What are the trouble codes for the MAP sensor?
On most OBD1 applications, there are two trouble codes associated with the MAP sensor. A code 33 will set if the MAP sensor output voltage is higher than expected (indicating low vacuum) and a code 34 will set if the MAP sensor output voltage is lower than expected (indicating high vacuum).
What should the output voltage of a MAP sensor be?
If you are getting a code 34 you should look for a collapsed or blocked vacuum line going to the MAP sensor or electrical problem between the ECM and sensor. Normal output voltage of a MAP sensor should be about 4.5 volts or so with key on, engine off; and less than 1.5 volts with engine running at idle.
How does a MAP sensor work on a car?
What Does a Map Sensor Do? Basically, a MAP sensor reads the amount of air pressure in relation to vacuum inside the intake manifold, either directly or using a vacuum hose. Then, it translates this pressure into a voltage signal that the sensor feeds to the power control module (PCM), your car’s computer.
How many bars of pressure difference does a MAP sensor read?
A 2-bar MAP sensor will read up to 2-bars of atmospheric pressure difference, and a 3-bar will read up to 3. But all of these sensors must still operate within the same voltage output specs as a 1-bar. So in order to accomplish this, the output voltage must be scaled accordingly.
What causes a bad code on a MAP sensor?
Remember that even though the code points to the potential problem, the particular circuit or component involved may not be at fault. Instead, a related component may have triggered the code. For example, in many applications a leaking vacuum hose or a bad throttle position sensor (TPS) may cause a trouble code that points to a faulty MAP sensor.
How does the MAP sensor work on a car?
MAP sensors measure the absolute air pressure (barometric pressure minus intake vacuum) in the intake manifold, which helps the engine CPU decide on the correct air/fuel ratio. The values it displays are pressures, measured in Inches of Mercury (in. Hg). 1 bar of pressure is equivalent to 29.4 in. Hg.
What should the voltage be on a MAP sensor?
Your voltage reading should be between 4.6 and 5 volts. Apply 5 in-Hg of vacuum to the sensor. The readout should be about 3.75 volts. Now apply 20 in-Hg of vacuum to the sensor. The voltage should be about 1 volts. Your readings may vary slightly, depending on altitude and current weather conditions.
Which is the output shaft speed ( OSS ) sensor?
The first is known as the input shaft speed (ISS) sensor. As described, this sensor is used to monitor the speed of the transmission’ input shaft. The other sensor is the output shaft speed (OSS) sensor.