1

1. Turn the ignition switch to the RUN position.
2. Connect a Scan Tool to the DLC.
3. Attempt to establish communications on CKT 800.

Did the Scan Tool establish communications on CKT 800?

--

Go to Step 2

Go to Scan Tool Does Not Communicate with UART Data Line in Data Link Communications

Attempt to establish communications between the Scan Tool and the HVAC system (Non-E and C).

Did the Scan Tool establish communications with the HVAC system (Non-E and C)?

--

Go to Step 4

Go to Step 3

1. Turn the ignition switch to the OFF position.
2. Disconnect the HVAC programmer connector C2.
3. Turn the ignition switch to the RUN position.
4. Measure the voltage between the following terminals:

4.1.	Terminal cavity C7 of the HVAC programmer connector C2 and terminal 4 of the DLC.

4.2.	Terminal cavity C8 of the HVAC programmer connector C2 and terminal 4 of the DLC

Refer to Measuring Voltage in Wiring Systems.

Does the voltage measure the specified value?

5 V

Go to Step 5

Go to Step 6

Code 1038 can only be viewed as a history code when a serial data line problem is not current.

A current serial data line problem cannot be accessed through the Scan Tool unless the condition occurs in the climate control system.

Is the condition occurring in the climate control system?

--

Go to Step 5

Go to Scan Tool Does Not Communicate with UART Data Line in Data Link Communications

Replace the HVAC programmer. Refer to Programmer Replacement .

Is the repair complete?

--

System OK

--

1. Inspect terminal C7 and terminal C8 of the HVAC programmer harness connector for proper terminal contact.
2. Inspect CKT 800 for opens.
3. Replace the HVAC programmer if all of the terminals and CKT 800 are in proper condition. Refer to Programmer Replacement .

Is the repair complete?

--

System OK

--