Was the Data Link Communication Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Data Link Communications

1. Disconnect the automatic level control (ALC) sensor connector.
2. Measure the resistance between the connector terminal B and the data link connector (DLC) terminal 8. Refer to Testing for Continuity in Wiring Systems.

Does the resistance measure less than the specified value?

.5 ohms

Go to Step 3

Go to Step 4

Inspect for poor connections at the ALC sensor connector. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

Did you find and correct a poor connection condition?

--

Go to Step 5

Go to Step 6

Locate and repair an open in the serial data circuit.

Is the repair complete?

--

Go to Step 5

--

Attempt to establish communications with the ALC sensor.

Does the scan tool communicate with the ALC sensor?

--

System OK

--

1. Inspect the ALC fuse for an open.
2. Inspect and test the battery feed circuit at terminal A for proper voltage (11-13 V).
3. Inspect and test the ground circuit at terminal E.
4. Make necessary repairs.

Did you find and correct any conditions?

--

Go to Step 5

Go to Step 7

Test the serial data circuit for a short to ground between DLC terminal 8 and ALC sensor connector terminal B. Refer to Testing for Short to Ground in Wiring Systems.

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

--

Go to Step 8

Go to Step 9

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

Is the repair complete?

--

Go to Step 5

--

Test the serial data circuit for a short to voltage between DLC terminal 8 and ALC sensor connector terminal B. (Turn ON the ignition, leaving the engine OFF, when testing for a short to voltage.)

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

--

Go to Step 10

Go to Step 12

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

Is the repair complete?

--

Go to Step 11

--

Replace the ALC sensor.

Is the replacement complete?

--

Go to Step 5

--

1. Reconnect the ALC sensor.
2. Reconnect any other disconnected connectors.
3. Install the scan tool.
4. Turn ON the ignition, leaving the engine OFF.
5. Attempt to establish communications with the ALC sensor.

Does the scan tool communicate with the ALC sensor?

--

Go to Step 13

Go to Step 11

It is apparent that the module communication condition is intermittent. Refer to the following:

Did you find and correct the condition?

--

Go to Step 5

--