Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: Lack of communication may be due to a malfunction of the class 2. The specified procedure will determine the particular condition.
- 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 engine control module (ECM) or powertrain control module (PCM). Does the scan tool communicate with the ECM/PCM? | Go to Step 3 | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications |
| 3 | Select the ECM/PCM. 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 Diagnostic Trouble Code (DTC) List |
Diagnostic System Check - Engine Cooling
The numbers below refer to the step numbers on the diagnostic table.
- 2: Verifies the normal status of the signal circuit to the body control module.
- 3: Tests for voltage at the coolant level switch. The BACKUP fuse supplies power to the voltage side of the coolant level switch.
- 4: Verifies that the body control module is providing ground to the coolant.
| Step | Action | Yes | No |
|---|---|---|---|
| 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 | Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, observe the low coolant level switch input in the body control module (BCM), switch inputs data list. Does the scan tool display normal state? | Go to Diagnostic Aids | Go to Step 3 |
| 3 | Turn OFF the ignition. Disconnect the coolant level switch. Turn ON the ignition, with the engine OFF. Probe the ignition 1 voltage circuit of the coolant level switch with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 4 | Go to Step 9 |
| 4 | Connect a test lamp between the coolant level switch signal of the coolant level switch and the ignition 1 voltage circuit of the coolant level switch. With a scan tool, observe the low coolant switch input status. Does the scan tool display normal state? | Go to Step 7 | Go to Step 5 |
| 5 | Test the switch signal of the coolant level switch for a short to voltage or an open. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 8 |
| 6 | Test the switch signal of the coolant level switch for a short to ground. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 8 |
| 7 | Inspect for poor connections at the coolant level switch. 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 12 | Go to Step 10 |
| 8 | Inspect for poor connections at the harness connector of the body control module. 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 12 | Go to Step 11 |
| 9 | Repair the ignition 1 voltage circuit of the coolant level switch. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 12 | |
| 10 | Replace the coolant level switch. Refer to Surge Tank Replacement . Did you complete the replacement? | Go to Step 12 | |
| 11 | IMPORTANT: Perform the setup procedure for the body control module. Replace the body control module. Refer to Body Control Module Replacement in Body Control System.Did you complete the replacement? | Go to Step 12 | |
| 12 | 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 setup procedure for the body control module. |
DTC B0936 Circuit
The numbers below refer to the step numbers on the diagnostic table.
- 2: Listen for an audible click when the low speed fan relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
- 3: Listen for an audible click when the low and high speed fan relays operate. Command both the ON and OFF states. Repeat the commands as necessary.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Engine Cooling Schematics (L61) Engine Cooling Schematics (L66) 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 | Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, command the Fan Control 1 ON and OFF. Does the low speed fan relay turn ON and OFF with each command? | Go to Step 3 | Go to Step 4 |
| 3 | With a scan tool, command the Fan Control 2 ON and OFF. Do the low and the high speed fan relays turn ON and OFF with each command? | Go to Diagnostic Aids | Go to Step 6 |
| 4 | Turn OFF the ignition. Disconnect the low speed fan relay. Turn ON the ignition, with the engine OFF. Probe the battery positive circuit of the low speed fan relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 5 | Go to Step 14 |
| 5 | Connect a test lamp between the control circuit of the low speed fan relay and the battery positive voltage circuit of the low speed fan relay. With a scan tool, command the Fan Control 1 ON and OFF. Does the test lamp turn ON and OFF with each command? | Go to Step 11 | Go to Step 8 |
| 6 | Turn OFF the ignition. Disconnect the high speed fan relay. Turn ON the ignition, with the engine OFF. Probe the battery positive voltage circuit of the high speed fan relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 7 | Go to Step 14 |
| 7 | Connect a test lamp between the control circuit of the high speed fan relay and the battery positive voltage circuit of the high speed fan relay. With a scan tool, command the Fan Control 2 ON and OFF. Does the test lamp turn ON and OFF with each command? | Go to Step 12 | Go to Step 8 |
| 8 | Does the test lamp remain illuminated with each command? | Go to Step 10 | Go to Step 9 |
| 9 | Test the control circuit of the appropriate relay for a short to voltage or an open. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 18 | Go to Step 15 |
| 10 | Test the control circuit of the appropriate relay for a short to ground. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 18 | Go to Step 13 |
| 11 | Inspect for poor connections at the low speed 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 18 | Go to Step 15 |
| 12 | Inspect for poor connections at the high speed 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 18 | Go to Step 16 |
| 13 | Inspect for poor connections at the harness connector of the ECM. 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 18 | Go to Step 17 |
| 14 | Repair the battery positive voltage circuit for an open or high resistance. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 18 | |
| 15 | Replace the low speed fan relay. Did you complete the repair? | Go to Step 18 | |
| 16 | Replace the high speed fan relay. Did you complete the repair? | Go to Step 18 | |
| 17 | IMPORTANT: Perform the programming procedure for the ECM. Replace the ECM. Refer to Engine Control Module (ECM) Replacement in Engine Controls - 2.2LDid you complete the replacement? | Go to Step 18 | |
| 18 | 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 ECM. |
DTC P0480, P0481, P0691, P0692, P0693, P0694, or P1650 (L61) Circuits
The numbers below refer to the step numbers on the diagnostic table.
- 2: Listen for an audible click when the cooling fan 1 relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
- 3: Listen for an audible click when the cooling fan 2 and cooling fan 3 relays operate. Command both the ON and OFF states. Repeat the commands as necessary.
- 4: Tests for voltage at the coil side of the cooling fan 1 relay. The COOL FAN #1 fuse supplies battery positive voltage to the coil side of the cooling fan 1 relay.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Engine Cooling Schematics (L61) Engine Cooling Schematics (L66) 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 | Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, command the Fan Control 1 ON and OFF. Does the cooling fan 1 relay turn ON and OFF with each command? | Go to Step 3 | Go to Step 4 |
| 3 | Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, command the Fan Control 2 ON and OFF. Do the cooling fan 2 and the cooling fan 3 relays turn ON and OFF with each command? | Go to Diagnostic Aids | Go to Step 6 |
| 4 | Turn OFF the ignition. Disconnect the cooling fan 1 relay. Turn ON the ignition, with the engine OFF. Probe the battery positive voltage circuit of the cooling fan 1 relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 5 | Go to Step 16 |
| 5 | Connect a test lamp between the control circuit of the cooling fan 1 relay and the battery positive voltage circuit of the cooling fan 1 relay. With a scan tool, command the Fan Control 1 ON and OFF. Does the test lamp turn ON and OFF with each command? | Go to Step 12 | Go to Step 9 |
| 6 | Turn OFF the ignition. Disconnect the cooling fan 3 relay. Turn ON the ignition, with the engine OFF. Probe the battery positive voltage circuit of the cooling fan 3 relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 7 | Go to Step 16 |
| 7 | Connect a test lamp between the control circuit of the cooling fan 3 relay and the battery positive voltage circuit of the cooling fan 3 relay. With a scan tool, command the Fan Control 2 and 3 ON and OFF. Does the test lamp turn ON and OFF with each command? | Go to Step 14 | Go to Step 8 |
| 8 | Turn Off the ignition. Disconnect the cooling fan 2 relay. Turn ON the ignition with the engine OFF. Connect a test lamp between the control circuit of the cooling fan 2 relay and the battery positive voltage circuit of the cooling fan 2 relay. With a scan tool, command the Fans Control 2 and 3 ON and OFF. Does the test lamp turn ON and OFF with each command? | Go to Step 13 | Go to Step 9 |
| 9 | Does the test lamp remain illuminated with each command? | Go to Step 11 | Go to Step 10 |
| 10 | Test the control circuit of the appropriate 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 21 | Go to Step 15 |
| 11 | Test the control circuit of the appropriate 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 21 | Go to Step 15 |
| 12 | Inspect for poor connections at the cooling fan 1 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 21 | Go to Step 17 |
| 13 | Inspect for poor connections at the cooling fan 2 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 21 | Go to Step 18 |
| 14 | Inspect for poor connections at the cooling fan 3 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 21 | Go to Step 19 |
| 15 | Inspect for poor connections at the harness connector of the 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 21 | Go to Step 20 |
| 16 | Repair the battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 21 | |
| 17 | Replace the cooling fan 1 relay. Did you complete the replacement? | Go to Step 21 | |
| 18 | Replace the cooling fan 2 relay. Did you complete the replacement? | Go to Step 21 | |
| 19 | Replace the cooling fan 3 relay. Did you complete the replacement? | Go to Step 21 | |
| 20 | IMPORTANT: Perform the programming procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 3.5L.Did you complete the replacement? | Go to Step 21 | |
| 21 | 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, P0481, P0691, P0692, P0693, P0694, or P1650 (L66) Circuits
Symptoms - Engine Cooling
| IMPORTANT | Review the system operation in order to familiarize yourself with the system functions. Refer to Cooling System Description and Operation . |