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Home >> Chevrolet >> 2007 >> Optra LT, Automatic >> Repair and Diagnosis (Single Page) >> Engine Mechanical >> Cooling System (Mechanical) >> Engine Cooling >> Diagnostic Information and Procedures >> Cooling Fan Circuit Diagnosis (2.0L) >> Test Description

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 4:  This step, along with step 5, inspects the ability of the ECM to operate the cooling fans.
  2. 8:  This step, along with step 9, inspects the ability of the ECM to operate the cooling fans in response to A/C pressure readings.
  3. 16:  After confirming battery voltage and the ECM supplying a ground to the coil side of the cooling fan relay A, by jumpering connector terminals 30 and 87 it will be determined if the relay is at fault or a wiring condition is present.
  4. 31:  This step inspects for the presence of battery voltage to the main cooling fan when the A/C is ON. If battery voltage is present and the cooling fans are not operating, the condition is in the ground side of the cooling fan circuit.
  5. 37:  By directly grounding the ECM connector terminals K28 and K12, the main and auxiliary cooling fans should run at high speed.
Step Action Yes No
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Inspect the instrument panel (I/P) fuse block fuse F2.
  2. Replace the fuse as needed.
Is the fuse OK?		 Go to Step 3  Go to Diagnostic Aids
3
  1. Inspect the engine fuse block fuse Ef6.
  2. Replace the fuse as needed.
Is the fuse OK?		 Go to Step 4  Go to Diagnostic Aids
4 
  1. Turn the ignition OFF.
  2. Turn the A/C switch OFF.
  3. Connect a scan tool to the data link connector (DLC).
  4. The cooling fans should run at low speed when the coolant temperature reaches 97°C (207°F).
Do the cooling fans run at low speed?		 Go to Step 5  Go to Step 10 
5
  1. Turn the ignition OFF.
  2. Turn the A/C switch OFF.
  3. Connect a scan tool to the DLC.
  4. Start the engine.
  5. The cooling fans should run at high speed when the coolant temperature reaches 101°C (214°F).
Do the cooling fans run at high speed?		 Go to Step 6  Go to Step 33 
6
  1. Turn the ignition OFF.
  2. Start the engine.
  3. Turn the A/C switch ON.
Does the A/C compressor clutch engage?		 Go to Step 8  Go to Step 7 
7
  1. Diagnose the A/C compressor clutch circuit.
  2. Repair the A/C compressor clutch circuit as needed.
  3. Start the engine.
  4. Turn the A/C switch ON.
Does the A/C compressor clutch engage?		 Go to Step 8  -
8  Do the cooling fans run at low speed? Go to Step 9  Go to Step 31 
9
  1. Turn the ignition OFF.
  2. Connect the A/C pressure gages.
  3. Start the engine.
  4. Turn the A/C switch ON.
  5. The cooling fans should run at high speed when the high side A/C pressure reaches 1 882 kPa (273 psi).
Do the cooling fans run at high speed?		 Go to Step 10  -
10
  1. Turn the ignition OFF.
  2. Connect a scan tool to the DLC.
  3. The coolant temperature should be above 97°C (207°C).
  4. Disconnect the main cooling fan connector.
  5. Turn the ignition ON.
  6. Connect a test light between the main cooling fan connector terminal 2 and ground.
Is the test light ON?		 Go to Step 11  Go to Step 12 
11
  1. Turn the ignition OFF.
  2. Connect a scan tool to the DLC.
  3. The coolant temperature should be above 97°C (207°C).
  4. Disconnect the main cooling fan connector.
  5. Connect a test light between the main cooling fan connector terminal 1 and ground.
Is the test light ON?		 Go to Step 28  Go to Step 17 
12
  1. Turn the ignition OFF.
  2. Disconnect the cooling fan relay low.
  3. Connect a test light between the cooling fan relay low connector terminal 85 and ground.
  4. Turn the ignition ON.
Is the test light ON?		 Go to Step 13  Go to Step 24 
13
  1. Turn the ignition OFF.
  2. Connect the cooling fan relay low.
  3. Disconnect the engine control module (ECM) white connector.
  4. Connect a fused jumper between the ECM connector terminal K28 and ground.
  5. Turn the ignition ON.
Do the cooling fans run at low speed?		 Go to Step 30  Go to Step 14 
14 Inspect for an open wire between the low speed cooling fan relay connector terminal 86 and the ECM connector terminal K28.
Is the condition found?		 Go to Step 25  Go to Step 15 
15
  1. Turn the ignition OFF.
  2. Disconnect the cooling fan relay low.
  3. Connect a test light between the cooling fan relay low connector terminal 30 and ground.
Is the test light ON?		 Go to Step 16  Go to Step 23 
16  Connect a fused jumper between the cooling fan relay low connector terminals 30 and 87.
Do the cooling fans run at low speed?		 Go to Step 26  Go to Step 17 
17
  1. Disconnect the cooling fan control relay.
  2. Connect a fused jumper between the cooling fan relay low connector terminals 30 and 87.
  3. Connect a fused jumper between the cooling fan control relay connector terminals 30 and 87.
Do the cooling fans run at low speed?		 Go to Step 27  Go to Step 18 
18 Inspect the wire between the cooling fan relay low connector terminal 87 to the main cooling fan connector terminal 2 for an open.
Is the condition found?		 Go to Step 22  Go to Step 19 
19 Inspect the wire between the main cooling fan connector terminal 1 and the cooling fan control relay connector terminal 30 for an open.
Is the condition found?		 Go to Step 22  Go to Step 20 
20 Inspect the wire between the cooling fan control relay connector terminal 87A and the auxiliary cooling fan connector terminal 2 for an open.
Is the condition found?		 Go to Step 22  Go to Step 21 
21 Inspect for an open wire between the auxiliary cooling fan connector terminal 1 and ground.
Is the condition found?		 Go to Step 22  Go to Step 29 
22 Repair the open wire as needed.
Is the repair complete?		 System OK -
23 Repair the open between the cooling fan relay low connector terminal 30 and the fuse Ef6.
Is the repair complete?		 System OK -
24 Repair the open between the cooling fan relay low connector terminal 86 and the ignition switch.
Is the repair complete?		 System OK -
25 Repair the open wire between the cooling fan relay low connector terminal 85 and the ECM connector terminal K28.
Is the repair complete?		 System OK -
26 Replace the cooling fan relay low. Refer to Relay Replacement (Within an Electrical Center) .
Is the replacement complete?		 System OK -
27 Replace the cooling fan control relay. Refer to Relay Replacement (Within an Electrical Center) .
Is the replacement complete?		 System OK -
28 Replace the main cooling fan. Refer to Cooling Fan Replacement - Electric .
Is the replacement complete?		 System OK -
29 Replace the auxiliary cooling fan. Refer to Cooling Fan Replacement - Electric .
Is the replacement complete?		 System OK -
30 Replace the ECM.
Is the replacement complete?		 System OK -
31 
  1. Turn the ignition OFF.
  2. Disconnect the main cooling fan connector.
  3. Connect a test light between the main cooling fan connector terminal 2 and ground.
  4. Turn the A/C switch ON.
  5. Start the engine.
Is the test light ON?		 Go to Step 32  Go to Step 12 
32
  1. Turn the ignition OFF.
  2. Connect a test light between the main cooling fan connector terminal 1 and battery positive.
  3. Turn the A/C switch ON.
  4. Start the engine.
Is the test light ON?		 Go to Step 28  Go to Step 17 
33
  1. Turn the ignition OFF.
  2. Disconnect the cooling fan relay high.
  3. Connect a test light between the cooling fan relay high connector terminal 86 and ground.
  4. Turn the ignition ON.
Is the test light ON?		 Go to Step 34  Go to Step 44 
34
  1. Turn the ignition OFF.
  2. Connect a test light between the cooling fan relay high connector terminal 30 and ground.
Is the test light ON?		 Go to Step 35  Go to Step 45 
35
  1. Disconnect the cooling fan control relay.
  2. Connect a test light between the cooling fan control relay connector terminal 85 and ground.
  3. Turn the ignition ON.
Is the test light ON?		 Go to Step 36  Go to Step 46 
36
  1. Turn the ignition OFF.
  2. Connect a test light between the cooling fan control relay connector terminal 87 and battery positive.
Is the test light ON?		 Go to Step 37  Go to Step 47 
37 
  1. Connect the main cooling fan connector.
  2. Connect the cooling fan relay high.
  3. Connect the cooling fan control relay.
  4. Disconnect the ECM connector.
  5. Connect a fused jumper between the ECM connector terminal K28 and ground.
  6. Connect a fused jumper between the ECM connector terminal K12 and ground.
  7. Turn the ignition ON.
Do the cooling fans run at high speed?		 Go to Step 30  Go to Step 38 
38
  1. Turn the ignition OFF.
  2. Inspect for an open wire between the cooling fan relay high connector terminal 85 and the ECM connector terminal K12.
Is the condition found?		 Go to Step 22  Go to Step 39 
39
  1. Disconnect the cooling fan relay high.
  2. Connect a test light between the cooling fan relay high connector terminal 87 and battery positive.
Is the test light ON?		 Go to Step 40  Go to Step 48 
40
  1. Disconnect the ECM connector.
  2. Connect a fused jumper between the ECM connector terminal K12 and ground.
  3. Disconnect the cooling fan relay high.
  4. Connect a test light between the cooling fan control relay connector terminal 86 and battery positive.
Is the test light ON?		 Go to Step 41  Go to Step 49 
41
  1. Connect the cooling fan control relay.
  2. Connect a fused jumper between the ECM connector terminal K12 and ground.
  3. Disconnect the cooling fan relay high.
  4. Connect a fused jumper between the cooling fan relay high connector terminals 30 and 87.
  5. Disconnect the low speed cooling fan relay.
  6. Connect a fused jumper between the low speed cooling fan relay connector terminals 30 and 87.
  7. Turn the ignition ON.
Do the cooling fans run at high speed?		 Go to Step 43  Go to Step 42 
42
  1. Turn the ignition OFF.
  2. Connect a fused jumper between the ECM connector terminal K12 and ground.
  3. Disconnect the cooling fan control relay.
  4. Connect a fused jumper between the cooling fan control relay connector terminals 30 and 87.
  5. Connect a fused jumper between the low speed cooling fan relay connector terminals 30 and 87.
  6. Turn the ignition ON.
Do the cooling fans run at high speed?		 Go to Step 27  -
43 Replace the cooling fan relay high. Refer to Relay Replacement (Within an Electrical Center) .
Is the replacement complete?		 System OK -
44 Repair the open wire between the cooling fan relay high connector terminal 86 and the ignition switch.
Is the repair complete?		 System OK -
45 Repair the open wire between the cooling fan relay high connector terminal 30 and the battery.
Is the repair complete?		 System OK -
46 Repair the open wire between the cooling fan control relay connector terminal 85 and the ignition switch.
Is the repair complete?		 System OK -
47 Repair the open wire between the cooling fan control relay connector terminal 87 and ground.
Is the repair complete?		 System OK -
48 Repair the open wire between the cooling fan relay high connector terminal 87 and the auxiliary cooling fan connector terminal 2.
Is the repair complete?		 System OK -
49 Repair the open wire between the cooling fan control relay connector terminal 85 and the ECM connector terminal K12.
Is the repair complete?		 System OK -
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