link pressure sensors

[gtr-import]

hello guys,

try to have my Link ( variohm) pressure sensors data , oil pressure and fuel pressure with the link , but when I use the sensor brand in the list ( 150PSI TI sensor ) the reading is zero .

if I try another brand the data are wrong but it don't show zero , can I have some help for my sensor calibration , don't found calibration table anywhere for the Link sensor.

 

 

 

 

 

[cj]

Are you sure the pinout is correct, and is it a genuine TI sensor? There are some chinese clones where the pinouts are 1 pin off. 

Best way to check if its a wiring problem is to plug it in, turn the ecu/key/etc to ON, then press f12 on the laptop to bring up actual voltages. Click on the "analog" tab and check if you are seeing ~0.5v on whichever AnVolt input you have it wired to.

If you see 0v, 5v, or something else obviously wrong you have a wiring issue. If you see ~0.5v at atmospheric pressure, then apply some pressure to the system (turn on fuel pump or whatever), and check that the voltage jumps up some reasonable amount.

The calibration for these is really simple 0.5v = 0psi & 4.5v = rated psi (in your case 150psi). Set a custom calibration to these numbers, then assign this calibration to your anVolt.

[gtr-import]

thanks , i will check that , I hope they are not Chinese copy , they came from a Link dealer in UK.

[gtr-import]

just check the sensors , they are wired right , Ov is present at the right pin and 5v also ( 4,95V) .

I check at the ecu pin , I use AN volt 4 and 5 for my pressure sensors , I have approx 0,2 volts at the pin but PC link show me zero , even when the fuel pump is on , i didn't start the engine yet just left the ignition on , I prefer test all my sensor before cranck the engine.

[cj]

Am I understanding this right... all sensors are plugged in while you are testing, and you are just backprobing the pin/joint in the wire? [pin numbers may be wrong below]

pin 1) from 5v ecu ref, shows 5v at the sensor

pin 2) from ecu signal ground, show 0v/ground at the sensor

pin3 - the signal wire) show 0.2v at the sensor and 0v in the ECU?

Here are the things I would check:

1) make sure you have ground pin2 and not a floating pin - unplug the sensor and with the ecu on, check voltage with a multimeter ebtween pin 1 & 2. This verifies the wiring to both.

2) have you got anything else connected to that sensor wire? a factory dash gauge? another sensor? anything at all? with the sensor unplugged does the ECU see any voltage? You should also check the resistance between the signal ground and this signal wire, and compare this to the value of signal ground to any other unused anVolt wire. The values dont matter, but you want to look for differences that suggest there is another path to ground via a gauge/short/broken wire/something else other than the known good path through the ECU internals.

3) double check that you arent reading the connector pinout from the wrong side (eg male vs female). From memory, if you wire these sensors up to the wrong pins, you can get ~0.2 volts showing on what should be the ground pin or something like that. 

4) check the part number on your sensor - some are rated in current output instead of voltage, or at different scales than the usual 0.5-4.5. Unlikely if you bought it from a link dealer but easy to verify.

5) if its easy enough, disconnect the signal wire near the gauge, you can then measure the output voltage directly from the sensor without any chance of the ECU/other wiring pulling the voltage up or down. You only want the 5v & ground connected for this test. 3x AA batteries  stuck together can usually create a close enough to 5 ish volts to test a sensor  if you cant get into the wiring easily. Remember to probe sensor output with + and the battery negative with - on your meter. Chassis ground isnt connected if you are running from a battery.

As per the calibration, these sensors output only in the range 0.5 to 4.5v. At 0 pressure, your should still have 0.5v. Anything less than this means you have a wiring problem or a sensor fault.