Refer to
Cell 20: Engine Data Sensors-Cooling Fan Controls
.
Circuit Description:
Power for the fan motors is supplied through Maxi® Fuse 1in the Engine wiring Harness Junction Block 1. The cooling fan relays are energized when current flows from the PCM Bat Fuse in the Engine Wiring Harness Junction Block 1 and Fan #3 fuse in the Engine Wiring Harness Junction Block 2 through the relay coils to ground through the PCM. The Low Speed Fans control circuit is grounded for low speed fans operation. The Low Speed Fans control circuit and the High Speed Fans control circuit are both grounded for high speed fans operation.
During low speed fans operation the PCM supplies a ground path for the Fan Cont #1 Relay. This closes the Fan Cont #1 Relay contacts, allowing current to flow from the battery junction block through the relay contacts to the left engine cooling fan. During low speed operation, the ground path for the Engine Coolant Fan Motor 1 is through the Fan Cont #2 Relay and the Engine Coolant Fan Motor 2. The result is a series circuit with both cooling fans running at low speed.
During high speed cooling fan operation the PCM supplies a ground path for the Fan Cont #1 Relay. The PCM also supplies a ground path for Fan Cont #2 Relay and Fan Cont #3 Relay. This closes all three cooling fan relays. During high speed fans operation, both the Engine Coolant Fan Motor 1 and 2 are supplied current from the battery junction blocks and each cooling fan has its own ground path.
Diagnostic Aids
Check for the following conditions:
| • | Poor connection at the PCM, cooling fan relays, or cooling fan motors. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs and Wiring Repairs . |
| • | Damaged harness. Inspect the wiring harness for damage. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs and Wiring Repairs . |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
-
Stored diagnostic trouble codes may affect engine cooling fans operation. This diagnostic table may lead to improper diagnosis and replacement of good parts if diagnostic trouble codes are present.
-
Ambient temperature must be above 9°C (48°F) before the PCM will enable the cooling fans due to A/C request. The PCM will enable the cooling fans if A/C refrigerant pressure increases regardless of ambient temperature.
-
This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.
Step | Action | Value(s) | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain OBD System Check performed? | -- | ||||||||||||||
Are any PCM DTCs stored? | -- | Diagnose the PCM DTCs first | ||||||||||||||
3 |
Are the cooling fan(s) running? | -- | ||||||||||||||
4 |
Are both cooling fans running at low speed? | -- | ||||||||||||||
5 |
Are both fans running at high speed? | -- | ||||||||||||||
|
Important: : Ambient temperature must be above 9°C (48°F).
Are the cooling fans on? | -- | Go to Diagnostic Aids | ||||||||||||||
7 | View A/C Request on the scan tool. Does A/C Request on the scan tool display Yes? | -- | Go to Air Conditioning (A/C) Compressor Control Circuit Diagnosis | |||||||||||||
8 | Is either cooling fan running? | -- | ||||||||||||||
9 | Is the left cooling fan running? | -- | ||||||||||||||
10 |
Is the Engine Coolant Fan Motor 1 running? | -- | ||||||||||||||
11 | Remove the FAN CONT #2 Relay from the Engine Wiring Harness Junction Block. Is Engine Coolant Fan Motor 1 running? | -- | ||||||||||||||
12 | Locate and repair short to ground in CKT 532. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
13 |
Was a problem found? | -- | ||||||||||||||
14 |
Is Engine Coolant Fan Motor 2 running? | -- | ||||||||||||||
15 | Locate and repair short to battery positive voltage in circuit 532 and 504. If a problem is found repair as necessary. Refer to Wiring Repairs . Was a problem found? | -- | ||||||||||||||
16 |
Is the J 35616-200 test lamp on? | -- | ||||||||||||||
17 |
Is the action complete? | -- | -- | |||||||||||||
18 | Probe FAN CONT #1 Relay cavity C6 with a J 35616-200 test lamp connected to ground. Is the J 35616-200 test lamp on? | -- | ||||||||||||||
19 |
Blown fuse. If the fuse is blown, locate short circuit.
Is the action complete? | -- | -- | |||||||||||||
20 |
Is the J 35616-200 test lamp on? | -- | ||||||||||||||
21 |
Is the test lamp on? | -- | ||||||||||||||
22 |
Are both cooling fans running? | -- | ||||||||||||||
23 |
Was a problem found? | -- | ||||||||||||||
24 |
Was a problem found? | -- | ||||||||||||||
25 |
Is the J 35616-200 test lamp on? | -- | ||||||||||||||
26 | Locate and repair open in Low Speed Fans control circuit between the PCM and FAN CONT #1 Relay cavity B4. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
27 |
Is the J 35616-200 test lamp on? | -- | ||||||||||||||
28 | Connect a J 35616-200 test lamp between FAN CONT #2 Relay in Engine Wiring Harness Junction Block cavities C8 and B9. Is the J 35616-200 test lamp on? | -- | ||||||||||||||
29 |
Was a problem found? | -- | ||||||||||||||
30 |
Was a problem found? | -- | ||||||||||||||
31 |
Was a problem found? | -- | ||||||||||||||
32 | Using scan tool, view A/C Request. Does the scan tool display Yes? | -- | Go to Air Conditioning (A/C) Compressor Control Circuit Diagnosis | |||||||||||||
33 | Are both cooling fan(s) running at low speed? | -- | ||||||||||||||
34 | Remove FAN CONT #1 Relay from the Engine Wiring Harness Junction Block. Are the cooling fans running? | -- | ||||||||||||||
35 | Locate and repair short to voltage in CKT 409. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
36 | Using a J 35616-200 test lamp connected to battery positive voltage, probe FAN CONT #1 Relay cavity B4. Is the J 35616-200 test lamp on? | -- | ||||||||||||||
37 | Replace FAN CONT #1 Relay. Is the action complete? | -- | -- | |||||||||||||
38 |
Is the J 35616-200 test lamp on? | -- | ||||||||||||||
39 | Locate and repair short to ground in the FAN CONT #1 Relay control circuit. Refer to Wiring Repairs . Is action complete? | -- | -- | |||||||||||||
40 | Are both cooling fans running at high speed? | -- | ||||||||||||||
41 | View A/C Pressure on the scan tool. Does the scan tool display voltage less than the specified value? | 1.2V | ||||||||||||||
42 |
Is the Engine Coolant Fan Motor 2 running at high speed? | -- | ||||||||||||||
43 |
Was a problem found? | -- | ||||||||||||||
44 |
Does the scan tool display voltage near the specified value? | 0.0V | ||||||||||||||
45 | Probe the A/C refrigerant pressure signal circuit with a J 39200 connected to the A/C refrigerant pressure sensor ground. Does the J 39200 DMM display voltage near the specified value? | 0.0V | ||||||||||||||
46 | Probe the A/C refrigerant pressure sensor ground with a J 35616-200 test lamp to battery positive voltage. Is the J 35616-200 test lamp on? | -- | ||||||||||||||
47 | Probe the A/C refrigerant pressure sensor 5 volt reference circuit with a J 39200 DMM connected to the A/C refrigerant pressure sensor ground. Does the J 39200 DMM display voltage near the specified value? | 5.0V | ||||||||||||||
48 | Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement . Is the action complete? | -- | -- | |||||||||||||
49 | Locate and repair open or short to voltage in the A/C refrigerant pressure sensor ground circuit. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
50 | Locate and repair open or short to ground in the A/C refrigerant pressure sensor 5 Volt Reference B circuit. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
51 | Locate and repair short to voltage in the A/C refrigerant pressure signal circuit. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
52 |
Is Engine Coolant Fan Motor 2 running at high speed? | -- | ||||||||||||||
53 | Remove the Fan #3 Relay from the Engine Wiring Harness Junction Block 2. Is Engine Coolant Fan Motor 2 running at high speed? | -- | ||||||||||||||
54 | Locate and repair short to battery positive voltage in CKT 532. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
55 | Locate and repair short to battery positive voltage in CKT 504. Refer to Wiring Repairs . If a problem is found repair as necessary. Was a problem found? | -- | ||||||||||||||
56 |
Was a problem found? | -- | ||||||||||||||
57 |
Was a problem found? | -- | ||||||||||||||
58 |
Is the J 35616-200 test lamp on? | -- | ||||||||||||||
59 |
Is the J 35616-200 test lamp on? | -- | ||||||||||||||
60 |
Was a problem found? | -- | ||||||||||||||
61 |
Is the J 35616-200 test lamp on? | -- | ||||||||||||||
62 | Probe terminal A at Engine Coolant Fan Motor 1 connector with a J 35616-200 test lamp to battery positive voltage. Is the J 35616-200 test lamp on? | -- | ||||||||||||||
63 |
Is the action complete? | -- | -- | |||||||||||||
64 |
Is the J 35616-200 test lamp on? | -- | ||||||||||||||
65 | Locate and repair open in the ignition battery positive voltage circuit to FAN CONT #2 Relay. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
66 | Probe FAN CONT #2 Relay cavity C8 with a J 35616-200 test lamp connected to ground. Is the J 35616-200 test lamp on? | -- | ||||||||||||||
67 | Locate and repair open in battery positive voltage circuit to FAN CONT #2 Relay cavity C8. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
68 |
Was a problem found? | -- | ||||||||||||||
69 |
Was a problem found? | -- | ||||||||||||||
70 | Replace FAN CONT #2 Relay. Is the action complete? | -- | -- | |||||||||||||
71 |
Is the J 35616-200 test lamp on? | -- | ||||||||||||||
72 | Locate and repair open in battery positive voltage circuit to Fan #3 relay cavity B4. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
73 | Probe Fan 3 relay cavity B6 in the Engine Wiring Harness Junction Block with a J 35616-200 test lamp to battery positive voltage. Is the J 35616-200 test lamp on? | -- | ||||||||||||||
74 | Locate and repair open in circuit between Fan #3 cavity B6 and FAN CONT #2 Relay cavity B9 in the Underhood Electrical Center and ground. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
75 |
Was a problem found? | -- | ||||||||||||||
76 | Replace the Fan #3 relay in the Engine Wiring Harness Junction Block. Is the action complete? | -- | -- | |||||||||||||
|
Important: : The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | -- | ||||||||||||||
78 | Repair open in the Cool Fan 2 relay cavity 86 and Cool relay cavity 86 control circuit to PCM. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||||||
79 | Replace the Engine Coolant Fan Motor 1. Refer to Engine Cooling Fan Replacement . Is action complete? | -- | -- | |||||||||||||
80 | Replace the Engine Coolant Fan Motor 2. Refer to Engine Cooling Fan Replacement . Is the action complete? | |||||||||||||||
81 |
Are the cooling fans running? | -- | ||||||||||||||
82 |
Are both cooling fans running at low speed? | -- | ||||||||||||||
83 |
Are both cooling fans running at high speed? | -- | System OK |
