Diagnostic Starting Point - Engine Cooling
Begin the system diagnosis by reviewing the Cooling System Description and Operation . Reviewing the Description and Operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the Description and Operation information will also help you determine if the condition described by the customer is normal operation. Refer to Symptoms - Engine Cooling in order to identify the correct procedure for diagnosing the system and where the procedure is located.
Scan Tool Output Controls
| Scan Tool Output Control | Additional Menu Selection(s) | Description |
|---|---|---|
| A/C Compressor | Engine Output Controls | Activates the A/C compressor relay. The normal commanded state of the A/C relay is NONE. The relay status can also be monitored on the scan tool data parameter A/C Relay Command. The powertrain control module (PCM) will inhibit the operation of the A/C relay when the ambient air temperature is low enough to cause icing of the evaporator core. Engaging the A/C relay will also engage the cooling fan at low speed. |
Scan Tool Output Controls
Scan Tool Data List
| Scan Tool Parameter | Data List | Units Displayed | Typical Data Value |
|---|---|---|---|
| A/C Clutch | Engine Data | On/Off | Off |
| A/C Request Signal | Engine Data | Yes/No | No |
| ECT Sensor | Engine Data | C°/F° | 80-90°C /176-194°F |
Scan Tool Data List
Symptoms - Engine Cooling
| IMPORTANT | Review the Cooling System Description and Operation in order to familiarize yourself with the system functions. |
Visual/Physical Inspection
- Inspect for aftermarket devices which could affect the operation of the system. Refer to «Checking Aftermarket Accessories»(ref-200048-S26121749732005102000000) in Wiring Systems.
- Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
- Inspect all related ground points for being clean and tight.
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom
- «Cooling Fan Always On (Always On in Low Speed)»(ref-200120-S29416982782005102000000) or «Cooling Fan Always On (Always On in High Speed)»(ref-200120-S14431748762005102000000)
- «Cooling Fan Inoperative (Inoperative in Low Speed)»(ref-200120-S11677674062005102000000) or «Cooling Fan Inoperative (Inoperative in High and Low Speeds)»(ref-200120-S32146376642005102000000) or «Cooling Fan Inoperative (Inoperative in High Speed)»(ref-200120-S34162269242005102000000) or «Cooling Fan Inoperative (Low Speed Operates in High Speed)»(ref-200120-S01605007012005102000000)
- «Engine Overheating»(ref-200120-S05258343522005102000000)
- «Loss of Coolant»(ref-200120-S32312501632005102000000)
- «Thermostat Diagnosis»(ref-200120-S26498187752005102000000)
- «Engine Fails To Reach Normal Operating Temperature»(ref-200120-S36160931522005102000000)
Thermostat Diagnosis
- Remove the thermostat from the vehicle in order to perform the thermostat test. Refer to «Thermostat Replacement»(ref-200120-S20707090252005102000000) .
- Fill a pan with a 50/50 mixture of ethylene glycol and water. Suspend the thermostat (1) and a thermometer (3) in the pan. Do not place the thermostat (or thermometer) on the bottom of the pan. The concentration of heat is uneven at the bottom of the pan. This condition may cause inaccurate temperature measurements.
- Place the pan on a burner (2).
- Heat the solution.
- Use a thermometer (3) in order to measure the temperature of the solution.
- Ensure that the following specifications exist: The thermostat valve opening temperature is within 80°C to 84°C (176°F to 183°F). The valve lift is 8 mm (0.31 in) or more at 95°C (203°F). If the above specifications are not met, replace the thermostat (1).
- Verify that the valve spring is tight when the thermostat is fully closed. Replace the thermostat if the spring is not tight.
Cooling System Leak Testing
Tools Required
- J 24460-01 Cooling System Tester
- J 41336-2 Radiator Test Adapter
- J 41336-1 Radiator Cap Test Adapter
Leak Testing Procedure (On Vehicle)
- After the system has cooled, remove the radiator pressure cap.
- Connect the cooling system tester, J 24460-01, and the adapter, J 41336-2, to the radiator neck.
- Apply normal system operating pressure. Do not exceed 138 kPa (20 psi).
- The system should hold pressure for about two minutes. Watch the gauge needle for an indication of a leak. Examine all cooling system connections and components, including the radiator and the heater core, for leaking coolant.
- Tighten the hose connections and/or repair as required.
- Test the radiator cap with J 24460-01 and J 41336-1 in order to ensure that the cap maintains the correct pressure.
- Slowly apply pressure. If the cap fails to hold 103 kPa (15 psi), replace the cap.