MODEL IDENTIFICATION
| Body Designation (1) | Model |
|---|---|
| "N" Body | Achieva, Grand Am & Skylark |
| (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.
3.1L
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 226°F (108°C) or more; if A/C high side pressure is 187 psi (12.9 kg/cm 2 ) or more and vehicle speed is less than 70 MPH; when Diagnostic Trouble Code (DTC) 14, 15 or 70 is stored; or when PCM is in back-up mode.
2.3L
Powertrain Control Module (PCM) energizes electric cooling fan when engine coolant temperature exceeds a certain value. PCM turns fan on when A/C is requested. If vehicle speed is greater than 35 MPH, PCM turns cooling fan off. PCM will turn on cooling fan regardless of vehicle speed if A/C refrigerant pressure or engine coolant temperature becomes excessive, or any Diagnostic Trouble Code (DTC) is stored.
Under certain high temperature conditions, cooling fan will continue to run-on for up to 7 minutes after ignition is off. Fan run-on occurs when Engine Coolant Temperature (ECT) sensor indicates greater than 212°F (100°C) and Intake Air Temperature (IAT) sensor indicates greater than 176°F (80°C); ECT sensor indicates greater than 234°F (112°C) and IAT indicates greater than 158°F (70°C); or ECT sensor indicates greater than 241°F (116°C).
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 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 |
|---|---|
| "L" & "N" Bodies | (1) On Bracket, Behind Right Strut Tower |
| (1) (Scheme 1) | |
| (1) | (Scheme 1) |
COOLING FAN RELAY LOCATION
Scheme 1
COOLING FAN CHART INDEX
| Application | Figure No. |
|---|---|
| 2.3L VIN D | (Scheme 2) & (Scheme 3). |
| 3.1L VIN M | (Scheme 4) - (Scheme 6). |
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 - 2.3L - VIN D
Cooling fan is controlled by Powertrain Control Module (PCM) based on inputs from Engine Coolant Temperature (ECT) sensor, Intake Air Temperature (IAT) sensor, A/C control switch, A/C refrigerant pressure sensor and Vehicle Speed Sensor (VSS). PCM grounds circuit No. 335, energizing cooling fan relay and turning on cooling fan. (Scheme 2) Cooling fan is turned on when engine coolant temperature is greater than 217°F (103°C), A/C clutch is requested or vehicle speed is less than 35 MPH.
Cooling fan is energized regardless of vehicle speed if a Diagnostic Trouble Code (DTC) is set, engine coolant temperature is greater than 239°F (115°C) or A/C refrigerant pressure is high.
Under certain high temperature conditions, cooling fan will continue to run after ignition is off. Fan run-on occurs when ECT sensor indicates greater than 212°F (100°C) and IAT sensor indicates greater than 176°F (80°C); ECT sensor indicates greater than 234°F (112°C) and IAT sensor indicates greater than 158°F (70°C); or ECT sensor indicates greater than 241°F (116°C).
Note. Test numbers refer to numbers on diagnostic chart. (Scheme 3)
- With fan relay activated, cooling fan driver should close, energizing cooling fan relay.
- Tests if fault is in wiring or fan relay connection.
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 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.
Scheme 2
Scheme 3
CHART C-12 - COOLING FAN CIRCUIT DIAGNOSIS - 3.1L - VIN M
Battery voltage is supplied to cooling fan relay by circuit No. 2 at cooling fan relay terminals No. 30 and 85. (Scheme 4) When Powertrain Control Module (PCM) grounds circuit No. 335, relay is energized and cooling fan is turned on. When engine is running, PCM will energize cooling fan if Diagnostic Trouble Code (DTC) 14, 15 or 70 is set, vehicle speed is less than 70 MPH, engine coolant temperature is greater than 226°F (108°C), A/C refrigerant pressure is greater than 187 psi (13.1 kg/cm 2 ), or PCM is in back-up mode.
Note. Test numbers refer to numbers on diagnostic charts. (Scheme 5)
- With diagnostic terminal grounded, cooling fan control driver will close, energizing fan control relay.
- If A/C pressure is greater than 300 psi (21.1 kg/cm 2 ) or circuit is open, fan runs whenever A/C is requested.
- With A/C compressor clutch engaged and A/C pressure sensor functioning properly, fan should come on when pressure exceeds about 200 psi (14.1 kg/cm 2 ). This signal should cause PCM to energize cooling fan relay. If referred to a C-10 chart, see the C-10 chart in the «A/C COMPRESSOR CLUTCH CONTROLS»(/buick/skylark/vii-1992-1998/remont/ac-compressor/#ac-compressor-clutch-controls) article.
- This will determine whether A/C pressure sensor, PCM or circuitry is faulty. NOTE: Test numbers refer to numbers on diagnostic charts. (Scheme 6)
- Battery voltage should be available at cooling fan relay terminals No. 30 and 85.
- Checks ability of PCM to ground circuit No. 335.
- If fan does not turn on at this point, circuit No. 409 is open or cooling fan motor is faulty.
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.
