Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
- 3: Determine if the powertrain control module (PCM) has set DTCs which may affect engine cooling operation are present.
- 4: The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Install a scan tool. Does the scan tool power up? | Go to Step 2 | Go to Scan Tool Does Not Power Up in Data Link Communications |
| 2 | Turn ON the ignition, with the engine OFF. Attempt to establish communication with the powertrain control module (PCM). Does the scan tool communicate with the PCM? | Go to Step 3 | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications |
| 3 | Select the powertrain control module display DTCs function on the scan tool. Does the scan tool display any DTCs? | Go to Step 4 | Go to Symptoms - Engine Cooling |
| 4 | Does the scan tool display any DTCs which begin with a "U"? | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications | Go to Symptoms - Engine Cooling |
Diagnostic System Check - Engine Cooling
The numbers below refer to the step numbers on the diagnostic table.
- 2: Listen for an audible click when the cooling fan relay operates. Command both the ON and OFF states. Repeat the commands as necessary. The appropriate cooling fan relay is the cooling fan relay that set the DTC.
- 3: Listen for an audible click when the cooling fan relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Engine Cooling Schematics Connector End View Reference: Cooling System Connector End Views | |||
| 1 | Did you perform the Engine Cooling Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Engine Cooling |
| 2 | Turn OFF the A/C. Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, command the appropriate Fan Relay ON and OFF. Does the appropriate cooling fan relay turn ON and OFF with each command? | Go to Diagnostics Aids | Go to Step 3 |
| 3 | Turn OFF the ignition. Disconnect the appropriate cooling fan relay. Turn ON the ignition, with the engine OFF. Probe the ignition 1 voltage circuit of the appropriate cooling fan relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 4 | Go to Step 8 |
| 4 | Connect a test lamp between the appropriate cooling fan relay control circuit and the ignition 1 voltage circuit of the appropriate cooling fan relay. With a scan tool, command the appropriate Fan Relay ON and OFF. Does the test lamp turn ON and OFF with each command? | Go to Step 9 | Go to Step 5 |
| 5 | Does the test lamp remain illuminated with each command? | Go to Step 7 | Go to Step 6 |
| 6 | Test the control circuit of the appropriate cooling fan relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 10 |
| 7 | Test the control circuit of the appropriate cooling fan relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 10 |
| 8 | Repair the ignition 1 voltage circuit of the appropriate cooling fan relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 13 | |
| 9 | Inspect for poor connections at the appropriate cooling fan relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 11 |
| 10 | Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
| 11 | Replace the appropriate cooling fan relay. Refer to Cooling Fan Relay Replacement (Low Speed) or Cooling Fan Relay Replacement (High Speed) . Did you complete the replacement? | Go to Step 13 | |
| 12 | IMPORTANT: Perform the programming procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L.Did you complete the replacement? | Go to Step 13 | |
| 13 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? | Go to Step 2 | System OK |
| IMPORTANT |
|---|
| Perform the programming procedure for the PCM. |
DTC P0480 or P0481