Cooling Fan Diagnosis
- Install scan tool. Turn ignition on, engine off. If DTCs P0480 or P0481 are present, repair DTCs first. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If DTCs are not present, using scan tool, perform 3 SPEED FAN test while monitoring each fan speed. If both fans work correctly at all 3 speeds, problem is intermittent. If both fans do not work correctly at all 3 speeds, go to next step.
- Using scan tool, command both engine cooling fans off. Check COOL FAN 1 fuse (30-amp) and COOL FAN 2 fuse (30-amp). If either fuse is blown, replace appropriate fuse and retest. If fuse blows again, repair short to ground in appropriate power feed circuit between fuse and cooling fan control unit. If fuses are okay, go to next step.
- Disconnect cooling fan control unit. Using DVOM, measure voltage at cooling fan control unit connector C1 terminal "D" and connector C2 terminal "B". If battery voltage is present at both terminals, go to next step. If battery voltage is not present on both terminals, repair open in appropriate circuit between underhood fuse block and cooling fan control unit.
- Using DVOM, measure voltage between cooling fan control unit connector C2 terminal "B" and connector C1 terminal "A". If battery voltage is present, go to next step. If battery voltage is not present, repair ground circuit (Black wire) between cooling fan control unit and ground.
- Reconnect cooling fan control unit. Using scan tool, perform 3 SPEED FAN test. Test one speed at a time, checking COOL FAN 1 fuse (30-amp) and COOL FAN 2 fuse (30-amp) at each speed. If neither fuse blows, go to next step. If COOL FAN 1 fuse blows, check power feeds to engine cooling fan 1 for short to ground. If COOL FAN 2 fuse blows, check power feeds to engine cooling fan 2 for short to ground.
- If either engine cooling fan runs when both fans are commanded off, go to next step. If neither fan runs when both fans are commanded off, go to step 8.
- Disconnect cooling fan control unit. Check for short to voltage in appropriate engine cooling fan power feed circuit. If problem was found, repair appropriate circuit. If problem was not found, replace cooling fan control unit.
- See COOLING FAN SYMPTOMS (2.2L) table or COOLING FAN SYMPTOMS (3.0L) table for appropriate circuit related to a specific failure. If problem is found, repair as necessary. If problem is not found, replace cooling fan control unit.
COOLING FAN SYMPTOMS (2.2L)
| Symptom | Probable Circuit |
|---|---|
| Cooling Fan 1 Inoperative, All Speeds | Open In White Wire Between Fan Control Unit & Cooling Fan Or Cooling Fan 1 |
| Cooling Fan 2 Inoperative, All Speeds | Open In Black Wire Between Cooling Fan 2 & Ground Or Cooling Fan 2 |
| Cooling Fan 1 & 2 Inoperative, Low Speed And/Or Cooling Fan 1 Inoperative, High Speed | Open In Light Blue Wire Between Cooling Fan Control Unit & Cooling Fan 1 Or Open In Gray Wire Between Cooling Fan Control Unit & Cooling Fan 2 |
| Cooling Fan 1 Inoperative & Cooling Fan 2 On High, Low Speed, & Cooling Fan Inoperative, Medium Speed | Short To Voltage In White Wire Between Cooling Fan Control Unit & Cooling Fan 1 |
| Cooling Fan 2 Inoperative, & Cooling Fan 1 on High, Low Speed | Short To Ground In White Wire Between Cooling Fan Control Unit & Cooling Fan 1 |
| Cooling Fan 1 Inoperative, Medium Speed | Open In Red Wire Between Cooling Fan Control Unit & Cooling Fan 1 |
| Cooling Fan 2 Inoperative, Medium Speed | Open In Black Wire Between Cooling Fan Control Unit & Cooling Fan 2 |
COOLING FAN SYMPTOMS (3.0L)
| Symptom | Probable Circuit |
|---|---|
| Cooling Fan 1 Inoperative, All Speeds | Open In Orange Wire Between Fan Control Unit & Cooling Fan Or Open In Black Wire Between Cooling Fan Contrl Unit & Cooling Fan |
| Cooling Fan 2 Inoperative, All Speeds | Open In Black Wire Between Cooling Fan 2 & Ground |
| Cooling Fan 1 and 2 Inoperative, Low Speed, & Cooling Fan 1 Inoperative, High Speed Or Cooling Fan 2 Inoperative, High Speed | Open In Yellow Wire Between Cooling Fan Control Unit & Cooling Fan 1 Or Open In Orange Wire Between Cooling Fan Control Unit & Cooling Fan 2 |
| Cooling Fan 2 Inoperative, & Cooling Fan 1 on High, Low Speed | Short To Ground In Orange Wire Between Cooling Fan Control Unit & Cooling Fan 1 |
| Cooling Fan 1 Inoperative, Medium Speed | Open In Black Wire Between Cooling Fan Control Unit & Cooling Fan 1 |
| Cooling Fan 2 Inoperative, Medium Speed | Open In Green Wire Between Cooling Fan Control Unit & Cooling Fan 2 |