit for a poor connection at terminal B. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  5. Make necessary repairs.

Did you find and correct any conditions?

--

Go to Step 5

Go to Step 6

4
  1. Disconnect the cruise control module connector.
  2. Attempt to communicate with the ALC sensor.

Does the scan tool communicate with the ALC sensor?

--

Go to Step 7

Go to Step 8

5

Attempt to establish communications with the ALC sensor.

Does the scan tool communicate with the ALC sensor?

--

System OK

Go to Step 9

6
  1. Disconnect the ALC sensor connector.
  2. Measure the resistance between the connector terminal B and the data link connector (DLC) terminal 8.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 9

Go to Step 10

7

Replace the cruise control module.

Is the replacement complete?

--

Go to Step 5

--

8
  1. Disconnect the connectors from both modules.
  2. Test the serial data circuit, of the DLC, for a short to ground between terminal 8 and each module as follows:
    3. • Cruise Control module connector terminal H
    • ALC sensor connector terminal B

Did you find a short to ground in the serial data circuit?

--

Go to Step 11

Go to Step 12

9

Replace the ALC sensor.

Is the replacement complete?

--

Go to Step 5

--

10

Locate and repair an open in the serial data circuit.

Is the repair complete?

--

Go to Step 5

--

11

Locate and repair the short to ground in the serial data circuit.

Is the repair complete?

--

Go to Step 5

--

12

Test the serial data circuit for a short to voltage.

Did you find a short to voltage in the serial data circuit?

--

Go to Step 13

Go to Step 9

13

Locate and repair the short to voltage in the serial data circuit.

Is the repair complete?

--

Go to Step 5

--