I purchased a 5vdc 0.5-4.5v 0-100 psi transducer to monitor fuel rail pressure in my 04 Silverado 6.0 swap. I recently purchased the MPVI2 pro kit I will be monitoring through. My question is where can I get a 5vdc signal to drive the transducer? Or would I need a separate power supply for this?
Thanks.
plenty of 5vdc circuits from the pcm...TPS, EGR, A/C, etc and even some that are not used..tap into one of them
I guess that?s my question though.
Pardon my ignorance but if I knew where the unused 5vdc sources were in the PCM I wouldn?t have asked the question.
You can usually run more than one sensor off a single +5v supply wire. Just tap into an existing one. Internal in the PCM there isn't a dedicated supply for each individual sensor, it's one (or a few) voltage regulators that split internally and feed multiple pins.
If you want to find a separate +5v pin that's unused in your harness, you'll have to backprobe the blank spots in the PCM connectors. Just comparing pinouts from other applications that used a P59 isn't enough, there could be pins that are unused in ANY application but still provide what you want.
In a 2004 Silverado 4.8/5.3/6.0 P59, there are only 4 +5v ref pins in use. C1 7(IPC), 45(RPS), 46(FTP), 48(MAP).
In a 2004 Silverado 4.3 P59, there are 5 in use. C1 pin 8 is blank in the V8 harness, in the V6 it's the +5v for the TPS (DBW trucks get TPS +5v from the TAC not PCM). Backprobe that cavity and see if you have +5v. You may not, that pin may be turned off when using a DBW/V8 calibration. Don't know until you check it. If you just really think you need to use a separate pin for your new sensor.
And another thing.
In the V6 P59, the TPS signal return is at C2 pin 24, and it's unused in the V8 harness. That pin may be an 'unsupported parameter' in the scanner when using a V8 calibration but you should check it, if it works that may be an easy way for you to read/log your new sensor.
Thanks so much!
Since this is a swap, are you using any of the EVAP stuff? If not you can use the fuel tank pressure sensor wiring for both powering and reading your add-on sensor.
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im digging this up, i just need some clarification. I want to wire in 2 0-100 psi 5v transducers. pretty straight forward installs it seems. i have an extra harness im able to snag some pined wires from. My question is - i have 3 wire transducers 5v - Ground - Signal.Originally Posted by blindsquirrel
I notice for the fuel tank pressure sensor, there are three wires associated with it. But the ac pressure switch only has two. Do i just ground my Ground wires off the sensor ?
If an "A/C pressure sensor" has only two wires then it's an A/C pressure switch, not a sensor.
Looks like for a/c
pin 45 blue -5v reference
Pin 14 red - sensor signal
Is this correct? Just ground the ground ?
Nobody knows what you are working on if you don't tell us.
A "sensor" that has only two pins is not a sensor, it is a discrete on/off switch. Feels like I already said that. All the A/C pressure sensors have 3 wires: 5v, gnd, signal.
Does not appear I can simply add photos here- so I apologize for the unclear explanation.
From the beginning, I am looking to log fuel pressure (and eventually oil pressure) in hp tuners I have an mvpi2 ( no pro link )
I am using a generic 0-5v 0-100psi pressure transducer with three wires. Red black green. 5v 0v Signal.
I?ve used these types of transducers in many other scenarios , not this one yet however.
Generally you feed it 5v , give it ground, and the signal outputs a voltage relative to what the pressure is. (.5-4.5v usually with these)
I see people using EGR, AC pressure, and Fuel tank pressure pins on the ecu to log these values, with a little use defined math, I get all that part, easy peasy.
I want to use ac pressure sensor for this situation. The PCM Pinouts I?m looking at show
Blue pin 45- 5v reference
Red pin 14 - sensor signal
Doesn?t list a dedicated ground for this sensor, I notice some other sensor may have ?sensor ground? pins. In this circumstance - can I just ground the pressure transducer to.. well ground. ( to complete the 5v reference circuit ) or does it need to be pinned to a specific ground on the pcm?
I am NOT referring to the af pressure SWITCH pins, which are
Red pin 11 - ac high recirculating switch
Red pin 17 - ac request signal
Red pin 55 - ac low pressure switch signal
I have a standalone harness, these plugs and wires are not in the harness I am running my own wires.
You need to check the wiring diagram for whatever donor the ECM came from to confirm how the wiring should be. Pin outs for the ECM only tell so much.
GM used the phrase “low reference” for a while for sensor grounds grounded through the ECM.
Ok I may be confusing myself. i was looking at a pinout on this forum for a pcm, now im looking at one from https://www.lt1swap.com/99-02_vortec_pcm.htm
Which is a truck pcm - which i have. and it doesn't actually use the ac pressure sensor on here. But it does use fuel tank pressure. ill tap into that, which does provide the low reference pin. I originally tried to get my wideband to read through egr and i had trouble with it. so i gave up and used the serial connection ( which works perfect ) i am now revisiting this again and i just wanted as much information as possible. So , thank you for your help brother!
OK, so far you've narrowed it down to "a truck". Can you give a YEAR, a MAKE, and a MODEL? So I can go into the GM service manuals and find your actual diagrams?
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