Engine Cooling Fan Oldsmobile Toronado Trofeo

APPLICATION

ELECTRIC COOLING FAN APPLICATIONS

DESCRIPTION

All FWD and some RWD vehicles use an electric cooling fan. This fan is used for engine and A/C condenser cooling and operates when A/C is on and if engine overheats.

OPERATION

All electric cooling fans operate when engine coolant temperature exceeds a certain value. The ECM completes ground path for the cooling fan relay. Relay contacts then close and complete circuit between fusible link and fan motor. When the engine cools, the switch opens and fan stops. If coolant sensor fails, the ECM will command constant fan operation.

A/C equipped vehicles have a separate signal line to the ECM for fan control. When A/C control switch is "ON", and A/C system low pressure switch is closed, the ECM receives a signal on this line and turns on the cooling fan. The compressor clutch does not have to engage for ECM to turn fan on.

On some models, when engine is off, ECM may turn on the fan relay and run fan for up to 7 minutes. This occurs if hot conditions were present while engine was running. Hot conditions are based on Manifold Absolute Temperature (MAT) signal to ECM, coolant temperature and time from start.

TROUBLE SHOOTING (3.8L)

Note. This article contains test charts that are part of General Motors Computerized Engine Controls. Only those charts required to test electric cooling fans are included. Other diagnostic codes may appear while performing electric cooling fan diagnosis. For complete information on General Motors Computerized Engine Control systems, see appropriate article in ENGINE PERFORMANCE section.

See appropriate CHART & Fig. for trouble shooting & diagnosis.

CHART C-12A, FAN FUNCTIONAL CHECK (3.8L)

System uses 2 cooling fans and 3 relays. The ECM energizes the low speed relay (fan relay "G") through circuit No. 535 when coolant temperature exceeds 214°F (101°C). The low speed relay will also be energized when requested by the BCM based on A/C high side temperature, BCM data BD27, which exceeds 122°F (50°C).

The ECM will energize all 3 relays for high speed fan(s) when coolant temperature exceeds 226°F (108°C), or when requested by BCM based on A/C high side temperature, BCM data BD27, which exceeds 149°F (65°C).

Note. Test numbers refer to test numbers on diagnostic charts.

Scheme 1

1. Codes EO14 or EO15 could mean coolant system or sensor operation is not normal. Cooling fan(s) operation CANNOT be checked accurately.
2. ECM output EO09 grounds low speed relay through the ECM for 3 seconds on and 3 seconds off. Low speed fan should be on for 3 seconds, and off for 3 seconds.
3. Grounding ALDL terminal "A" to "B" will cause ECM to ground fan relays "G", "C" and "D". Cooling fans should run at high speed.

CHART C-12B, NO LOW SPEED COOLING FAN (3.8L)

Note. Test numbers refer to test numbers on diagnostic charts.

Scheme 2

1. Test light should be on because harness terminal No. 2 has battery voltage with ignition on. Terminal No. 4 has battery voltage at all times.
2. Test light on validates circuit through both cooling fan motors, relay "C" and ground connections.
3. Jumper harness terminals No. 1 and 4 of relay "G" and remove relay "C", then touch a test light to terminal No. 1 of relay "C" harness. If test light is on, relay "C" is faulty. If test light is off, circuit No. 532, 533 or pusher cooling fan is faulty.
4. Test light on validates all circuits. If test light is on, relay "C" is faulty. If test light is off, connection at puller cooling fan or cooling fan is faulty.

CHART C-12C-1, NO HIGH SPEED PULLER FAN (3.8L)

Note. Test numbers refer to test numbers on diagnostic charts.

Scheme 3

1. Test light should be on because harness terminal No. 5 has battery voltage with ignition on. Terminal No. 1 has battery voltage at all times.
2. Test light should be on for 3 seconds and off for 3 seconds as EO10 cycles cooling fan.
3. Jumpering harness terminals No. 1 and 4 by-passes relay. If cooling fan runs, relay is faulty.
4. Cycling of test light proves circuits No. 533 and 804 are okay and cooling fan motor is faulty.

CHART C-12C-2, NO HIGH SPEED PUSHER FAN (3.8L)

Note. Test numbers refer to test numbers on diagnostic charts.

Scheme 4

1. Test light should be on because harness terminal No. 2 has battery voltage when ignition is on. Terminal No. 4 has battery voltage at all times.
2. Test light on validates circuit through both cooling fan motors, relay "C" and ground connections.
3. Jumper harness terminals No. 1 and 4 of relay "G" and remove relay "C", then touch a test light to terminal No. 1 of relay "C" harness. If test light is on, relay "C" is faulty. If test light is off, circuit No. 532, 533 or pusher cooling fan is faulty.
4. Test light on validates all circuits. If test light is on, relay "C" is faulty. If test light is off, a fault exists in ground circuit No. 804.

CHART C-12D, FAN(S) ON ALL TIMES (3.8L)

Note. Test numbers refer to test numbers on diagnostic charts.

1. Cooling fans should NOT run when key is off.
2. Cooling fans should NOT run when engine is off.
3. Disconnecting the A/C high side temperature sensor will remove the BCM and/or ECM request due to A/C high side temperature.
4. Defines cooling fan operation based on coolant temperature only.

Diagnostic Aids

Cooling fan should be off if coolant temperature is below 208°F (98°C) and A/C high side temperature is below 122°F (50°C).

Note. On-board diagnostics may assist in diagnosing BD21 coolant temperature sensor, and BD27 A/C high side temperature sensor.

Disconnecting A/C high side temperature sensor should result in a BD27 reading less than -30°F (-34°C). If not, see B111 diagnostic code.

Disconnecting coolant temperature sensor should cause BD21 reading less than -30°F (-34°C). If not, see diagnostic code E014 or E015. For complete diagnostic code information, see appropriate article in ENGINE PERFORMANCE section.

BD27 should read approximately 122°F (50°C) when A/C system high side pressure is approximately 160 psi (11 kg/cm 2 ).

Scheme 5

SYSTEM OPERATION

Note. See wiring diagram at end of this article for system operation and testing.

Two cooling fans are used. The Electronic Control Module (ECM) controls 3 relays for fan operation. Two modes of fan operation exist, series mode and parallel mode. In series mode (low speed), one cooling fan relay is energized by the ECM to complete the ground. This connects the cooling fan in series with usage of another cooling fan relay. This operates pusher cooling fan (located in front of radiator) and puller cooling fan (located behind radiator) on the low speed. During parallel mode, all 3 cooling fan relays are energized by the ECM, and both cooling fans operate on high speed. Cooling fan operates only with ignition on.

During series mode (low speed), the Body Computer Module (BCM) sends a signal to ECM to operate cooling fans when A/C high side temperature exceeds 140°F (60°C) and turns off fans when temperature is less than 122°F (50°C). The BCM will also request ECM to operate cooling fans when following conditions exist: vehicle speed is less than 20 mph, A/C clutch is energized and outside temperature is greater than 113°F (45°C) or A/C high side temperature is greater than 122°F (50°C). The ECM will activate cooling fans at low speed when coolant temperature is greater than 212°F (100°C) and turn fans off when coolant temperature is less than 208°F (98°C). The ECM grounds the circuit to cooling fan relay "B". Cooling fan relay "B" is energized and connects both cooling fans in series for fan operation.

During parallel mode (high speed), the Body Computer Module (BCM) sends a signal to ECM to operate cooling fans. Fans will operate when A/C high side temperature is greater than 158°F (70°C) or A/C high side temperature sensor fails and diagnostic code B111 exists and A/C clutch engagement exists. The BCM will request that cooling fans be turned off when A/C high side temperature is less than 138°F (59°C).

The ECM will also operate cooling fans at high speed when coolant temperature is greater than 225°F (108°C) or coolant temperature sensor failure exists and diagnostic codes E014 and E015 exist. Cooling fans will switch to low speed operation when coolant temperature is less than 222°F (106°C). Cooling fans operate at high speed when Dark Green wire to cooling fan relay "B" and Light Green/Black wire to cooling fan relay "C" is grounded. When cooling fan relay "B" is grounded, this energizes the relay for the pusher cooling fan operation. When cooling fan relay "C" is grounded, this energizes cooling fan relay "C" and "D". Current is passed through cooling fan relay "D" to the puller cooling fan.

TROUBLE SHOOTING HINTS

Note. Ensure no diagnostic codes exist or diagnostic system can be entered prior to testing. For diagnostic code information, see appropriate article in ENGINE PERFORMANCE section. manual. Check the following prior to performing system check.

1. If cooling fans do not operate, check fusible link by operating the horns. If no operation exists, check Rust colored fusible link at power junction block located at right corner of engine compartment.
2. If A/C compressor clutch operation is defective, check cooling fan fuse No. 1 in relay center. Relay center is located at left front corner of engine compartment.
3. If both cooling fans operate in low speed with ignition off, check for short to power circuit on Black/White wire from cooling fan relay "B" to pusher fan. If wiring circuit is okay, replace cooling fan relay.
4. If both cooling fans operate in high speed but not in low speed, check Black/Pink wire from cooling fan relay "C" to cooling fan relay "D" for an open circuit. Also check continuity between Black/Pink wire terminals of cooling fan relay "C".

SYSTEM CHECK

1. Ensure no diagnostic codes exist. For diagnostic code information and ECM overrides, see appropriate article in ENGINE PERFORMANCE section.
2. If no codes exist, proceed to next step. If codes exist, correct as necessary.
3. Enter ECM overrides and select ES08 (cooling fan output override mode). System operation can be checked by using the cooler and warmer buttons of climate control. Cooler button controls cooling fan output No. 1 (ECM terminal 2A11) and warmer button controls cooling fan output No. 2 (ECM terminal 2B8).
4. Each depression of the button changes cooling fan operation. Zero (0) indicates that no operation exists (de-energized) and 1 indicates that operation exists (energized).
5. Operate cooler and warmer buttons of climate control using proper procedure to check system operation. See «SYSTEM CHECK»(/oldsmobile/toronado-trofeo/1990-1990/remont/cooling-fan/#engine-cooling-fan) table. If cooling fan did not operate correctly, perform system diagnosis test. See SYSTEM DIAGNOSIS in this article.

Note. Pusher fan is located in front of the radiator and puller fan is located behind the radiator.

SYSTEM CHECK

Both Fans Inoperative

See TEST A - BOTH COOLING FANS INOPERATIVE under SYSTEM TESTING in this article.

Pusher Fan Inoperative

See TEST B - PUSHER FAN INOPERATIVE under SYSTEM TESTING in this article.

Low Speed Okay & No High Speed On Pusher Fan

See TEST C - NO HIGH SPEED ON PUSHER FAN under SYSTEM TESTING in this article.

Low Speed Okay & No High Speed On Puller Fan

See TEST D - NO HIGH SPEED ON PULLER FAN under SYSTEM TESTING in this article.

Low Speed Okay & No High Speed On Both Fans

See TEST E - NO HIGH SPEED ON BOTH FANS under SYSTEM TESTING in this article.

Continuous Low Speed With Ignition Off

Check for short to power circuit on Black/White wire from cooling fan relay "B" to pusher cooling fan (front). If wiring circuit is okay, replace cooling fan relay "B".

Continuous Low Speed With Ignition On

Check Dark Green wire (circuit 535) for short to ground. If no ground exists, check ECM. For ECM checking procedure, see appropriate article in ENGINE PERFORMANCE section.

No Low Speed & High Speed Okay

Check Black/Pink wire from cooling fan relay "C" to cooling fan relay "D" for an open circuit. Check continuity between Black/Pink wire terminals of cooling fan relay "C".

Puller Fan Operates Continuously With Ignition On Or Off

Check Black/Pink wire (circuit 533) for short to battery. If no short exists, replace cooling fan relay "D".

Puller Fan Operates Continuously With Ignition On

Check Light Green/Black wire (circuit 536) for short to ground. If no ground exists, check ECM. For ECM checking procedure, see appropriate article in ENGINE PERFORMANCE section.

Puller Fan Inoperative

Check Black/Pink wire (circuit 533) between connector (S161) and puller fan for open circuit. Check Black wire (circuit 804) between puller fan and connector (S112) for an open. Check connection at puller fan.

No Low Speed & Pusher Fan Operates At High Speed When In ES08

Check Black/Pink wire (circuit 533) between pusher fan and cooling fan relay "C" for short to ground. If no short exists, replace cooling fan relay "C".

Test A - Both Cooling Fans Inoperative (4.5L)

1. If cooling fans do not operate, check fusible link by operating the horns. If no operation exists, check Rust colored fusible link at power junction block located at right front corner of engine compartment. If fusible link is defective, check for short in power circuit. Also check Red wire circuit to cooling fan relay "D" and ground circuit (Black wire) from cooling fan relays to ground.
2. Remove cooling fan relay "B" from under-hood relay center. Relaycenter is located in left front corner of engine compartment behind the headlight. Turn ignition on. Check for battery voltage at Red/White wire terminal of relay connector. If voltage exists, proceed to next step. If no voltage exists, check coolant fan fuse No. 1 and Red/White wire (circuit 850) for opens. Repair as necessary.
3. If voltage exists, check wiring to both cooling fans and wiring terminals. Repair as necessary. If wiring is okay, check Dark Green wire (between cooling fan relay "B" and ECM) and Light Green wire (between cooling fan relay "C" and ECM) for open circuit.
4. Repair circuits as necessary. If both wiring circuits are okay, check ECM. For ECM checking procedure, see appropriate article in ENGINE PERFORMANCE section.

Test B - Pusher Fan Inoperative (4.5L)

1. Remove cooling fan relay (center position "B") from under-hood relay center. Relay center is located in left front corner of engine compartment behind the headlight.
2. Turn ignition on. Check for battery voltage at Red/White wire and Red wire terminals of relay connector. If voltage exists at both terminals, proceed to next step. If no voltage exists, check coolant fan fuse No. 1 and Red/White wire (circuit 850) and Red wire (circuit 2) for opens. Repair as necessary.
3. If voltage exists, enter ECM overrides and select ES08. Adjust diagnostic display to 10. Connect test light at Red/White wire and Dark Green wire terminals of cooling fan relay (center position "B") at under-hood relay center.
4. Turn ignition on and note if test light is activated. If voltage exists, proceed to next step. If voltage did not exist, ensure no open or short exists in Dark Green wire to ECM. If wiring is okay, check ECM. For ECM checking procedure, see appropriate article in ENGINE PERFORMANCE section.
5. Install a fused jumper wire between Red wire and Black/White wire terminals of cooling fan relay (center position "B") at under-hood relay center. If cooling fan operates at low speed, check connections at relay. If connections are okay, replace cooling fan "B". If cooling fans did not operate, leave jumper wire installed and proceed to next step.
6. Disconnect cooling fan relay "C" from under-hood relay center. Ground Black/Pink wire terminal of relay "C" at under-hood relay center. If pusher fan operates at high speed, replace cooling fan relay "C". If pusher fan did not operate at high speed, proceed to next step.
7. Check for open in Black/White and Black/Pink wire circuits to pusher fan. Check connections at cooling fan. If wiring and terminals are okay, replace pusher fan.

Test C - No High Speed On Pusher Fan (4.5L)

1. With low speed operation okay, remove cooling fan relay "C" from under-hood relay center. Relay center is located in left front corner of engine compartment behind the headlight. Turn ignition on. Check for battery voltage at Red/White wire to ground. If no voltage exists, repair circuit.
2. Check for battery voltage between Red/White and Black wire terminals of relay connector. If voltage exists, check connections at cooling fan relay. If connections are okay, replace cooling fan relay. If voltage did not exist, check for open in Black wire (circuit 804) from relay to pusher fan.

Test D - No High Speed On Puller Fan (4.5L)

1. With low speed operation okay, remove cooling fan relay "D" from under-hood relay center. Relay center is located in left front corner of engine compartment behind the headlight. Turn ignition on. Check for battery voltage at Red/White and Red wires to ground.
2. If no voltage exists, repair open circuit. If voltage exists, enter ECM overrides and select ES08. Adjust diagnostic display to 01. Connect test light at Red/White wire and Light Green/Black wire terminals of cooling fan relay "D". If voltage exists, proceed to next step. If voltage did not exist, check for open in Light Green/Black wire (circuit 536).
3. Install a fused jumper wire between Red wire and Black/Pink wire terminals of cooling fan relay "D". If puller fan operates at high speed, check connections at cooling fan relay "D". If connections are okay, replace cooling fan relay "D". If puller fan did not operate, check for open in Black/Pink wire (circuit 533) for an open.

Scheme 6

1. Remove cooling fan relay "C" and "D" from under-hood relay center. Relay center is located in left front corner of engine compartment behind the headlight. Turn ignition on. Check for battery voltage from Red/White wire of cooling fan relays "C" and "D" and Red wire of cooling fan relay "D".
2. If voltage exists at all terminals, proceed to next step. If voltage did not exist, repair wiring circuit.
3. If voltage exists, check Light Green wire (circuit 536) for open or short to battery voltage. If wiring is okay, check ECM. For ECM checking procedure, see appropriate article in ENGINE PERFORMANCE section. If wiring is defective, repair as necessary.

WIRING DIAGRAMS

Note. Cooling fan wiring diagram for Trofeo not available at time of publication.

Cooling Fan Wiring Diagram (Eldorado). Scheme 7

Cooling Fan Wiring Diagram (Reatta & Toronado). Scheme 8

Note. Coolant Fan Relay C-Pin 1 is Blk/Wht on Riviera.

See also:
• SYSTEM CHECK
• TEST A - BOTH COOLING FANS INOPERATIVE
• TEST B - PUSHER FAN INOPERATIVE
• TEST C - NO HIGH SPEED ON PUSHER FAN
• TEST D - NO HIGH SPEED ON PULLER FAN