MODEL IDENTIFICATION
| Body Designation (1) | Model |
|---|---|
| "C" Body | Ninety Eight & Park Avenue |
| "H" Body | Bonneville, Eighty Eight & LeSabre |
| (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.
3.8L
High speed cooling fan is the left fan (fan No. 2) and low speed cooling fan is the right fan (fan No. 1). Powertrain Control Module (PCM) energizes low speed fan when engine coolant temperature is greater than 212°F (100°C), or when A/C is requested.
Left cooling fan will operate at a higher speed when high speed fan is requested. Cooling fan will continue to run about 45 seconds after A/C is turned off.
When low speed cooling fan is energized, PCM will delay high speed cooling fan for about 6 seconds. When A/C refrigerant pressure is greater than 210 psi (14.8 kg/cm 2 ), PCM will energize high speed cooling fan. PCM will also energize high speed cooling fan when engine coolant temperature is greater than 226°F (108°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 appropriate G-TESTS W/CODES article in the ENGINE PERFORMANCE section.
TESTS W/CODES - Park Avenue, Ninety Eight
TESTS W/CODES - LaSabre, Eighty Eight, Bonneville
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 |
|---|---|
| "C" & "H" Bodies | Bottom Of Fuse/Relay Block, On Right Rear Of Engine Compartment |
COOLING FAN RELAY LOCATION
COOLING FAN CHART INDEX
| Application | Figure No. |
|---|---|
| 3.8L VIN K, L & 1 | (Scheme 1) - (Scheme 5). |
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-12A - COOLING FAN CIRCUIT DIAGNOSIS 3.8L - VIN K, L & 1
Right cooling fan (fan No. 1) is a low speed fan. Left cooling fan (fan No. 2) is a low and high speed fan. Power for fan motor goes through a 40-amp fusible link to terminal No. 87 of fan relays. (Scheme 1) Fan relays are energized when a ground circuit is completed through Powertrain Control Module (PCM) quad-driver No. 4. PCM energizes right cooling fan (fan No. 1) relay through PCM terminal WD11 when Engine Coolant Temperature (ECT) sensor indicates 212°F (100°C) or when A/C is requested. PCM energizes left cooling fan (fan No. 2) relay if A/C refrigerant pressure reaches 210 psi (14.8 kg/cm 2 ) or ECT sensor indicates 226°F (108°C).
Scheme 1
CHART C-12A - COOLING FAN SYSTEM DIAGNOSIS (1 OF 4)
Note. Test numbers refer to numbers on diagnostic charts (Scheme 2)
Scheme 2
- Selecting Tech 1 miscellaneous tests, FAN 1, causes PCM to ground circuit No. 335. Right cooling fan (fan No. 1) should run.
- Selecting Tech 1 miscellaneous tests, FAN 2, allows control of circuit No. 473. Left cooling fan (fan No. 2) should run.
- When jumpering A/C head pressure switch harness connector, PCM should operate left cooling fan (fan No. 2) on high speed.
CHART C-12B - COOLING FAN ON AT ALL TIMES (2 OF 4)
Note. Test numbers refer to numbers on diagnostic chart. (Scheme 3)
Scheme 3
- Checks if circuit No. 335 is shorted to ground, which would keep relay closed at all times.
- Checks if circuit No. 473 is shorted to ground. If test light comes on, wire is shorted to ground. Continuing with chart diagnosis will isolate short.
- If test light is off after disconnecting PCM, ensure circuit No. 335 is not shorted to battery voltage. If circuit is not shorted to battery voltage, PCM is shorted internally.
- If test light is off after disconnecting PCM, ensure circuit No. 473 is not shorted to battery voltage. If circuit is not shorted to battery voltage, PCM is shorted internally.
CHART C-12C - NO LOW SPEED FAN (3 OF 4)
Note. Test numbers refer to numbers on diagnostic chart. (Scheme 4)
Scheme 4
- Checks for battery voltage at relay harness connector terminals No. 30 and 85.
- Jumpering relay terminals No. 30 and 87 by-passes relay, which should cause fans to run if fan motors and wiring are okay.
- Select Tech 1 miscellaneous tests, FAN 1. Turn fans on. PCM should ground circuit No. 335. At this point, test light should be on if PCM is good and circuit No. 335 is not open.
- Checks for battery voltage and ground to fan motor. Test light on at this point indicates a faulty fan motor connection or motor.
CHART C-12D - NO HIGH SPEED FAN (4 OF 4)
Note. Test numbers refer to numbers on diagnostic chart. (Scheme 5)
Scheme 5
- Battery voltage should be present at left fan relay (fan No. 2) terminals No. 30 and 85 with ignition on.
- Jumpering relay terminals No. 30 and No. 87 by-passes left fan relay (fan No. 2). If fan runs, fan relay is faulty.
- Checks circuit No. 473 back to PCM. If circuit No. 473 is okay, left fan relay (fan No. 2) is bad.
Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed-through wire insulation or a wire broken inside the wire insulation. Check PCM harness connector for backed-out terminals. Connect a DVOM between affected terminal and ground. Wiggle related wires and connectors while watching DVOM for a voltage reading change. Ensure ECT sensor is not mis-scaled. See Diagnostic Trouble Code (DTC) P0118 chart in the appropriate G-TESTS W/CODES article in the ENGINE PERFORMANCE section. Ensure engine cooling system functions properly.
TESTS W/CODES - Park Avenue, Ninety Eight
TESTS W/CODES - LaSabre, Eighty Eight, Bonneville
Cooling Fan Circuit Wiring Diagram. Scheme 6
See also:
• TESTS W/CODES
• COOLING FAN CHART INDEX