Question about 2003 Jeep Grand Cherokee
I am trying to figure out what the wires for my map sensor are according to their color. I cannot find any sites that say what each one is...There are three wires and I know that one is is +V, one is the ground, and one goes to the ECU but the colors aren't always what they appear to be. Sso I am wondering if anyone knows what each one of these wires should look like on my 2003 Grand Cherokee?
On a 3-wire MAP sensor connector when looking at the vehicle "wiring harness mating side of the connector" (and not the sensor connector) - with the snap detent pointing UP and looking LEFT to RIGHT the signals will read >
GROUND > MAP SIGNAL > POWER
Hopefully we are talking about a MAP sensor, and NOT a MAF sensor as the 2 are different as to the wiring signals.
Color of the wires doesn't matter, as you are just looking for backprobed voltage SIGNALS only using an adapter if you are doing in-circuit signal testing.
POWER I believe should be in the 5-volt range unless Jeep is using 3.3-volt.
Usually the MAP SIGNAL voltage range is quite a bit lower on the sense line, but with Jeep you never know? If using a good DVM measuring the MAP SIGNAL voltage you should see a smooth decrease in voltage as the vacuum is increased. If there is no voltage change or negative swing then the sensor may either be bad or else you have an OPEN or SHORTED wire between one of the 3 connector leads and the PCM computer, which would be rare.
I take you are troubleshooting a specific CHECK ENGINE CODE hopefully, as if not I would have the PCM read properly with a good CAN OBD II code reader to pinpoint the troublesome sensor.
I've always used an ACTRON CP9087 Sensor Tester, and a CEN-TECH 94169 CAN OBD II code reader which works great for me.
Make sure your MAP vacuum line is good and hooked up right as well.
Let me know what you find?
Posted on Aug 13, 2008
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Fig. Fig. 3: MAP sensor location-3.3L and 3.8L engines
The PCM supplies 5 volts of direct current to the Manifold Absolute Pressure (MAP) sensor. The MAP sensor then converts the intake manifold pressure into voltage. The PCM monitors the MAP sensor output voltage. As vacuum increases, the MAP sensor voltage decreases proportionately. Also, as vacuum decreases, the MAP sensor voltage increases proportionally.
With the ignition key ON , before the engine is started, the PCM determines atmospheric air pressure from the MAP sensor voltage. While the engine operates, the PCM figures out intake manifold pressure from the MAP sensor voltage. Based on the MAP sensor voltage and inputs from other sensors, the PCM adjusts spark advance and the air/fuel ratio. The MAP sensor is mounted to the intake manifold, near the throttle body inlet to the manifold. The sensor connects electrically to the PCM.
Fig. Fig. 4: Disengage the MAP sensor connector-3.0L engine shown
WARNING When testing the MAP sensor, make sure the harness wires do not become damaged by the test meter probes.
Fig. Fig. 7: Using a digital volt-ohmmeter, test the MAP sensor voltage-3.0L engine shown
REMOVAL & INSTALLATION
See Figures 1, 2, 3 and 4
The MAP sensor is mounted on the intake manifold near the throttle body inlet to the manifold.
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Fig. Fig. 1: Blow through the sampling tube (A) when testing the MAF sensor
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MAP Sensor TESTING
See Figures 1, 2 and 3
Fig. Fig. 1: Typical Manifold Absolute Pressure (MAP) sensor wiring diagram (wire color, terminal identification/location may vary on certain models)
Fig. Fig. 2: Using jumper wires and a high impedance voltmeter test between MAP sensor terminals A and C with the key ON and engine off. The voltage should be approximately 5 volts
Fig. Fig. 3: Next test between MAP sensor terminals A and B with the key ON and engine off. The voltage should be approximately 0.5 volts
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OPERATION The Manifold Absolute Pressure (MAP) sensor, used on 1996-99 vehicles, measures the changes in intake manifold pressure which result from engine load/speed changes, and converts this information to a voltage output. The MAP sensor reading is the opposite of a vacuum gauge reading: when manifold pressure is high, MAP sensor value is high and vacuum is low. A MAP sensor will produce a low output on engine coast-down with a closed throttle while a wide open throttle will produce a high output. The high output is produced because the pressure inside the manifold is the same as outside the manifold, so 100 percent of the outside air pressure is measured.
The MAP sensor is also used to measure barometric pressure under certain conditions, which allows the PCM to automatically adjust for different altitudes.
The MAP sensor changes the 5 volt signal supplied by the PCM, which reads the change and uses the information to control fuel delivery and ignition timing.
TESTING See Figures 1 and 2
Fig. Fig. 1: Manifold Absolute Pressure (MAP) sensor circuit
When pumping up and releasing the vacuum, check to make sure the voltage readings are smooth. When applying vacuum to the sensor, the change in voltage should happen instantly. A slow change in voltage could point to a faulty sensor.
Fig. Fig. 2: MAP sensor voltage specifications
REMOVAL & INSTALLATION
3.8L (VIN K) Engine
See Figure 4
On these engines, the MAP sensor is mounted to the PCV valve cover.
Fig. Fig. 4: On the 3.8L (VIN K) engine, the MAP sensor (1) is mounted in the PCV valve cover (2)
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