help with codes 56 and 66.
- Thread starter rculjak
- Start date
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Code 56 MAF - output voltage too high. Failed MAF sensor, short between
MAF sensor and heater or short in wiring between pin A (12 volts) and pins C or D.
There are three parts in a MAF: the heater, the sensor element and the amplifier.
The heater heats the MAF sensor element causing the resistance to increase.
The amplifier buffers the MAF output signal and has a resistor that is laser
trimmed to provide an output range compatible with the computer's load tables.
The MAF output varies with RPM which causes the airflow to increase or
decease. The increase of air across the MAF sensor element causes it to cool,
allowing more voltage to pass and telling the computer to increase the fuel flow.
A decrease in airflow causes the MAF sensor element to get warmer, decreasing
the voltage and reducing the fuel flow. Measure the MAF output at pins C & D
on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9
on the computer.
At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt
Disconnect the MAF sensor, battery negative post and computer connector.
The computer connector is located under the passenger side kick panel & is
secured by a single 10 MM bolt. Do not make any resistance checks
without disconnecting the connectors. You will get incorrect readings.
Check the resistance between the MAF signal wiring and power.
Pin D on the MAF (dark blue/orange wire) and Pin A (red wire) should be
1 megohm or higher (meter shows infinite resistance or open circuit.).
Pin C on the MAF (tan/light blue wire) and Pin A (red wire) should be
1 megohm or higher (meter shows infinite resistance or open circuit.).
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
Code 66 MAF below minimum test voltage.
Insufficient or no voltage from MAF. Dirty MAF element, bad MAF, bad MAF wiring, missing power to MAF. Check for missing +12 volts on this circuit. Check the two links for a wiring diagram to help you find the red wire for computer power relay switched +12 volts. Check for 12 volts between the red and black wires on the MAF heater (usually pins A & B). while the connector is plugged into the MAF. This may require the use of a couple of safety pins to probe the MAF connector from the back side of it.
There are three parts in a MAF: the heater, the sensor element and the amplifier. The heater heats the MAF sensor element causing the resistance to increase. The amplifier buffers the MAF output signal and has a resistor that is laser trimmed to provide an output range compatible with the computer's load tables.
The MAF element is secured by 2 screws & has 1 wiring connector. To clean the element, remove it from the MAF housing and spray it down with electronic parts cleaner or non-inflammable brake parts cleaner (same stuff in a bigger can and cheaper too).
The MAF output varies with RPM which causes the airflow to increase or decease. The increase of air across the MAF sensor element causes it to cool, allowing more voltage to pass and telling the computer to increase the fuel flow. A decrease in airflow causes the MAF sensor element to get warmer, decreasing the voltage and reducing the fuel flow. Measure the MAF output at pins C & D on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9 on the computer.
At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt
Check the resistance of the MAF signal wiring. Pin D on the MAF and pin 50 on the computer (dark blue/orange wire) should be less than 2 ohms. Pin C on the MAF and pin 9 on the computer (tan/light blue wire) should be less than 2 ohms.
There should be a minimum of 10K ohms between either pin C or D on the MAF and ground.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif
To clean the MAF, remove the MAF element and gently spray it with electrical contact cleaner. You can also use non-flammable brake parts cleaner (same chemical in a bigger can & cheaper too). Let it dry and put it back in.
http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp
MAF sensor and heater or short in wiring between pin A (12 volts) and pins C or D.
There are three parts in a MAF: the heater, the sensor element and the amplifier.
The heater heats the MAF sensor element causing the resistance to increase.
The amplifier buffers the MAF output signal and has a resistor that is laser
trimmed to provide an output range compatible with the computer's load tables.
The MAF output varies with RPM which causes the airflow to increase or
decease. The increase of air across the MAF sensor element causes it to cool,
allowing more voltage to pass and telling the computer to increase the fuel flow.
A decrease in airflow causes the MAF sensor element to get warmer, decreasing
the voltage and reducing the fuel flow. Measure the MAF output at pins C & D
on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9
on the computer.
At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt
Disconnect the MAF sensor, battery negative post and computer connector.
The computer connector is located under the passenger side kick panel & is
secured by a single 10 MM bolt. Do not make any resistance checks
without disconnecting the connectors. You will get incorrect readings.
Check the resistance between the MAF signal wiring and power.
Pin D on the MAF (dark blue/orange wire) and Pin A (red wire) should be
1 megohm or higher (meter shows infinite resistance or open circuit.).
Pin C on the MAF (tan/light blue wire) and Pin A (red wire) should be
1 megohm or higher (meter shows infinite resistance or open circuit.).
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
Code 66 MAF below minimum test voltage.
Insufficient or no voltage from MAF. Dirty MAF element, bad MAF, bad MAF wiring, missing power to MAF. Check for missing +12 volts on this circuit. Check the two links for a wiring diagram to help you find the red wire for computer power relay switched +12 volts. Check for 12 volts between the red and black wires on the MAF heater (usually pins A & B). while the connector is plugged into the MAF. This may require the use of a couple of safety pins to probe the MAF connector from the back side of it.
There are three parts in a MAF: the heater, the sensor element and the amplifier. The heater heats the MAF sensor element causing the resistance to increase. The amplifier buffers the MAF output signal and has a resistor that is laser trimmed to provide an output range compatible with the computer's load tables.
The MAF element is secured by 2 screws & has 1 wiring connector. To clean the element, remove it from the MAF housing and spray it down with electronic parts cleaner or non-inflammable brake parts cleaner (same stuff in a bigger can and cheaper too).
The MAF output varies with RPM which causes the airflow to increase or decease. The increase of air across the MAF sensor element causes it to cool, allowing more voltage to pass and telling the computer to increase the fuel flow. A decrease in airflow causes the MAF sensor element to get warmer, decreasing the voltage and reducing the fuel flow. Measure the MAF output at pins C & D on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9 on the computer.
At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt
Check the resistance of the MAF signal wiring. Pin D on the MAF and pin 50 on the computer (dark blue/orange wire) should be less than 2 ohms. Pin C on the MAF and pin 9 on the computer (tan/light blue wire) should be less than 2 ohms.
There should be a minimum of 10K ohms between either pin C or D on the MAF and ground.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif
To clean the MAF, remove the MAF element and gently spray it with electrical contact cleaner. You can also use non-flammable brake parts cleaner (same chemical in a bigger can & cheaper too). Let it dry and put it back in.
http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp
Attachments
did you get your car fixed
because im going through all these problems also
i just baught the car and keep getting code 66
car runs great for 30 seconds until it trips code
i purchased a new maf and still haveing same problems
i talket the tech guy at the company and he told me that that reading is extreemly common when your injector size is 42lb or higher... i am going to get a custom chip burned on tues. at the shop when they are burning the chip they just need to make sure minimun test voltage on maf sensor is set to 0 and then you will be all good........ hope this helped..... its been a nightmare for me
because im going through all these problems also
i just baught the car and keep getting code 66
car runs great for 30 seconds until it trips code
i purchased a new maf and still haveing same problems
i talket the tech guy at the company and he told me that that reading is extreemly common when your injector size is 42lb or higher... i am going to get a custom chip burned on tues. at the shop when they are burning the chip they just need to make sure minimun test voltage on maf sensor is set to 0 and then you will be all good........ hope this helped..... its been a nightmare for me
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