Vehicle Is Overheating

The Problem noticed on 1999 Pontiac Sunbird.The vehicle overheats and Cooling fan not turning ON.
But when the Obd code scanner is connected to DTC port the fan comes ON and when OBD code scanner is disconnected the Fan Turns off and will not turn ON.

WHY FAN TURNS ON WHEN ERROR CODE SCANNER IS CONNECTED?


The cooling  fan operating system is pretty simple. You scanning it, and the fan coming on tells you the ECM is turning on the relay when requested. So we know that the Relay, and ECM command CKT to the relay {Dk Green/White wire} is engaging the relay.That is why Fan is accepting the voltage from relay and Turning ON.

SEE THE FAN WIRING DIAGRAM AND OTHER PARTS WIRING THAT MAKE THE FAN OPERATE


SO WHAT DO YOU THINK THE PROBLEM IS?

Coolant temperature sensor and its signal to ECM needs to be inspected.
It seems that coolant temperature signal voltage is high.

You have to verify the coolant Temp Sensor is sending proper info to the ECM. If the DATA stream on the scanner reads 226 to 230 degrees, and the fan does not come on, then you know the sensor is operational, and the ECM is not processing the info correctly.
This is common issue noticed many a times at our garage.The Fan gets inoperative due to faulty ECM.

SO WHAT IS FAULTY COOLANT TEMPERATURE SENSOR OR ECM?

To confirm that testing is required.I have already provided you the wiring diagram.That will help you the most to confirm what is faulty as per voltage test.


In the the diagram I attached above, you see the yellow and black wires to the Temp Sender. You need to verify that you have a good ground on the Black wire, and 5 Volts on the yellow. If you do, jumper the pins. If the fan comes on, replace the sensor. If not, chances are the ECM is bad.

WHAT IS MOST POSSIBLE OUT OF ECM OR SENSOR?

As per you description i assume its faulty ECM.

The fact that the Fan came on with the code checker installed, this puts the system in "Field Service Mode" and will have the ECM turn on relays, so we can assume that the ECM has an internal issue if the Sensor and it's CKT's are good.

This will help.

Thanks.

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How to replace Heater core on 2005 Dodge truck?

If you need dis-assembly or replacement instructions for any other auto/car part, or you want to ask question related to your car/truck jeep problem then please leave the comment with your details, so I can provide you the required instructions and solutions.

Removal & Installation

1. Disconnect the negative battery cable.
   
   CAUTION

   After disconnecting the negative battery cable, wait 2 minutes for the driver-s/passenger-s air bag system capacitor to discharge before attempting to do any work around the steering column or instrument
2. On diesel models, remove the passenger side battery and battery tray.
3. Remove the instrument panel by performing the following procedures:
   1. Remove the air bag control module (ACM) and bracket from the floor panel tunnel.
   2. Remove the trim from both cowl side inner panels.
   3. Remove the steering column-to-instrument panel opening cover.
   4. Remove the 2 hood latch release handle-to-instrument panel lower reinforcement screws and lower the handle to the floor.
   5. Disconnect the driver-s side air bag module wiring harness connector from the lower instrument panel reinforcement.
   6. Place the wheels in the straight-ahead position and lock the steering wheel. Remove the steering column without disassembling it.
   7. From under the driver-s side of the instrument, disconnect or remove the following items:
      
      
      Parking brake release handle linkage rod from the parking brake mechanism located on the left cowl side inner panel.
      

      Instrument panel wiring harness connector from the parking brake switch located on the parking brake mechanism.
      

      Three wiring harness connectors (body wiring harness, headlight, dash) from the 3 junction block connector receptacles located closest to the dash panel.
      

      Head light/dash-to-instrument panel bulkhead wiring harness connector screw and disconnect the connector.
      

      Instrument panel-to-door wiring harness connector located directly below the bulkhead wiring harness connector.
      

      Infinity sound system wiring harness connector (if equipped), located at the outboard side of the instrument panel bulkhead connector.
      

      Stop light switch electrical connector.
      

      Vacuum harness connector located near the left side of the heater/air conditioning housing.
      
   8. Under the passenger-s side of the instrument panel, disconnect the radio antenna coaxial cable connector.
   9. Loosen both sides of the instrument panel cowl side roll-down bracket screws about ¹ / ₂ inch (13mm).
   10. Remove the 5 upper instrument panel-to-upper dash panel screws; remove the center screw last.
   11. Roll down the instrument panel and install a temporary hook in the center hole on top of the panel. Attach the other end to the center hole in the top of the dash panel. The opening should be approximately 18 inches (46cm).
   12. Disconnect the instrument panel-to-heater/air conditioning housing assembly wiring harness connectors.
   13. Using an assistant, remove the instrument panel from the vehicle.
4. If equipped with air conditioning, perform the following procedure:
   1. Discharge and recover the air conditioning system refrigerant.
   2. Disconnect the refrigerant lines from the evaporator. Plug the openings to prevent contamination.
   3. Disconnect the refrigerant lines from the accumulator. Plug the openings to prevent contamination.
   4. Remove the accumulator.
5. Drain the cooling system into a clean container for reuse.
6. Disconnect the heater hoses from the heater core tubes.
7. Remove the PCM from the dash panel and move it aside. Do not disconnect the PCM harness connector.
8. In the engine compartment, remove the heater/air conditioning housing assembly-to-chassis nuts.
9. In the passenger-s compartment, remove the heater/air conditioning housing-to-dash panel nuts.
10. Pull the heater/air conditioning housing assembly rearward far enough to clear the studs and air conditioning drain tube holes.
11. Remove the heater/air conditioning housing assembly from the vehicle.
12. Remove the upper-to-lower heater/air conditioning housing screws and remove the upper housing.
13. Remove the heater core from the lower housing.
    
    
    

    

    Fig. Exploded view of refrigerant line
    Exploded view of refrigerant line
    
    
    

    

    Fig. View of the instrument panel
    View of the instrument panel
    
    
    

    

    Fig. View of the heater/air conditioning housing assembly
    View of the heater/air conditioning housing assembly
    
    
    

    

    Fig. View of the heater core
    View of the heater core

To install:

1. Install the heater core in the lower housing.
2. Install the upper housing and the upper-to-lower heater/air conditioning housing screws.
3. Install the heater/air conditioning housing assembly to the vehicle.
4. Push the heater/air conditioning housing assembly forward far enough to engage the studs and air conditioning drain tube holes.
5. In the passenger-s compartment, install the heater/air conditioning housing-to-dash panel nuts.
6. In the engine compartment, install the heater/air conditioning housing assembly-to-chassis nuts.
7. Install the PCM to the dash panel.
8. Connect the heater hoses to the heater core tubes.
9. Refill the cooling system.
10. If equipped with air conditioning, perform the following procedure:
    1. Install the accumulator.
    2. Connect the refrigerant lines to the accumulator.
    3. Connect the refrigerant lines from the evaporator.
    4. Evacuate and charge the air conditioning system refrigerant.
11. Install the instrument panel by performing the following procedures:
    1. Using an assistant, install the instrument panel to the vehicle.
    2. Connect the instrument panel-to-heater/air conditioning housing assembly wiring harness connectors.
    3. Roll-up the instrument panel and install a temporary hook in the center hole on top of the panel and the top of the dash panel. The opening should be approximately 18 inches (46cm).
    4. Install the 5 upper instrument panel-to-upper dash panel screws; install the center screw first.
    5. Install both sides of the instrument panel cowl side roll-down bracket screws to about ¹ / ₂ inch (13mm).
    6. Under the passenger-s side of the instrument panel, connect the radio antenna coaxial cable connector.
    7. Under the driver-s side of the instrument, connect or install the following items:
       
       
       Vacuum harness connector located near the left side of the heater/air conditioning housing.
       

       Stoplight switch electrical connector.
       

       Infinity sound system wiring harness connector (if equipped), located at the outboard side of the instrument panel bulkhead connector.
       

       Infinity sound system wiring harness connector (if equipped), located at the outboard side of the instrument panel bulkhead connector.
       

       Instrument panel-to-door wiring harness connector located directly below the bulkhead wiring harness connector.
       

       Headlight/dash-to-instrument panel bulkhead wiring harness connector and install the screw.
       

       Three wiring harness connectors (body wiring harness, headlight, dash) from the 3 junction block connector receptacles located closest to the dash panel.
       

       Instrument panel wiring harness connector to the parking brake switch located on the parking brake mechanism.
       

       Parking brake release handle linkage rod to the parking brake mechanism located on the left cowl side inner panel.
       
    8. Install the steering column.
    9. Connect the driver-s side air bag module wiring harness connector to the lower instrument panel reinforcement.
    10. Install the 2 hood latch release handle and the handle-to-instrument panel lower reinforcement screws.
    11. Install the steering column-to-instrument panel opening cover.
    12. Install the trim to both cowl side inner panels.
    13. Install the air bag control module (ACM) and bracket to the floor panel tunnel.
12. On diesel models, install the battery tray and battery.
13. Connect the negative battery cable.
14. Run the engine to normal operating temperatures; then, check the climate control operation and check for leaks.

1. Disconnect the negative battery cable.
   
   CAUTION

   After disconnecting the negative battery cable, wait 2 minutes for the driver-s/passenger-s air bag system capacitor to discharge before attempting to do any work around the steering column or instrument
2. If equipped with air conditioning, perform the following procedure:
   1. Discharge and recover the air conditioning system refrigerant.
   2. Disconnect the suction line jumper from the evaporator
   3. Remove the filter/drier and bracket-to-heater/air conditioning housing and cowl panel screws; then, move the filter/drier, bracket and refrigerant lines toward the center of the vehicle.
   4. Disconnect the wire harness connector from the fin sensing cycling clutch switch.
   5. Disconnect the wire harness connectors from the blower motor resistor and the high speed blower motor relay.
3. Cover the alternator to protect it from coolant spillage.
4. Drain the cooling system into a clean container for reuse.
5. Disconnect the heater hoses from the heater core tubes.
6. Remove the right headlight assembly, the grille panel, the right cowl grille support panel and the right radiator core support assembly.
7. Remove both lower heater/air conditioning housing flange-to-blower housing screws.
8. In the passenger-s compartment, perform the following procedures:
   1. From the top of the distribution duct, disconnect the blend-air door motor link.
   2. Reach through the glove box opening and remove the heater/air conditioning housing-to-dash panel stamped nuts (2) and screw (1). The fasteners are located below the distribution duct.
   3. Reach through the glove box opening; then, remove the 2 heater/air conditioning housing-to-dash panel stamped nuts. The nuts are located above the distribution duct.
9. In the engine compartment, remove the heater/air conditioning housing-to-dash stamped nut.
10. Carefully, separate the lower heater/air conditioning housing from the blower housing.
11. Pull the heater/air conditioning housing from the dash until the blend-air door link is clear of the dash panel hole.
12. Remove the heater/air conditioning housing assembly from the vehicle and place it on a bench with the top cover facing upward.
13. Disassemble the heater/air conditioning housing assembly by performing the following procedure:
    1. Remove the blend-air door pivot shaft nut.
    2. Remove the blend-air door link-to-rear mounting flange boot.
    3. Remove the blend-air door link, the boot and the lever as a unit.
    4. Remove the high speed blower motor relay mounting bracket-to-heater/air conditioning housing screw and remove the relay and bracket.
    5. Remove the top cover-to-heater/air conditioning housing screws and the cover.
14. Remove the heater core tube support bracket-to-mounting boss screw and remove the heater core from the heater/air conditioning housing assembly.
    
    
    

    

    Fig. View of the air conditioning fin sensing cycling clutch switch-1999-01 Dodge Ram Van/Wagon shown, others similar
    View of the air conditioning fin sensing cycling clutch switch-1999-01 Dodge Ram Van/Wagon shown, others similar
    
    
    

    

    Fig. Exploded view of the heater/air conditioning housing and related components-1999-01 Dodge Ram Van/Wagon shown, others similar
    Exploded view of the heater/air conditioning housing and related components-1999-01 Dodge Ram Van/Wagon shown, others similar
    
    
    

    

    Fig. View of the heater core-1999-01 Dodge Ram Van/Wagon shown, others similar
    View of the heater core-1999-01 Dodge Ram Van/Wagon shown, others similar

To install:

1. Install the heater core to the heater/air conditioning housing assembly and heater core tube support bracket-to-mounting boss screw, then, tighten the screw to 20 inch lbs. (2.2 Nm).
2. Assemble the heater/air conditioning housing assembly by performing the following procedure:
   1. Install the top cover and the cover-to-heater/air conditioning housing screws.
   2. Install the high speed blower motor relay and mounting bracket, then install the relay and bracket -to-heater/air conditioning housing screw.
   3. Install the blend-air door link, the boot and the lever as a unit.
   4. Install the blend-air door link-to-rear mounting flange boot.
   5. Install the blend-air door pivot shaft nut.
3. Install the heater/air conditioning housing assembly into the vehicle.
4. Push the heater/air conditioning housing into the dash until the blend-air door link falls into the dash panel hole.
5. Carefully, assemble the lower heater/air conditioning housing to the blower housing.
6. In the engine compartment, install the heater/air conditioning housing-to-dash stamped nut.
7. In the passenger-s compartment, perform the following procedures:
   1. Reach through the glove box opening; then, install the 2 heater/air conditioning housing-to-dash panel stamped nuts. The nuts are located above the distribution duct.
   2. Reach through the glove box opening; then, install the heater/air conditioning housing-to-dash panel stamped nuts (2) and screw (1). The fasteners are located below the distribution duct.
   3. At the top of the distribution duct, connect the blend-air door motor link.
8. Install both lower heater/air conditioning housing flange-to-blower housing screws.
9. Install the right radiator core support assembly, the right cowl grille support panel, the grille panel and the right headlight assembly.
10. Connect the heater hoses to the heater core tubes.
11. Refill the cooling system.
12. Uncover the alternator.
13. If equipped with air conditioning, perform the following procedure:
    1. Connect the wire harness connectors to the blower motor resistor and the high-speed blower motor relay.
    2. Connect the wire harness connector to the fin sensing cycling clutch switch.
    3. Install the filter/drier and bracket-to-heater/air conditioning housing and cowl panel screws.
    4. Connect the suction line jumper to the evaporator
    5. Evacuate and charge the air conditioning system refrigerant.
14. Connect the negative battery cable.
15. Run the engine to normal operating temperatures; then, check the climate control operation and check for leaks.

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For more help,please check this direct link:---

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http://technoanswers.blogspot.com/2011/11/how-to-replace-heater-core-for-all-car.html

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