Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Inspect for a loss of coolant. Refer to Loss of Coolant . Is there a loss of coolant? | -- | Go to Step 2 | Go to Step 3 |
2 | Fill the system to the specified level, then retest. Does the engine overheat? | -- | Go to Step 3 | System OK |
3 | Inspect for a faulty engine coolant temperature (ECT) sensor. Is the sensor operating properly? | -- | Go to Step 4 | Go to Step 6 |
4 | Inspect for a loss of system pressure. Is there a loss of system pressure? | -- | Go to Step 6 | Go to Step 5 |
5 | Inspect for a low coolant concentration level. Is the coolant concentration low? | -- | Go to Step 6 | Go to Step 7 |
6 | Repair or install new parts as necessary, then retest. Does the engine overheat? | -- | Go to Step 7 | System OK |
7 | Inspect for incorrect drive belt tension. Refer to Drive Belt Tensioner Diagnosis in Engine Mechanical - 4.3L. Is the belt tension correct? | -- | Go to Step 8 | Go to Step 6 |
8 | Inspect for retarded ignition timing. Is the timing retarded? | -- | Go to Step 6 | Go to Step 9 |
9 | Inspect for an obstructed radiator air flow or bent fins. Is the radiator air flow obstructed? | -- | Go to Step 6 | Go to Step 10 |
10 | Inspect for a pinched or leaking coolant recovery reservoir hose. Is the reservoir hose OK? | -- | Go to Step 11 | Go to Step 6 |
11 | Inspect for an inoperative cooling fan. Refer to Fan Clutch Diagnosis . Is the fan operating properly? | -- | Go to Step 12 | Go to Step 6 |
12 | Inspect the coolant thermostat. Refer to Thermostat Diagnosis . Does the thermostat fail to open or open too late? | -- | Go to Step 6 | Go to Step 13 |
13 | Inspect for a faulty water pump. Is the water pump operating properly? | -- | Go to Step 14 | Go to Step 6 |
14 | Inspect for a loose, damaged or missing air deflector. Is this system OK? | -- | Go to Step 15 | Go to Step 6 |
15 | Inspect the radiator cooling capacity. Is the radiator the specified one for the vehicle accessory package (including aftermarket items)? | -- | Go to Step 16 | Go to Step 6 |
16 | Does the overheating occur only when pulling a trailer? Is the trailer weight, plus the vehicle weight less than the GCWR for the vehicle? | -- | Go to Step 17 | Go to Step 15 |
17 | Does the overheating occur with prolonged idling (especially with the AC ON)? | -- | -- | Go to Step 1 |
