Refer to
Cooling Fan Controls
.
Circuit Description
The relay coils are energized when the PCM completes the ground path. The PCM Output Driver Module (ODM) B output 1 is grounded for Fan 1 operation.
During Fan 1 operation the PCM supplies a ground path for the Fan 1 relay through ODM B Output 1. This closes the relay contacts and current flows through the relay and to the cooling fan. The primary cooling fan is grounded at the engine block.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
-
Stored Diagnostic Trouble Codes (That may not illuminate the Malfunction indicator Lamp) may enable the engine cooling fans. 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.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On Board Diagnostic (OBD) System Check performed? | -- | ||
Are any DTCs stored? | -- | Go to Applicable DTC | ||
3 |
Is Fan 1 ON? | -- | ||
4 | Select scan tool Misc. Tests, Relay Control function and command Fan 1 ON. Is Fan 1 ON? | -- | Go to Diagnostic Aids | |
Is the test light ON? | -- | |||
6 | Check for a blown fuse. Is the fuse blown? | -- | ||
7 |
Is the test light ON? | -- | ||
8 | Locate and repair open battery feed circuit in Fan 1 relay connector. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
9 |
Is Fan 1 running? | -- | ||
10 |
Is the test light ON? | -- | ||
11 |
Is the test light ON? | -- | ||
12 | Locate and repair open in Engine Cooling Fan Motor feed circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
13 | Locate and repair open in the Engine Cooling Fan Motor Ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
14 |
Is the test light ON? | -- | ||
15 |
Is the test light ON? | -- | ||
16 | Locate and repair open in the battery feed circuit to 85 in Fan 1 relay connector. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
17 | Locate and repair open in Fan 1 relay driver circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
18 |
Is the test light ON? | -- | ||
19 | Locate and repair short to ground in battery feed circuit to cavity 30 in Fan 1 relay connector. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
20 |
Is test light ON? | -- | ||
21 | Locate and repair short to ground in Engine Cooling Fan Motor feed circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
22 | Using scan tool monitor A/C pressure. Does scan tool indicate A/C pressure greater than the specified value? | 190 psi | ||
23 |
Is A/C pressure display at the specified value? | 0 psi | ||
24 | Locate and repair short to voltage in Engine Cooling Fan motor feed circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
25 | Replace A/C Pressure sensor. Is the action complete? | -- | -- | |
26 |
Important: : The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace PCM. Is the action complete? | -- | -- | |
27 | Replace Engine Cooling Fan motor. Is the action complete? | -- | -- | |
28 | Replace Fan 1 Relay. Is the action complete? | -- | -- | |
29 |
Is Engine Cooling Fan OFF? | -- | System OK |
