Interfacing with 89 GMC Truck

Im working closely with a few programmers developing a program to help me interface with my gauge cluster. I have an 89 GMC Sierra and I will be using phidgets, www.phidgets.com for input. I know that the tach and some other things go off of like 2000ppm. What if I wanted to monitor the oil press, water temp, gas, and speedo. Does anyone know or can point me in the right direction to figure out what the sensors use to tell those things. I remember reading somewhere that the gas is between 0-90ohm depending on how full it is. Is there someone that knows for sure how the sensors transmit those things. Thanks for the help

You can ask the tech support guys over at Autometer for this information. I'm sure they will be of assistance to you.Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

i have updated an 83 jeep with new digital autometer guages and learned from that experience and from doing electrical repair in a mechanic shop for a while that they are all pretty much the same concept.  you will need to buy a few sender units for the speedometer, oil pressure, and water temp unless you get special guages made for cable driven speedo cars and analog temp cars.  they are easy to install and you don't need to "program" anything.  the fuel level should just hook up straighforwardly.  They work as follows:

Fuel Level - positive resistor based signal...the lower the fuel level, the higher the resistance

Speedo-Odo - cable on older vehicles, ground based square wave signal, the faster you go, the higher the frequency Oil Pressure - ground based resistor signal                                                                                                                                   Water Temp - ground based thermistor signal

"If a man made it, another can modify it...it just takes some thinking."

"If you ask questions, you're a fool for 5 minutes; if you don't, you're a fool for a lifetime."

for exact values for the signals, call a GM service center or check out a chilton or haynes manual (don't know if they have that info or not)"If a man made it, another can modify it...it just takes some thinking."

"If you ask questions, you're a fool for 5 minutes; if you don't, you're a fool for a lifetime."