radiator fan not comming on - Pontiac G6 Forum
 
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post #1 of 8 (permalink) Old 06-10-2012, 05:03 PM Thread Starter
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radiator fan not comming on

ive noticed lately that sometimes when i cut my car off the fan would run for about a minute after the car is off and i found this kind of strange because my temperatures were normal. yesterday while driving the car temp went extremely high and i noticed that the compressor fan was not plugged in when i looked at it and none of the fans were spinning. so i thought that this wouldhave fixed my problem. went to start the car and i let it run until it reached normal temp again and i was waiting to see if the fans were going to come on wen it reached that temp the compressor fan was working. but the radiator fan would not come on. so i tested the radiator fan to see if it was working by jumping it directly to the battery and what do you know it works. so i drove it home like that and now i am trying to figure out what may be causing the fan not to come on at a certain temperature. any ideas you guys? i am thinking a relay or a fan switch idk am lost.
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post #2 of 8 (permalink) Old 06-11-2012, 07:11 AM
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If the fan physically works with direct power, then you need to start looking at fuses and relays. If you replace those and it still doesn't work, then you'd need to look towards the computers. I'm just not sure if its the pcm or bcm that controls the fan on this car.

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post #3 of 8 (permalink) Old 06-11-2012, 12:08 PM
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Most common problem with the fans is with the fan connector melting from an increase in resistance. If yours looks good, than troubleshooting is needed. Here's how they are supposed to work:

https://www.g6ownersclub.com/forum/at...1&d=1339438024

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a Series/Parallel configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.

During low speed operation, the ECM supplies the ground path for the low speed fan relay, which is Cool/Fan 1 Relay 28 through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the Cool/Fan 1 Fuse 17 through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the Series/Parallel relay, which is the cool SER/PAR relay 29, and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation, the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. The ECM supplies a ground path for the high speed fan relay , which is Cool/Fan 2 Relay 30, and the Series/Parallel relay through the high speed cooling fan relay control circuit . This energizes the Series/Parallel relay, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high fan speed relay coil is energized, the relay contacts close to provide battery positive voltage from the Cool/Fan 2 Fuse 18 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.

When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 10 mph. This is to prevent a fan from cycling ON and OFF excessively at idle.

When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position, or the vehicle speed exceeds approximately 16 km/h (10 mph). This is to prevent a fan from cycling ON and OFF excessively at idle.



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post #4 of 8 (permalink) Old 06-11-2012, 12:12 PM
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Here's the diagnostic & schematic:


Service Information
2008 Pontiac G6 | G6 (VIN Z) Service Manual | Document ID: 1937984
--------------------------------------------------------------------------------

Cooling Fan Inoperative
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description
The engine control module (ECM) commands the fans ON in high speed or low speed. In low speed, the fans are configured in series. In high speed, the fans are configured in parallel.

In low speed operation, the ECM applies ground to the coil side of the low speed fan relay, which is Cool/Fan 1 Relay 28. Voltage is applied directly to the left cooling fan through the switch side of the low speed fan relay. The right fan is connected in series to the left fan through the de-energized series/parallel relay, which is the Cool SER/PAR Relay 29, so that both operate at low speed.

In high speed operation, the ECM applies a ground to the coil side of the low speed fan relay, the series/parallel relay, and the high speed fan relay, which is the Cool/Fan 2 Relay 30. Voltage is applied directly to the right cooling fan through the switch side of the high speed fan relay. The left cooling fan obtains voltage through the low speed fan relay and ground through the series/parallel relay.

When the ECM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volt. When the ECM is commanding a fan relay OFF, the voltage of the control circuit should be high, near battery voltage. If the ECM detects that the actual voltage of the relay control circuit is different than the expected voltage, DTC P0480 or P0481 will set and the affected ECM driver will be disabled.

Reference Information
Schematic Reference
Engine Cooling Schematics

Connector End View Reference
Component Connector End Views

Description and Operation
Cooling System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Wiring Repairs


Circuit/System Verification
If DTCs P0480 or P0481 are set, then perform those diagnostics first.
Ignition ON, command each relay ON and OFF with a scan tool. Feel or listen to verify that each relay turns ON and OFF with each command.
Circuit/System Testing
Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

Ignition OFF, disconnect the series/parallel relay, which is Cool SER/PAR Relay 29.
Ignition ON, activate the cooling fan relay 1 with a scan tool. The fan should be OFF.
⇒ If the fan is activated, test the left fan ground circuit for a short to ground.

Ignition OFF, disconnect the remaining relays.
Install a 30A fused jumper between the normally-open switch contact terminals 30 and 87 at the series/parallel relay connector in order to complete the fan ground circuit. Leave this jumper in place for the remainder of this procedure.
One at a time, connect a 30A fused jumper between the positive terminal at the battery and the fan voltage supply circuit terminal 87 at the low speed fan relay, which is Cool/Fan 1 Relay 28, and the high speed fan relay, which is Cool/Fan 2 Relay 30, connections and verify fan activation.
⇒ If the appropriate fan does not activate, test the fan voltage supply circuit for a short to ground or open/high resistance. If the circuit tests normal, test the fan ground circuit for an open/high resistance. If the circuits test normal, replace the fan.

Ignition ON, connect a 30A fused jumper between the relay switch voltage supply circuit terminal 30 and the fan voltage supply circuit terminal 87 at the low speed fan relay and the high speed fan relay connections and verify fan activation.
⇒ If the fan does not activate, test the relay switch voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.

If the circuits and fans test normal, replace the relay.
Repair Instructions
Cooling Fan and Shroud Replacement

Control Module References for ECM replacement, setup, and programming.

Repair Verification
Ignition ON, command the relay ON and OFF with a scan tool. Observe to verify that the fan turns ON and OFF with each command.
2012 General Motors Corporation. All rights reserved.

https://www.g6ownersclub.com/forum/at...1&d=1339438311



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post #5 of 8 (permalink) Old 06-12-2012, 10:26 PM Thread Starter
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thanks guys for the replies. turns out that the coolant was really low i didnt notice until the car was off and the reserviour was dry. and it turns out that i did have a bad relay fan 1. now this is my next question is the two fans supposed to be on at a low speed when the car is idling? if so mines doesnt. fan 1 kicks in when the car is alittle over 225 and shuts off when it reaches under and continues in this fashion. also a really strange thing that ive noticed is that sometimes when i run the ac for a long time and turn the car off. the temperature on the gauge climes well over 225 slowly and the fans cut on until it goes back down.this is the first time ive ever seen a car run hot when its turned off. during operation it does not run hot, any ideas with that ?
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post #6 of 8 (permalink) Old 06-12-2012, 11:25 PM
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Quote:
Originally Posted by G6freak View Post
thanks guys for the replies. turns out that the coolant was really low i didnt notice until the car was off and the reserviour was dry. and it turns out that i did have a bad relay fan 1.
If the coolant level was low then you have a leak somewhere. Could be internal.

Quote:
now this is my next question is the two fans supposed to be on at a low speed when the car is idling? if so mines doesnt. fan 1 kicks in when the car is alittle over 225 and shuts off when it reaches under and continues in this fashion.
Depends on engine temp & whether the a/c is running.

Quote:
also a really strange thing that ive noticed is that sometimes when i run the ac for a long time and turn the car off. the temperature on the gauge climes well over 225 slowly and the fans cut on until it goes back down.this is the first time ive ever seen a car run hot when its turned off. during operation it does not run hot, any ideas with that ?
That sounds normal. Sounds like you having hot weather now.



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post #7 of 8 (permalink) Old 06-13-2012, 03:44 PM Thread Starter
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the coolant was low because the idiot that put the engine in did not put the right amount of coolant but there are no leaks. and yea i am having hot weather right about now because i live in the bahamas. . but everything is working fine now thanks alot guys.
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post #8 of 8 (permalink) Old 06-05-2018, 10:54 AM
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llalfafan woe

what and where is the ECM and how do I direct wire
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