Hllo. i am corently at a project, of making a digital dashboard. to make this, i will read the signals from my audi 80 b4 1992 1,6 lt, sensors, and with arduino, i will calculate the speed/rpm/temp and fuel , in my pc! i could take the signals directly from the dashboard, but mine is completly broken down...
So i was wandering, can some1 point me to a direction, where are the sensors located, and more mporantly, what readings do they give??

 

Speed sensor is located on the transmission bell housing to probe the flywheel speed
Temp sensor should be located in one of the metal cooling pipes.
Fuel sensor is located inside the tank

Not sure how you mean readings. Generally between a certain volt is how a reading is calculated.

You would need a factory Bentley manual to know what the range is.

 

and what about the rpm??
By readings, i mean, do they give Ohm, or voltage diferences? in AC or DC etc...

 

I believe the RPM also goes into the transmission, not positive. I could not find the sensor for the tachometer.

The measure is usually resistance as each sensor has a switch inside which opens or closes per Ohms.
The system runs on 12v DC

 

well i have found all the sensors.. rpm is AC voltage between 0.1 and 0.28 volt..
Fuel and Temp. are just ohms,
But i cant seem to figure how the speed sensor works... its above the transmision box. it has a constant 12-13v dc outpout, but i cant see anythign that changes with my speed... any ideas?

 

Did a search, this should sum it up.

Introduction

Speed sensors take the place of the speedometer gear in conventional speedometers. A conventional speedometer was mechanically driven by a cable in a housing that was spun by a gear in the tail shaft or rear of the transmission. This driven gear could be replaced with several different sizes to compensate for different size tires or a change in the final drive gear in the rear axle housing.

Signals

The speed sensor gives off an electrical signal when rotated that is used by the computer to calculate speed. This signal transferred to the speedometer to illustrate speed. It to can be re-calibrated to compensate for differences in tires and final gears. The speed sensor is situated in the tail housing of a conventional rear wheel drive vehicle. In front wheel drive vehicles, it is situated on the top-side of the transmission on the differential housing near the drive axles. It has an electrical connector.

What it Does

A vehicle speed sensor output is used in a fuel-injected engine for a variety of things. It will give the computer information as to speed and is also used by the computer for adjusting the shift levels or speeds on the transmission. It is used for cruise control and for distance measurement used in the odometer which indicates the elapsed mileage. <b>The speed sensor is a signal generator of the magnetic type and produces a pulsing voltage at three miles per hour and higher.</b> The input to the computer from the sensor is also used by the computer to determine when to lock the doors on some vehicles and is sensory input for various new stabilizing and handling technology.

 

cool thanks! i will see what i can find!

 

well. as it turns the final results are those: (in case some1 bumps here by search)
the two sensors above transmision box are: the one mesures your speed, (i dont know how cause i will do my project with gps..)
and the other one, has +12v outpout when you DONT have reverse gear. so that one is used to see if you have reverse!
As for the RPM. it turns out that the car uses Hall effect sensor, wich is located,next to the SPARK allocator (the cluster where the 4 sparks get theit power from). it has 3 pinouts. 2 have constant 12v, and the other one switches between GND and +12V hence, creating the square wave!! thanks allot for the help!

 

so... i have some updates..

as it turns out, i have a 3wire ignition coil. that is located, in a diferent place than then distributor. the 3 wires, are supposed to be +12v, gnd , and signal.... so, the ignition module, is mounted on the ignition coil itself!! and it gets the signal to fire, from the ECU....

but i cant find ANY ecu at all???? i have searched all the car, and i cant seem to find any ECU mounted on it... maybe it was in the speedometer?? but i have completly removed my speedometer... how can then the car work??

 

ECU is located above the glove box behind the dash panel.