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Discussion Starter #1
I've got a P1105 map/baro solenoid code on my 2000 Frontier. Tested the solenoid, it's good. Tested the sensor, got power ground and the 5volt reference. Vacuum hoses are properly routed. Only thing I can't figure is that when I apply throttle, the 5 volt reference signal doesn't change. I assume it would right? But if not, where do I go next? Test at the ECU? Anybody happen to know what pin on the ECU I would test for the Map sensor? Thanks in advance.
 

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Thanks. Yeah by the looks of it, the voltage should be changing when I hit the throttle. But it just remains constant at about 4.5 volts
 

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So typically reference voltage doesn't change, that's why it's called the reference voltage. It's always the same and the measured voltage it compared to the reference voltage. The reason to supply reference voltage is for precise measurements where performance of the system can fluctuate between vehicles. If the sensor only compared to 5v nominal instead of reference/actual voltage, then if something happened to the system and you were only sending 4.3v to the sensor measurements get screwy and bad things start happening to the engine.
 
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