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GEMS Sensor wire and setup


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I have a link G4+ Extreme that i want to wire some sensors in that i removed from some SPA gauges i had.

I have an oil and fuel pressure sensor that are the same and a water and oil temp sensor which are also the same.

There are 3 wires in all 4 sensors -

A Red and a Black wire which are both wrapped in some foil shielding and an exposed braid as the 3rd wire.

I wired the black wires into the sensor ground (pin 24 on A connector)

I wired the red wires into the 5v out (pin 32 on A connector)

Open braided wire into spare AN pins.


Setup calibration on CAL 4 as fuel pressure and set to 0.45 - 4.5. 

Tried that on all 4 sensors incase i had them wrong one (they all look the same) and it made no difference on any of them.

Have i wired them in wrong?

This is a link to the data sheet for the pressure sensors, mine is a GEMS 3100H

https://www.gemssensors.com/~/media/files/resources/na_english/catalogpages/catalog-h_3100series-3200series.ashx?fbclid=IwAR3Yzlqvvx1Kx_YDulCKLDvBi1seGmzOJfBxJd9JJVUcCSrDupLFazVhhQE

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If you hit F12 you can see it in the analog tab. This is the instantaneous value only.

To log it, go into the settings for you analog input and change the type to Voltage 0-5. This will make it log raw voltage values.

image.png.525cc328120fe1dda4f937aba90b2a40.png

Then go to the logging screen and add in AN volt6 or whatever input it is. 

Some input (like TPS) you can see raw voltage and calibrated value side by side by adding in the ANVolt# number to a log instead of TPS% or whatever the sensor is. This doesnt seem to work for pressure sensors though.

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sounds like the sensor pinouts are not what you think they are.

try sticking 3x AA batteries together in series to get a 4.5v signal, and this should be close enough to 5v to drive them. get out your multimeter and measure from the negative terminal of the batteries  to the signal wire. Even out of the car you should still see 0.5v or 1v on the signal wire at atmospheric pressure. There are only a handful of possiblities. remember to test + & - both ways around. 

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So i did the test.

 

Red on +, Black on -, Braided on volt meter = 0.77v

Black on +, Red on -, Braided on volt meter = 4.5v

All other combinations = 4.5v

So according to that it was wired correctly? 

I only tried a couple of sensors which seem to be the same. If i tried my fuel pressure sensor then turn the fuel pump on the ECU, i should see some voltage change shouldn't i?? Due to the pressure increasing?

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3 hours ago, AlexLSX7 said:

I only tried a couple of sensors which seem to be the same. If i tried my fuel pressure sensor then turn the fuel pump on the ECU, i should see some voltage change shouldn't i?? Due to the pressure increasing?

Yes, voltage should increase with pressure.

So are these only 2 wires and a shield?  That doesnt match the datasheet you linked.  Whats the full part number?  It sounds like they might be the 4-20mA versions rather than voltage.

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So I did the fuel pump test.

I did the red wire on +, black wire on - and the braided wire on the + on the voltmeter. I got a reading of 0.77 the same as last time. Turned the pump on and no change.

I tried the red wire on +, braided wire on -, black wire on + on voltmeter. Reading was 0.76. turned the pump on and it went up to 1.68 then floated around there. Turned the second pump on and it went up to around 1.78 until I'm guessing the pressure equalised a bit and went back to floating around 1.68. Once I turned off the pumps the reading slowly went back to 0.76.

So would I be right to assume that the red wire is 5v, the braided is ground and the signal wire is the black?

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10 hours ago, AlexLSX7 said:

So I did the fuel pump test.

I did the red wire on +, black wire on - and the braided wire on the + on the voltmeter. I got a reading of 0.77 the same as last time. Turned the pump on and no change.

I tried the red wire on +, braided wire on -, black wire on + on voltmeter. Reading was 0.76. turned the pump on and it went up to 1.68 then floated around there. Turned the second pump on and it went up to around 1.78 until I'm guessing the pressure equalised a bit and went back to floating around 1.68. Once I turned off the pumps the reading slowly went back to 0.76.

So would I be right to assume that the red wire is 5v, the braided is ground and the signal wire is the black?

It sure sounds like you have correct pins now.  Although the 0.76V seems odd, I would expect 1V at zero pressure.  Reading the datasheet again it looks like it might need more than 5V supply.  Do you have the SPA gauges still so you can measure what they were supplying?  I suspect 12V.

UuEeQ0T.png

 

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2 hours ago, Adamw said:

It sure sounds like you have correct pins now.  Although the 0.76V seems odd, I would expect 1V at zero pressure.  Reading the datasheet again it looks like it might need more than 5V supply.  Do you have the SPA gauges still so you can measure what they were supplying?  I suspect 12V.

UuEeQ0T.png

 

Yeah i do have them still, i will give them a try tonight. 

I just found a manual online for the gauges, if you look at page 7 it says it has 5v signal with a 10k pulldown, do i need to put a 10k resistor in line with it? It also says that the black wire is the pressure signal and the green wire is the ground, although the wire is not green in mine its just an open braid, but it did have a tiny bit of green sleeve on it when i took them off.

http://www.spa-uk.co.uk/spa/docs/DG52 (50 issue 3).pdf

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