MODEL IDENTIFICATION
| Body Designation (1) | Model |
|---|---|
| "F" Body | Camaro & Firebird |
| (1) Body codes determined by fourth character of VIN code. | |
| (1) | Body codes determined by fourth character of VIN code. |
BODY CODE DESIGNATION
DESCRIPTION
The electric cooling fan is used for radiator and A/C condenser cooling. Cooling fan operates when A/C is on and when engine coolant temperature exceeds a specific value.
3.4L
Powertrain Control Module (PCM) controls electric cooling fan through a cooling fan relay. PCM will energize cooling fan relay when Engine Coolant Temperature (ECT) sensor indicates 228°F (109°C) or greater; A/C is requested and vehicle speed is less than 35 MPH; or when A/C is requested and A/C refrigerant pressure sensor indicates about 20 psi (1.4 kg/cm 2 ) or greater. PCM will energize cooling fan relay continuously when PCM is operating in back-up mode or any PCM Diagnostic Trouble Code (DTC) is stored. If vehicle speed is greater than 70 MPH, PCM will not energize cooling fan relay.
5.7L
Powertrain Control Module (PCM) monitors several inputs and controls 3 cooling fan relays to control fan operation. Vehicle uses 2 cooling fans. Both fans operate on either low or high speed simultaneously. Low fan speed operation is requested when engine coolant temperature is greater than 226°F (108°C). When PCM energizes cooling fans, minimum run time is 50 seconds.
High speed fan operation is requested when engine coolant temperature is greater than 235°F (113°C), or A/C head pressure is greater than 248 psi (17.4 kg/cm 2 ). When PCM energizes cooling fans, minimum run time is 30 seconds.
TROUBLE SHOOTING
Note. This article contains test charts which are part of General Motors Computerized Engine Controls. Only those charts required to test electric cooling fans are included. Other diagnostic information may be referenced while performing electric cooling fan diagnosis. For complete information on General Motors Computerized Engine Control systems, see the appropriate G-TESTS W/CODES article in the ENGINE PERFORMANCE section.
Trouble shoot cooling fan using appropriate C-12 charts provided. See COOLING FAN CHART INDEX table. For cooling fan relay location, see COOLING FAN RELAY LOCATION table.
| Application | Location |
|---|---|
| "F" Body | In Underhood Electrical Center, On Left Inner Fender Panel |
COOLING FAN RELAY LOCATION
COOLING FAN CHART INDEX
| Application | Figure No. | |
|---|---|---|
| 3.4L VIN S | (Scheme 1) - (Scheme 3) | |
| 5.7L VIN P | ||
| Early Production | (Scheme 4) - (Scheme 6) | |
| Late Production | (Scheme 7) - (Scheme 11) | |
COOLING FAN CHART INDEX
SCAN TESTER
A variety of information is transmitted through Data Link Connector (DLC) terminal "E" or "M" depending on engine. This data is transmitted at a high frequency which requires a Tech 1 scan tester for interpretation. Several scan testers are available for diagnostic work. Scan testers other than Tech 1 scan tester will function and provide information for diagnostic work; however, some charts will specify a Tech 1 scan tester. Failure to use a Tech 1 scan tester, when specified, may result in incorrect diagnosis of a system.
CHART C-12 - COOLING FAN CIRCUIT DIAGNOSIS - 3.4L - VIN S
Cooling fan is controlled by Powertrain Control Module (PCM) based on inputs from Engine Coolant Temperature (ECT) sensor, A/C control switches, A/C refrigerant pressure sensor and Vehicle Speed Sensor (VSS). When engine cooling temperature is greater than 228°F (109°C), or when A/C is requested and A/C refrigerant pressure sensor indicates high A/C pressure of about 240 psi (16.9 kg/cm 2 ), PCM grounds circuit No. 335. (Scheme 1) This energizes cooling fan relay and turning on cooling fan. When cooling fan is turned on, PCM will keep fan energized at least 30 seconds or until vehicle speed exceeds 70 MPH. If DTC 14 or 15 is set or PCM is in back-up mode, fan will run continuously.
Scheme 1
Note. Test numbers refer to numbers on diagnostic chart. (Scheme 2)
Scheme 2
Scheme 3
- 1) With Data Link Connector (DLC) diagnostic terminal grounded, cooling fan control driver will close, energizing cooling fan relay.
- 2) If A/C refrigerant pressure is greater than 240 psi (16.9 kg/cm 2 ) or A/C refrigerant pressure sensor circuit is open, cooling fan comes on whenever A/C is requested.
- 3) With A/C compressor clutch engaged and A/C refrigerant pressure sensor functioning properly, cooling fan should energize when A/C refrigerant pressure is greater than 20 psi (1.4 kg/cm 2 ). When ambient temperatures are very cold, cooling fan will remain off. If referred to a C-10 chart, see the appropriate C-10 chart in the «A/C COMPRESSOR CLUTCH CONTROLS»(/chevrolet/camaro/iv-1992-1998/remont/ac-compressor/#ac-compressor-clutch-controls) article.
- 4) Determines whether A/C refrigerant pressure sensor, PCM or circuitry is faulty. NOTE: Test numbers refer to numbers on diagnostic chart. (Scheme 3)
- 1) Battery voltage should be available at circuits No. 402 and 541 of cooling fan relay when ignition is on.
- 2) Checks ability of PCM to ground circuit No. 335. Malfunction Indicator Light (MIL) should also be flashing at this point. If MIL is not flashing, see the «TESTS W/CODES - 3.4L»(/chevrolet/camaro/iv-1992-1998/remont/testing-diagnostics/#engine-controls-tests-wcodes-34l) article in the ENGINE PERFORMANCE section.
- 3) If cooling fan does not turn on at this point, circuit No. 150 or 409 is open, or cooling fan motor is faulty.
Diagnostic Aids
If an overheating condition is suspected, check if it is caused by an actual boilover. If gauge or light indicates an overheat condition and boilover is not evident, inspect gauge circuit for malfunction.
If vehicle is overheating and gauge or light indicates so but cooling fan is not coming on, check Engine Coolant Temperature (ECT) sensor temperature using a Tech 1 scan tester. ECT sensor may have shifted out of calibration and should be replaced. If engine is overheating and cooling fan is on, check cooling system.
CHART C-12 - COOLING FAN CIRCUIT DIAGNOSIS - 5.7L - VIN P (NON A/C & EARLY PRODUCTION A/C)
Powertrain Control Module (PCM) controls cooling fans based on various inputs. Battery voltage is supplied to terminal D1 of primary fan relay and terminal F4 of secondary fan relay. (Scheme 4) Ignition voltage is supplied to terminal D5 of primary fan relay and terminal F2 of secondary fan relay. Grounding circuit No. 335 (relay terminal D2) will energize primary cooling fan and supply battery voltage to primary cooling fan motor.
Grounding circuit No. 473 (relay terminal F5) will energize secondary cooling fan and supply battery voltage to secondary cooling fan motor. When certain Diagnostic Trouble Codes (DTC) are set, PCM will turn on both fans. Non-A/C vehicles are equipped with a primary cooling fan only. A/C-equipped vehicles have primary and secondary cooling fans. A/C-equipped vehicles have manual A/C-heater (C60) system.
Scheme 4
Note. Test numbers refer to numbers on diagnostic chart. (Scheme 5)and (Scheme 6).
Scheme 5
Scheme 6
- With output/field service enable terminal grounded, cooling fan control driver(s) will close, energizing fan control relays.
- Engine coolant temperature must be less than 212°F (100°C) to perform this step. Cooling fans should come on anytime A/C system is operating.
- Comparing Tech 1 scan tester A/C refrigerant pressure and manifold gauge set pressure will determine if A/C refrigerant pressure sensor is out of range. An out-of-range A/C refrigerant pressure sensor can cause cooling fans to operate at wrong times.
If an overheating condition is suspected, check if it is caused by an actual boilover. If gauge or light indicates an overheat condition and boilover is not evident, inspect gauge circuit for malfunction.
If vehicle is overheating and gauge or light indicates so but cooling fan is not coming on, check Engine Coolant Temperature (ECT) sensor temperature using a scan tester. ECT sensor may have shifted out of calibration and should be replaced. If engine is overheating and cooling fan is on, check cooling system. PCM will command primary cooling fan on at 226°F (108°C) and off at 221°F (105°C). Secondary cooling fan will turn on at 235°F (113°C) and off at 230°F (110°C).
CHART C-12 - COOLING FAN CIRCUIT DIAGNOSIS - 5.7L - VIN P (LATE PRODUCTION A/C)
Cooling fans are controlled by Powertrain Control Module (PCM) based on various inputs. Ignition voltage is supplied to all 3 cooling fan coils on circuit No. 541. (Scheme 7) PCM controls cooling fan relay No. 1 by providing ground path through circuit No. 335. PCM controls cooling fans No. 2 and 3 together by providing ground path through circuit No. 473. When cooling fan relay No. 1 is energized, cooling fans are connected in series and operate together at low speed. When all 3 relays are energized, fans are connected in parallel and operate together at high speed. When certain Diagnostic Trouble Codes (DTC) are set, PCM will enable cooling fans.
Scheme 7
Note. Test numbers refer to numbers on diagnostic charts. (Scheme 8)- (Scheme 10).
Scheme 8
Scheme 9
Scheme 10
Scheme 11
- 1) Cooling fans should come on anytime A/C system is operating.
- 2) Comparing Tech 1 scan tester pressure and manifold gauge set pressure will determine if A/C refrigerant pressure sensor is out of range. An out-of-range pressure sensor can cause cooling fans to operate at wrong times. NOTE: Test number refers to number on diagnostic chart. (Scheme 11)
- 1) It may be necessary to raise and support vehicle and observe cooling fans from under vehicle during testing. Both fans should operate at low speed when FAN CTRL PCM A11 is activated. Both fans should operate at high speed when FAN CTRL PCM A10 is activated.
If an overheating condition is suspected, check if it is caused by an actual boilover. If gauge or light indicates an overheat condition and boilover is not evident, inspect gauge circuit for malfunction.
If vehicle is overheating and gauge or light indicates so but cooling fan is not coming on, check Engine Coolant Temperature (ECT) sensor temperature using a scan tester. ECT sensor may have shifted out of calibration and should be replaced. If engine is overheating and cooling fan is on, check cooling system. PCM will command low speed cooling fan operation on at 226°F (108°C) and off at 221°F (105°C). High speed cooling fan operation turns on at 235°F (113°C) and turns off at 230°F (110°C).
