Question about 2000 Oldsmobile Alero

1 Answer

Cooling fans will not run

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

Posted by on

  • Anonymous Mar 18, 2014

    engine coolant temp gauge inoperative

  • Anonymous Mar 28, 2014

    pcm wiring diagram

×

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Master
  • 405 Answers

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

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

I have a 2005 uplander, the fans operate periodically when they should not. Have changed one senser.


How do you know when the fans should or should not work ? The PCM - engine control module tells the fans when to work . A coolant temp. sensor inputs coolant temp info to the PCM . Fans can come on when the vehicle isn't running , depending on temp. The cooling fans are turned on by the PCM using three relays . You best bet would be to take your vehicle to a qualified repair shop . Relay Driven Dual Cooling Fan Diagnostics

Dec 19, 2016 | 2005 Chevrolet Uplander

1 Answer

Where is the cooling fan switch located on my 2005 malibu 3.5liter v6


Cooling fan switch ? The cooling fans (2) on that motor are controlled by three relays . A coolant temp. sensor gives temp info to the PCM - engine computer .
During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan S/P relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan S/P relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
The PCM commands Low Speed Fans on under the following conditions:
• Engine coolant temperature exceeds approximately 106°C (223°F).
• When A/C is requested and the ambient temperature is more than 50°C (122°F).
• A/C refrigerant pressure exceeds 1 310 kPa (190 psi).
• After the vehicle is shut off if the engine coolant temperature at key-off is more than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands High Speed Fans on under the following conditions:
• Engine coolant temperature reaches 110°C (230°F).
• A/C refrigerant pressure exceeds 1 655 kPa (240 psi).
• When certain DTCs set .
Watch this video ,it shows how it works !
Relay Driven Dual Cooling Fan Diagnostics

Nov 27, 2016 | 2005 Chevrolet Malibu

1 Answer

Need a wiring diagram of the 2 wires from the temp sending unit that controls the temp gauge and cooling fans on a 99 grand am gt. Need to see where they go They disappear behind the engine


The PCM regulates voltage to the coolant fan relays, which operate the fans. Refer to Engine Controls.

Engine Cooling Fan Description - Electric
The electric cooling fans are used to lower the temperature of the engine coolant flowing through the radiator. They are also used to cool the refrigerant (R-134a) flowing through the A/C condenser.
Operation
The electric cooling fan operates when the engine cooling temperature exceeds a certain value. The cooling fan on this engine is controlled by the PCM. The cooling fan has one speed. The PCM turns the cooling fan ON by grounding the coil of the cooling fan relay when certain conditions are met. When the A/C is requested, the cooling fan will also be turned ON.
Power for the cooling fan motors are supplied through Cool Fan #1 and Cool Fan #2 relays. The cooling fan relays are energized when current flows from the fuses in the Cell 23: Cooling Fan Controls , and through the relay coils to ground through the PCM. The Low Speed fans control circuit is grounded for low speed fans operation. During low speed fans operation, both fans run at a slow speed. The High Speed fans control circuit is grounded for high speed operation. During high speed fans operation, both fans run at high speed.
Important: When certain Diagnostic Trouble Codes (DTCs) are present, the PCM may command the cooling fans to run all the time. It is important to perform Powertrain On Board Diagnostic (OBD) System Check prior to diagnosing the engine cooling fans.
If a problem that involves the low speed cooling fan relay control circuit exists, DTC P0480 should set. If the problem affects the high speed cooling fan relay control circuit, DTC P0481 should set. A problem with the ECT sensor should set DTC P0117, P0118, P1114, or P1115. Any of these DTCs will affect cooling fan operation and should be diagnosed before using the Cooling Fan Diagnosis tables. The Cooling Fan Diagnosis tables should be used to diagnose the PCM controlled cooling fans only, if a DTC has not set.

The engine coolant temperature (ECT) sensor (3) is a thermistor, a resistor which changes value based on temperature, mounted in the engine coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40°C) (-40°F), while high temperature causes low resistance (70 ohms at 130°C) (266°F).
The PCM supplies a 5 volt signal to the ECT sensor through a resistor in the PCM and monitors the terminal voltage. Since this forms a series circuit to ground through the ECT sensor, high sensor resistance (low temperature) will result in high PCM terminal voltage. When the resistance of the ECT sensor is low (high temperature), the terminal voltage will be drawn lower. This terminal voltage indicates engine coolant temperature to the PCM.
A hard fault in the ECT sensor circuit should set either a DTC P0117 or P0118. Remember, these DTCs indicate a malfunction in the engine coolant temperature circuit, so proper use of the DTC table may lead to either repairing a wiring problem or replacing the sensor, to properly repair a problem.

The engine coolant sensor is an input to the PCM , Two wire's both go to the PCM .An the PCM turns on the cooling fans !

DTC P0480 Cooling Fan Relay 1 Control Circuit
DTC P0481Cooling Fan Relay 2 Control Circuit
The Body Control Module (BCM) request the cooling fans. The BCM sends a Class 2 message to the PCM in order to enable the fans based on various inputs. Thebattery voltage travels to all three cooling fan relay coils. The PCM enables cooling fan relay #1 by providing the ground path. The PCM enables cooling fan relays #2 and mode control together by providing a ground path. The left and right cooling fans are connected in series. This will enable both fans on low speed when the fan #1 relay is energized. When all three fan relays are energized, both fans will operate at high speed. The high speed is possible because the fan relays are wired in a parallel circuit. When the PCM detects that certain DTCs are set, the PCM will enable the cooling fans.
The PCM will enable the engine cooling fans when certain Diagnostic Trouble Codes are set.

Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.
1
Did you perform the Instrument Cluster System Check?
--
Go to Step 2
Go to Instrument Cluster System Check
2
Turn the ignition switch to the ON position.
With the scan tool select Instrument Panel Cluster, Special Functions, Instrument Panel Cluster (IPC) gauges.
Perform the Coolant Gauge Sweep Test.
Does the coolant temperature gauge complete a full sweep when commanded?
--
Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls
Go to Step 3
3
Replace the instrument cluster. Refer to Instrument Cluster Replacement .
Did you complete the repair?
--
Go to Instrument Cluster System Check
--

Your best bet would be to take your vehicle to a qualified repair shop that knows how the system works . An has the tools to diagnose the problem .

Nov 13, 2016 | 1999 Pontiac Grand Am GT

1 Answer

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

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.
78927ff5-cdb8-4efe-be2a-3933ba27de5a.jpg

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

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

Not finding what you are looking for?
2000 Oldsmobile Alero Logo

438 people viewed this question

Ask a Question

Usually answered in minutes!

Top Oldsmobile Experts

yadayada
yadayada

Level 3 Expert

68032 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22011 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

6817 Answers

Are you an Oldsmobile Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...