Question about 2000 Oldsmobile Alero

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Cooling fans will not run

2002 olds. alero engine temp. does the pcm control the cooling fans?

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  • Anonymous Mar 18, 2014

    engine coolant temp gauge inoperative

  • Anonymous Mar 28, 2014

    pcm wiring diagram

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Yes, but it gets it's signsl from the temp sensor for the emissions system, not the one from the temp guage sensor. It could also be a fuse or relay.

Posted on Dec 27, 2008

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I have a 2002 Lincoln town car and I just put a brand new fan in and its not coming on my car runs hot when I have it in park with the ac on


Did you check the fan relays ? There are two, cooling low relay an cooling fan high relay . The relays are turned on by the vehicles PCM - engine computer , when an input from the coolant temp. sensor indicates a certain temperature ! When you turn on your A/C the cooling fan should turn on an stay on .
Relay Box
Left center of engine compartment
Cooling Fan High Relay
In relay box
Cooling Fan Low Relay
In relay box
Do you know how to test a computer controlled relay ? Go to you tube an search relay testing . Does the temp. gauge work correctly ? I know you probably don't have a factory scan tool , but this is the where I would start , checking temp. sensor input to the PCM . An with a factory scan tool I can do bidirectional testing , see if I could turn the fans on will scan tool .

Mar 17, 2016 | Lincoln Cars & Trucks

1 Answer

The location of a 2002 chevy cavalier cooling fan sensor


The cooling fan is controlled by the PCM - powertrain control module through a relay ! There is no cooling fan sensor , there is a coolant temperature sensor ! This coolant temperature sensor is an input to the engine computer , if there were a problem wit the sensor the check engine light would be on .
Cooling Fan Control
The engine cooling fan system consists of one cooling fan and one relay. The relay is powered by the battery positive voltage circuit and controlled by a switched ground from the powertrain control module (PCM).
During operation, the PCM supplies the ground path for the cooling fan relay through the cooling fan relay control circuit. This energizes the cooling fan relay coil, closes the relay contacts, and supplies battery positive voltage from the cooling fan fuse through the cooling fan motor supply voltage circuit to the cooling fan. The cooling fan motor is grounded through its own ground circuit.
The PCM commands the fan on under the following conditions:
?€¢
Engine coolant temperature exceeds approximately 106?°C (223?°F).


?€¢
A/C refrigerant pressure exceeds 1310 kPa (190 psi).


?€¢
A/C is requested and vehicle speed is below 100 km/h (62 mph) with A/C pressure above 1413 kPa (205 psi).


?€¢
Vehicle speed is less than 8 km/h (5 mph) for more than 750 seconds. The fan will turn off when vehicle speed is greater than 8 km/h (5 mph) for more than 20 seconds.

Jun 12, 2015 | 2002 Chevrolet Cavalier

1 Answer

I have a 2002 Chevy Malibu 3.1 and I'm looking for where the engine cooling fan sensors location. Can anybody help me?


Unlike many older vehicles, there isn't a separate coolant switch for the radiator fans. The engine coolant sensor that provides coolant temp to the PCM for control of the fuel/spark/timing is the same sensor used by the PCM to control activation of the radiator fan(s).
The PCM activates the fans by activating relay 12 in the underhood fuse block for low speed operation and relays 12, 14, and 15 for high speed operation. If the engine is running normally other than the fan, the problem is not going to be the coolant sensor. But, if you need to see for yourself, the coolant sensor is on the drivers side of the engine, below and just forward of the throttle body. See the picture for clarity.
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Dec 06, 2013 | Cars & Trucks

1 Answer

1987 olds cutlass ciera 3.8 cooling fan runs when engine is cold; changed cooling fan switch and temp sensor, fan relay times out OK.


the coolant fan does not only cool down engine temp. it also run if pcm detect a problem .or ac request. see pcm data to find out code or data out of range

Aug 21, 2013 | 1987 Oldsmobile Ciera

1 Answer

Cooling fans run continuosly on 2001 alero


When the temp sensor fails, the computer will turn on the fan relay as a precaution to overheating.
Once you find the problem with the sensor you may also fix the fan problem.
If the check engine light is on you should also check the computer for trouble codes.

Feb 21, 2013 | 2000 Oldsmobile Alero

2 Answers

I have a 1999 Alero 3.4 V6 the cooling fans won't run. I checked the fans they both work if I unplug the harness for the temp sensor,the relays and fuses are fine,I replaced the coolant temp sensor and...


CHECK MODE RELAY IF BOTH RELAYS GOOD YOU CAN CHECK RELAY BY REMOVING IT FROM FUSE BOX HOOK RELAY TERMINAL 85 TO BATTERY POSITIVE AND GROUND TERMINAL 86 IF CLICKS RELAY GOOD. IF RELAY GETTING POWER GOOD AND THE 30 AMP COOLING FAN FUSE OKAY.EITHER THERE IS A SHORT IN COOLING FAN WIRING OR THE PCM HAS FAILED.THE PCM HAS LOST OR COMMAND RUN CIRCUIT IN PCM SHORTED OUT DUE TO PCM FAILURE.LET DEALERSHIP OR GARAGE USE DIAGNOSTIC EQUIPMENT TO ACTIVATE THE PCM SEE IF IT HAS FAILED.DONT SPEND MONEY ON NEW PCM COULD BE SHORT IN THE WIRING CIRCUIT

Sep 06, 2011 | 1999 Oldsmobile Alero

1 Answer

My Alero heats up when I stop at a traffic light. Everything checks out ok. No leaks, new temp sensor, etc. Any ideas?


CHECK COOLING FAN SEE IF ITS RUNNING.IT NOT CHECK COOLANT FAN FUSE AND RELAY.IF ALL IS GOOD HOTWIRE COOLANT FAN SEE IF IT RUNS.IF NO REPLACE FAN.IF YES CHECK FAN WIRING AND CODE SCAN VECHICLE FOR PCM FAULT CODE.

Feb 26, 2011 | 1999 Oldsmobile Alero

1 Answer

1999 Olds Alero 4 cyl running hotter than normal. One mechanic says it's Heat sensor that opens and closes. The other mechanic who ran car says it was thermostat that turns on dual fans. Ok well one was...


REPLACE THERMOSTAT.ITS STICKING CLOSE TO KEEP COOLANT FROM CIRCULATING THROUGH ENGINE AND RADIATOR. THE FANS SHOULD COME ON WHEN VECHICLE SETTING AT A LONG IDLE.THE COOLANT TEMPERATURE SENSOR GET TO CERTAIN TEMPERATURE WHICH WILL COMPLETE CIRCUIT PCM SEND POWER TO COOLANT SENSOR THEN TO COOLANT FANS RELAYS AND FANS.IF VECHICLE OVER HEATING WHILE MOVING THERMOSTAT FAULTY.IF YOU TURN AC AND COOLANT FANS DONT RUN CHECK COOLANT FANS FUSE AND RELAY.IF COOLING FANS DONT TURN ON WITH AIR CONDITIONER ON EITHER COOLANT TEMPERATURE SENSOR FAULTY OR PCM FAULTY.IF ALL LOOKS GOOD.IF ENGINE OIL LOOKS LIKE MILK SHAKE.YOU HAVE BLOWN HEAD GASKET.

Nov 11, 2010 | 1999 Oldsmobile Alero

1 Answer

Eng. code P1484


P1484 - Cooling Fan System Performance

06-06-2005, 10:51 PMHere's what the GM Manual says about this code:

The cooling fan relay sends a pulse width modulation (PWM) signal of 12-14 volts to the cooling fan clutch through the cooling fan clutch supply voltage circuit. The powertrain control module (PCM) uses this PWM signal in order to control the speed of the cooling fan clutch. The signal controls the position of the oil control valve inside the cooling fan clutch. If the cooling fan RPM is different than the PCM is expecting, DTC P1484 will set. The actual cooling fan RPM vs the desired cooling fan RPM is not always exactly the same. There can be up to an 800-RPM difference.

The engine is running.
The system voltage is greater than 8.5 volts.
The intake air temperature (IAT) is greater than -7°C (19°F).
DTCs P1481 and P1482 are not set.
The engine speed is less than 3200 RPM.
The engine speed is not changing more than 250 RPM for 5 seconds.
Fan command is greater than 0%.


The maximum allowable error of 1000 RPM in the cooling fan speed occurs for 100 seconds.
The PCM detects that the cooling fan clutch is locked up.


The Reduced Engine Power indicator illuminates only if the PCM detects that the cooling fan clutch is locked up.
The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
The PCM will store the conditions as Freeze Frame/Failure Records data.
The PCM commands the cooling fan clutch to 100%.

Important
Follow this procedure in order to clear DTC P1484 after completing a repair.



Use the Clear DTC Information function on the scan tool.
Perform an ignition key cycle.
The PCM turns OFF the MIL after the third consecutive trip that the diagnostic test has run and passed.

The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

An inline connector could cause an intermittent DTC. Ensure to test for poor connections and pin retention at all inline connectors. Refer to system schematics for connector and locations.
If the condition is not present, refer to Testing for Intermittent and Poor Connections in Wiring Systems.

Disconnect the harness connector of the cooling fan clutch from the shroud. Inspect the exposed wires between the harness connector and the tubing.
If DTCs P1484 and P0113 are set, and the weather conditions are cold, the cooling fan code may be false. Clear DTC P1484, and after an IAT sensor check, allow the DTC to reset .

I'd say that 'fan clutch is faulty' is your problem, based on the information you gave. Thank you for using Fixya and good luck

Jul 10, 2010 | 2002 Chevrolet TrailBlazer

1 Answer

Temp gauge often reads too hot, engine normal.


It sounds like your cooling fans are not comming on by themselves, but when you turn on the ac it forces them to turn on. Make sure relay is good, then replace coolant temp sensor, this may have failed no telling pcm to turn on cooling fans. Thanks

Jun 08, 2009 | 2002 GMC Safari

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