Dodge Repair/97 dodge 1 ton van 360 gas: MAP sensor anomaly
QUESTION: I have a high voltage map sensor code. Have replaced computer and map sensor. I have checked computer grams and voltages, map sensor is showing on scanner to run close to 5 volts all the time. I took map sensor return wire to computer loose and return voltage with volt meter from map sensor shows to be 1.20 at idle and increases with throttle, but on scanner shows close to 5 volts all the time. I have 5 volts a reference signal at map sensor and a good ground. Any ideas? Thanks, Brad
ANSWER: Hi Brad,
I assume that the vacuum line to the sensor or its mounting to the manifold (if that is how it is set up) is 'tight'.
The 5v is of course the reference voltage for operation of the sensor. Typically one would expect the signal wire to be in the range of 4.6v with the key in the 'run' position but the engine not running (depends upon the barometric reading at the time where you are located (altitude/local weather). Then when you start the engine and at warm idle it should drop maybe to about 1.3-1.5v. It sounds like there may be a short in the wiring harness between the controller and the sensor wherein the signal wire is shorted to the reference voltage wire.
That is about all I can imagine would explaint this situation.
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QUESTION: Ok I guess you misunderstood question, I took map sensor reference wire loose at computer and with the van running at idle, with a volt meter voltage is about 1.2 volts and increases with throttle on the reference wire. I think it was pin 27, so map is doing its job, computer is not recognizing this though because on scanner it stays around 4.7 volts. I put three rebuilt computers and at that point I was convinced the rebuilds were bad so I tried a known good off a Identical dodge van and the same thing happened, it runs rich and code for map high voltage. Thanks for all your help.
What is the fault code number?
And what is scanner showing to be the the map signal voltage when the MAP is unplugged from the harness and the engine is off (but key in 'run') and when the engine is running?
And what does your volt-meter show the voltage to be on the that "open" signal wire at the harness plug when the engine is off and the engine is running?