Cooling Fan Always On 1.8L RPO-LAY
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit/System Description
The fan 1 relay provides power to the fan control module. The fan control module completes the fan motor circuit by providing a path to ground. The module energizes the fan and controls fan speed according to instructions received from the powertrain control module (PCM).
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Verify the HVAC system operates correctly.
- Ignition ON, observe that the fan is not activated.
| ⇒ | If an HVAC system condition is found, repair the HVAC condition first. Refer to Symptoms - HVAC Systems - Manual. |
| ⇒ | If the fan is activated, test the fan control module circuit terminal 2 for an open/high resistance. If the circuit tests normal, replace the PCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for control module replacement, setup, and programming
Cooling Fan Always On 2.4L RPO-LAX
| Table 1: | Cooling Fan 1 Relay |
| Table 2: | Cooling Fan 2 Relay |
| Table 3: | Cooling Fan 3 Relay |
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit/System Description
The powertrain control module (PCM) controls cooling fan operation in either high speed or low speed mode, depending on cooling requirements. To activate a fan, the PCM applies ground to the coil side of the applicable fan relays. This energizes the coil and applies voltage directly to the cooling fan through the switch side of the relay.
Diagnostic Aids
| • | The fan relay electrical contacts may be pitted or sticking. Replace the relay, if tapping gently on the relay, or wiggling the relay causes a change in the relays operation. |
| • | The performance of the cooling relay may be affected by temperature. Check the relay after sitting outside overnight and after running the engine 30 minutes. |
Use the following relay cavity table in order to locate the correct cavities to probe during diagnosis. The table layout corresponds to the cavity layout of the relay block.
Terminal Identification | ||
|---|---|---|
Relay Coil Ignition | Relay Controlled Output | Relay Switch B+ |
Relay Coil Control | ||
Front of Vehicle | ||
Terminal Identification | ||
|---|---|---|
Relay Controlled Input | Ground | Relay Coil Control |
Relay Controlled Output | ||
Relay Coil Ignition | ||
Front of Vehicle | ||
Terminal Identification | ||
|---|---|---|
Relay Controlled Output | Relay Switch B+ | Relay Coil Control |
Relay Coil Ignition | ||
Front of Vehicle | ||
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Verify the HVAC system operates correctly.
- Ignition ON, observe that the fan is not activated.
| ⇒ | If an HVAC system condition is found, repair the HVAC condition first. Refer to Symptoms - HVAC Systems - Manual . |
Circuit/System Testing
- Ignition OFF, disconnect each cooling fan relay one at a time.
- Ignition ON, observe that the cooling fans are not activated.
- If all circuits test normal, test or replace the cooling fan relay.
Important: The following tests must be performed on each cooling fan relay.
| ⇒ | If the fan is activated, test for a short to voltage in the relay controlled output circuit. |
| ⇒ | If the fan is not activated, test for a short to ground in the relay coil control circuits. |
Component Testing
- Ignition OFF, disconnect the relay.
- Test for 85-120 ohms at 20°C (68°F) between terminals 1 and 2.
- Test for infinite resistance between the following terminals:
- Test for less than 2 ohms between terminals 3 and 4.
- Install a 20A fused jumper wire between relay terminal 1 and 12 volts. Install a jumper wire between relay terminal 2 and ground. Test for less than 2 ohms between terminals 3 and 5.
| ⇒ | If the resistance is not within the specified range, replace the relay. |
| • | 5 and 1 |
| • | 5 and 2 |
| • | 5 and 3 |
| • | 1 and 3 |
| • | 2 and 3 |
| ⇒ | If not the specified range, replace the relay. |
| ⇒ | If greater than the specified range, replace the relay. |
| ⇒ | If greater than the specified range, replace the relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
