Question about 1999 Pontiac Firebird

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Cooling fans wont come on

I replaced all 3 relays & ect sensor didnt fix the problem. When ect is not plugged in fans come on what do i do next?

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  • Pontiac Master
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I think you may have a PCM problem, the fact the fans come on in "failure mode" when the ECT signal is lost indicates the circuits to the fans are ok. Technicians disconnect the ECT to verify fan operation as a quick test for checking the fan circuit and the fan motors. one last note, you do realize the fans don't come on until either the AC is on or the engine reaches approx 235 Degrees F. at idle that takes a long time.

Posted on Aug 21, 2008

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Posted on Jan 02, 2017

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Location of radiator fan relay 1992 ford tempo gl


The radiator cooling fan relay in ford Tempo gl has been integrated into the CCRM (Constant Control Relay Module) this is the black box fixed to the left strut tower with the big cable harness on it.

This relay box is commanded by the PCM (Powertrain Control Module) it´s linked to every sensor in the car. (It's located behind the fuse panel next to the steering column.

The PCM supervises various conditions, including the signal that the ECT (Engine Coolant Temperature) sensor sends and power up the Fan Relay into CCRM to activate the Cooling Fan.
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This should help.Thanks.Helpmech.

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Bought 2001 Lumina.. head gasket was leaking. fixed that n noticed cooling fan motors were not running. Replace all 3 relays n ect n fans started working. Drove it two days n it started runnin hot pulled...


I had a similar problem. Is your temperature gauge pegged to the right as very hot? Or reads always cold, even when hot. If it is a 3100 motor their is a coolant temperature gauge sending unit under the air breather intake that is right next to where you replace the thermostat.

Get a haynes repair manual at a parts dealer, Amazon, or your public library.
On the Chevrolet Lumina, Monte Carlo, & Impala FWD 1995 to 2005 it's under section 3-8 on page 3-6. It goes into great detail, and it's too complicated to explain here. If your sensor is bad, but the wires and fuses are good then the fans won't run.

Your second fan only runs when the air compressor is turning, If your ac compressor is not running then the sensor will not have the passenger fan run.
You have to see if the fan motors are good and then the wiring is good, and no fuses blown. You might blow fuses so have extra blue ones if I remember right. Recheck fuses after testing.

Feb 24, 2011 | 2001 Chevrolet Lumina

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95 toyota corolla 1.8 engine, cooling fan works but only when you disconnect the fan switch, or by pass the fan relay, it's not overheating, but it's causing the coolant to overflow the resivor. Replaced...


Check the engine main relay, the radiator fan relay no. 1, 30A CDS and FAN fuses, and the ECT (engine coolant temperature) sensor for proper function. For the ECT, there should be continuity when the engine is cold (200F).

Jan 12, 2011 | Toyota Corolla Cars & Trucks

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When I turn the car on the fans come on and stay on what could be the problem? Oh ya the temp gauge dosen't go pass 100.


either the radiator fan relay (electromagnetic switch) is shorted closed, applying power to fans constantly, or the engine coolant temp (ect) sensor is not or is unable to send proper signal to the computer cause the fans to default on ( this would also set the check engine light). I would check for codes first. Then check the relay to see if it is actuating properly when power is applied and removed. Next check the ECT for proper resistance. If the you get an over limit (OL) reading on your multimeter then the sensor is bad. Next I would check the wiring from the ECT sensor to the Powertrain Control Module for possible short to power or ground. If everthing checks out to this point it may be the PCM, though unlikely.

Dec 14, 2010 | 2001 Pontiac Grand Am SE

1 Answer

Where is the switch that cuts on the cooling fans on a 2000 grand am with a 3.4 engine


The computer turns on the fan. Based on sensors from the motor.
DTC P0480 - COOLING FAN CIRCUIT

Circuit Description

The cooling fan is controlled by PCM through the fan relay based on inputs from ECT sensor, IAT sensor, A/C selector switch, A/C refrigerant pressure switch and vehicle speed sensor. PCM controls cooling fan by grounding cooling fan control circuit which turns on cooling fan relay.

The fan relay will be commanded on when ECT reaches 223°F (106°C) or greater, A/C is requested or vehicle speed is less than 38 MPH. Cooling fan relay will also be commanded on regardless of vehicle speed when a DTC is set requesting cooling fan to be on, ECT is 304°F (151°C) or greater, or A/C refrigerant pressure is high. Cooling fan may also be commanded on when engine is not running, on certain conditions.

Conditions for setting DTC:

Battery voltage greater than 9.5 volts.

Cooling fan fault line detects a malfunction for 6 seconds.

1. Check cooling system. Ensure coolant level and belt tension are correct. Adjust/repair as necessary. After repairs, go to step 23). If no adjustment or repairs were required, go to next step.

2. Turn ignition on, with engine off. Using scan tool, check if cooling fan is operating with ECT at less than 209°F (98°C). If cooling fan is off, go to next step. If cooling fan is on, go to step 4).

3. Command cooling fan relay on. If cooling fan operates, go to step 23). If cooling fan does not operate, go to step 5).

4. Turn ignition off. Disconnect PCM harness connector. If cooling fan turns off, go to step 23). If cooling fan does not turn off, go to step 6).

5. Disconnect cooling fan relay harness connector. Using a test light connected to ground, probe battery feed circuits in relay harness connector. If test light illuminates on both terminals, go to step 7). If test light does not illuminate on both terminals, go to step icon_cool.gif.

6. Disconnect cooling fan relay harness connector. With test light connected to ground, probe battery feed circuit in relay harness connector. If test light illuminates, go to step 9). If test light does not illuminate, go to step 10).

7. Connect a jumper wire between cooling fan relay battery feed and cooling fan battery feed circuit. If cooling fan operates, go to step 11). If cooling fan does not operate, go to step 12).

8. Repair open in battery feed circuit. After repairs, go to step 23).

9. Repair short to voltage in cooling fan battery feed circuit. After repairs, go to step 23).

10. Connect test light battery voltage and probe cooling fan control circuit. If test light illuminates, go to step 13). If test light does not illuminate, go to step 21).

11. Connect test light to battery voltage and probe cooling fan control circuit. Using scan tool, command cooling fan on. If test light illuminates, go to step 14). If test light does not illuminate, go to step 15).

12. With jumper wire still connected, disconnect cooling fan harness connector. Using test light connected to ground, probe cooling fan battery feed circuit. If test light illuminates, go to step 16). If test light does not illuminate, go to step 17).

13. Repair short to ground in cooling fan control circuit. After repairs, go to step 23).

14. Check terminals to cooling fan relay. Repair as necessary. After repairs, go to step 23). If terminals are okay, go to step 21).

15. Check cooling fan control circuit for open or poor connection. Repair as necessary. After repairs, go to step 23). If circuit or connection is okay, go to step 22).

16. Connect test light to battery voltage and probe cooling fan ground circuit. If test light illuminates, go to step 1icon_cool.gif. If test light does not illuminate, go to step 19).

17. Repair open or poor connection in cooling fan ignition feed circuit. After repairs, go to step 23).

18. Check for poor connections at cooling fan harness connector. Repair as necessary. After repairs, go to step 23). If connections are okay, go to step 20).

19. Repair open or poor connection in cooling fan ground circuit. After repairs, go to step 23).

20. Replace cooling fan motor. After replacing cooling and motor, go step 23).

21. Replace cooling fan relay. After replacing relay, go to step 23).

22. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.

23. Turn ignition on, with engine off. Command cooling fan on. If cooling fan operates, system is okay. If cooling fan does not operate, repeat step 1).

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1 Answer

Can anyone tell me where to find the glowplug relay, it's a 7 prong relay, on a 2002 vw beetle 1.9 diesel no turbo ? allready been under the dash and checked all the relays, none of which are 7 prong,...


Above the Relay Panel is the Auxiliary Relay Panel. Has thirteen positions in it.
6 across the top, 7 across the bottom.

Across the bottom the Glow Plug Relay is the fourth one over from the left. It is Number 10.
(180)

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2005 chrysler 300c 5.7l v8 hemi.........over heating electric fans do not come on......however when fans are checked individually they work....the two fuses and the 3 relays check ok......made check with...


The fans are turned on by the PCM, if the PCM is not telling the fans to turn on, they won't even if everything tests fine.

2005 Chrysler 300 V8-5.7L VIN H

Coolant Temperature Sensor/Switch (For Computer): Service and Repair
ENGINE COOLANT TEMP SENSOR
REMOVAL
The Engine Coolant Temperature (ECT) sensor (3) on the 5.7L engine is located under the air conditioning compressor. It is installed into a water jacket at the front of the cylinder block.
WARNING: HOT, PRESSURIZED COOLANT CAN CAUSE INJURY BY SCALDING. COOLING SYSTEM MUST BE
PARTIALLY DRAINED BEFORE REMOVING THE COOLANT TEMPERATURE SENSOR.
1. Partially drain the cooling system.
2. Remove accessory drive belt.
3. Carefully unbolt air conditioning compressor from front of engine. Do not disconnect any A/C hoses from compressor. Temporarily support
compressor to gain access to ECT sensor (3).
4. Disconnect electrical connector (2) from sensor (3).
5. Remove sensor (3) from cylinder block.
INSTALLATION
1. Apply thread sealant to sensor threads.
2. Install ECT sensor (3) to engine.
3. Tighten sensor to 11 Nm (97.3 inch lbs.) torque.
4. Connect electrical connector (2) to ECT sensor (3).
5. Fill the cooling system.

Sep 10, 2009 | 2005 Chrysler 300

2 Answers

Cooling fans dont engage! 1998 oldsmobile silhouette!


Your Problem Can VERY WELL BE with the Temp Sensor, As It Is the First in This Electrucal Circut . it Waits for 210-230 Degree Engine temp and Gives that Sygnal to the ECM then ECM Grounds out the Cooling FAN RELAY To Turn ON the FANS and the Temp Sensor is Usualy THE #1 Culpret Closley in front of the RELAY.
There are 2 Sensors On this Vehicle The One You Replaced and One Located At Trans Side of
Engine Closer to Front of Vehicle At the Head ,Thereis a 2 wire Plug On it and This Sensor Goes to the ECT witch CONTROLS COOLING FAN RELAY. Hope this Helps and if you Need A Diagram For this It Must be Emailed as FixYa Does NOT Support Large Picture Files. My Email Add. Is MY
Screen Name Here on FixYa @aol.com

Jun 15, 2009 | 1998 Oldsmobile Silhouette

1 Answer

I want to know where the Coolant Temp sensor is on a 04 2.4 PT


the engine coolant temp sensor is in the assembly that the pressure cap (radiator cap) goes on. it's under the part that the cap goes on, closer to the engine block. you can see the wires and the plug going to it. here's the remove and replace step by step:
1. disconnect battery negative terminal (they always tell you to do that when you work on electrical parts)
2.partially drain cooling system below level of ect sensor
3.disconnect ect sensor
4.remove ect sensor
and to reinstall
1.install ect sensor torque to 168 in-lbs
2.connect sensor electrical connector
3.connect battery negative terminal
4.refill system with coolant
hope that helps

Jun 03, 2009 | 2004 Chrysler PT Cruiser

3 Answers

Van chevrolet venture 2000


Fifteen minutes! you have bigger problems than only the fans the fans are controlled by a thermo switch that is heated by the coolant, If you have no coolant the sensor cannot activate But fifteen minutes seems like you may have a headgasket problem and steam cannot heat the coolant sensor.OperationNotesThe electric cooling fan operates when the engine cooling temperature exceeds a certain value. The cooling fan on this engine is controlled by the Powertrain Control Module (PCM) . The PCM turns the cooling fan ON by grounding the coil of the cooling fan relays 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 Maxifuses(R). The cooling fan relays are energized when current flows from the fuses in the Underhood Accessory Wiring Junction Block, and through the relay coils to ground through the PCM. The Coolant Fan 1 Relay Control Circuit is grounded for low speed fans operation. During low speed fans operation, both fans run at a slow speed. The Coolant Fan 1 Relay 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. Perform the A Powertrain On Board Diagnostic (OBD) System Check prior to diagnosing the engine cooling fans.

For more information regarding the Charging System, refer to Charging System Description , and Charging System Circuit Description in Starting and Charging.

If a problem that involves the low speed cooling fan relay control circuit exists, DTC P0480 Cooling Fan Relay 1 Control Circuit should set. If the problem affects the high speed cooling fan relay control circuit, DTC P0481 Cooling Fan Relay 2 Control Circuit should set. A problem with the ECT sensor should set DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage, DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage, DTC P1114 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage, DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage. Any of these DTCs will affect cooling fan operation and should be diagnosed before using the Electric Cooling Fan Diagnosis.

For more information regarding the Cooling System refer to Engine Cooling Fan Description - Electric, and Cooling System Description in Cooling System.


Here is the electrical schematic and how it all is suppose to work,
If you need any further help please contact me Thank you,Randy If you find this information helpful please give me a good rating

www.aceautomotive1.com

Aug 16, 2008 | 2000 Chevrolet Venture

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