chapter 15, 16, 17, 18

What are the uses of a MAP sensor by the PCM?

Engine Load Altitude EGR system diagnosis Detect deceleration (All of These)

What happens to the voltage measured at the ECT sensor when the thermostat opens?

Increases slightly

Which sensor does the TP sensor backup if the PCM determines that a failure has occurred?

MAF and MAP sensor

When testing the ECT sensor with the connector disconnected, the technician should select what position on theDMM?

Ohms

What change(s) will you notice on the MAF signal wire will occur as engine speed (RPM) is increased?

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Which wire on a TP sensor should be back probed to check the voltage signal to the PCM?

Signal

As the load on an engine increases, the manifold vacuum decreases and the manifold absolute pressure _______.

increases

Which is not a purpose or function of the MAP sensor?

measures engine speed

A technician attaches one lead of a digital voltmeter to the ground terminal of the TP sensor and the other meter lead to the negative terminal of the battery. The ignition is switched to on, engine off and the meter displays 37.3 mV. Technician A says that this is the signal voltage and is a little low. Technician B says that the TP sensor ground circuit has excessive resistance. Which technician is correct?

neither

What is the designated name of a fuel-injection system that does not use a sensor to measure the amount (or mass) of air entering the engine is usually called a(n)________ type of system?

speed density

ASE Style Question: Technician A says that MAP sensors use a 5-volt reference voltage from the PCM. Technician B says that the MAP sensor voltage will be higher at idle at high altitudes compared to when the engine is operating at near sea level. Which technician is correct?

technician A

Two technicians are diagnosing a poorly running engine. There are no diagnostic trouble codes. When the MAF sensor is unplugged, the engine runs better. Technician A says that this means that the MAF is supplying incorrect air flow information to the PCM. Technician B says that this indicates that the PCM is defective. Which technician is correct?

technician A

By its definition, how does a typical NTC temperature sensor work?

the resistance goes down when the temperature goes up

True or False: A TP sensor may be tested using a scan tool in the graphing mode?

true

true or false If the transmission fluid temperature (TFT) sensor were to fail (Open Circuit or as if unplugged), the PCM/TCM would react by altering the transmission shifting points.

true

Most TP sensors have how many wires?

3

The typical MAF reading on a scan tool with the engine at idle speed and normal operating temperature is _____.

3 to 7 grams per second

When checking the ECT sensor with a scan tool, about what temperature should be displayed if the connector is removed from the sensor (open circuit) with the key on, engine off?

-40°F (-40°C)

A Typical Throttle Position Sensor (TP sensor) voltage at idle is about ________.

0.5 volt or 10% of WOT TP sensor voltage

Which statement is false? Absolute pressure is equal to barometric pressure plus intake manifold vacuum. A decrease in manifold vacuum means an increase in manifold pressure. The MAP sensor compares manifold vacuum to a perfect vacuum. Barometric pressure minus the MAP sensor reading equals intake manifold vacuum.

Absolute pressure is equal to barometric pressure plus intake manifold vacuum.

Which design of MAP sensor produces a frequency (digital) output signal?

Capacitor-capsule

When measuring the output signal of a MAP sensor on a General Motors vehicle, the digital multi-meter should be set to read _________________.

DC V

When testing an ECT sensor on the vehicle with the engine running (dynamically), a digital multimeter can be used and the signal wires back probed. What setting should the technician use to test the sensor?

DC Volts

The sensor that most determines fuel delivery when a fuel-injected engine is first started is the ________.

ECT sensor

Two technicians are discussing the IAT sensor operation. Technician A says that the IAT sensor is more important to the operation of the engine (higher authority) than the ECT sensor. Technician B says that the PCM will add fuel if the IAT indicates that the incoming air temperature is cold. Which technician is correct?

Technician B

After a TP sensor has been tested using the min/max function on a DMM, a reading of zero volts is displayed. What does this reading indicate?

The TP sensor is open at one point during the test

After a TP sensor has been tested using the min/max function on a DMM, a reading of 5 volts is displayed. What does this reading indicate?

The TP sensor signal is shorted to 5-volt reference.

A P0122 DTC is retrieved using a scan tool. This DTC means __________________.

The TP sensor voltage is low The TP sensor could be shorted-to-ground The TP sensor signal circuit could be shorted-to-ground

Which sensor has a switch that controls the electric fuel pump?

VAF

What are the three industry approved ways that temperature sensors can be accurately tested?

Visual Inspection, DMM Voltage/Resistance, Scan tool

A typical MAP compares the vacuum in the intake manifold to ____________.

a perfect vacuum

Explain how the clear/flood mode operates in an OBDII vehicle??

accelerator pedal depressed all the way down to open throttle during cranking and pcm will greatly reduced or eliminate fuel injection to clear fuel from engine.

A MAF sensor on a General Motors 3800 V-6 is being tested for contamination. Technician A says that the sensor should show over 100 grams per second on a scan tool display when the accelerator is depressed to WOT on a running engine. Technician B says that the output frequency should exceed 7000 Hz when the accelerator pedal is depressed to WOT on a running engine. Which technician is correct?

both

A P0102 DTC is being discussed. Technician A says that a sensor circuit shorted-to-ground can be the cause. Technician B says that an open sensor voltage supply circuit could be the cause. Which technician is correct?

both

A P0107 DTC is being discussed. Technician A says that a defective MAP sensor could be the cause. Technician B says that a MAP sensor signal wire shorted-to-ground could be the cause. Which technician is correct?

both

A P0118 DTC is being discussed. Technician A says that the engine may currently be or had been overheated. Technician B says that the signal wire could be open. Which technician is correct?

both

ASE Style Question: Two technicians are discussing testing MAP sensors. Technician A says that voltage on a General Motors vehicle at idle should be about 1.0 volt. Technician B says MAP sensor frequency on a Ford vehicle at idle should be about 105-108 Hz. Which technician is correct?

both

What is the purpose of a MAF sensor?

calculate the airflow of the engine for proper fuel air mixture

Air that enters the engine without passing through the air flow sensor is called ____________.

false air

Which type of sensor uses a burn-off circuit?

hot wire MAF sensor