hello guys,,i have a question, where do we use 5 volt ref? in input switch ,like map,tps ? or means that we use 5 volt ref,in every input and autput,switch ,and solenoid? i dont undestud this,, help me pls,,
5v Ref is used on almost all sensors on the vehicle. I say almost all because some manufactures will supply system voltage to the sensors like a crank or cam sensor. I ran into that on my 06 Nissan Altima case study which I posted about.
Usually there are a few different 5v REF circuits. Each Thermistor circuit has its own dedicated 5v REF circuit that it pulls down. These are usually 2 or even 1 wire sensors. All other sensors, boost/pressure sensors, MAF, TPS, Crank, Cam, etc, share one 5v ref circuit. If that one 5v REF circuit is pulled down at all, the rest of the sensors can't function as intended and could lead to a crank no start.
Even though most sensors share a 5v ref, that does not mean you will see one 5v ref wire leaving the PCM, you might see individual 5v ref wires leaving the PCM to various sensors but internally in the PCM share the same circuit.
Testing for a 5v ref is a good way of testing if the PCM is alive or not and will usually point you away or toward a PCM or PCM power and ground problem. This will usually be associated with a no communication problem.
In Pauls book he goes into this very well and also in his premium subscription on this website he has many many videos dealing with the 5v ref that have TONS of information. Its really worth the monthly subscription! If you search ScannerDanners youtube channel im sure he has some 5v ref videos there too.
scanner danners epm engine performance manual it explains it all I have went over multiple chapters multiple times and I am still learning its a journey to become a journeyman you must be prepared for a great journey
5v ref is a very stable voltage it is clean of any spikes a very stable voltage needed to get good accurate signals from the sensors, it can get pulled down by a shorted sensor but this is unlikely to damage the PCU.
5v is chosen for a couple of reasons, firstly it is well below the battery voltage during a cold start, secondly it fits in well with electronic computer logic voltages.
The 5v ref can be just that a reference voltage as on a TPS or refrence and power supply as on a hall effect cam sensor.
As I posted in your other thread a 2 wire temperature sensor 5v wire is slightly different.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
It can be both a highly accurate datum reference free of ripples and spikes and an accurately controlled supply voltage. Most automotive sensors work as voltage deviders.
Some sensors such as MAFs and 3 wire pressure sensors use the 5v ref as a power supply and reference datum.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
