BENCH TOP ATS/CTS TEST PROCEDURE AND EQUIPMENT

by

PATRICK "Luau Bob" WATT

Purpose

This procedure is a component level verification method for the Cosworth Vega's EFI air temperature sensor (ATS) and coolant temperature sensor (CTS).

Overview

The CTS and ATS are NOT thermistor type devices. Therefore, simple resistance measurements cannot be performed to verify the functionality of these sensors.  The CTS and ATS are transistor based sensors which require power to activate their circuitry.  This procedure was developed to provide an easy bench top method of sensor verification.  

Required Equipment

  1. 1 Digital Multi-function Meter (DMM)
  2. 1 Thermometer
  3. 1 10.0 Kohm resistor
  4. 1 9 V Radio Battery
  5. 1 9 V Radio Battery connector
  6. 2 spade receptacles (or any substitute) for sensor connection  
  7. Miscellaneous pieces of thin wire

Notes

  1. Sensor connections must stay dry if liquid is used to vary the temperature of the sensors.
  2. If you look closely at the top of the sensor you will see the + and - markings.
  3. The reference temperature graph was developed using a test fixture that simulated the ECU.  Accordingly this test setup will likely generate results that are not precisely those specified in the reference graph. However, they should be close.

Procedure

  1. Construct the test setup and make connections per the diagram.
  2. Measure the voltage across the sensor.
  3. Measure the temperature at/of the sensor.
  4. Compare the measured voltage to the value on the graph at the observed temperature.
  5. Repeat steps 1 through 4 at different temperatures.
  6. If the observed difference varies by more than 10 degrees from the graph (see Note 3), then the sensor is BAD.
  7. Optionally, send me your measurements so I can make a new graph.

TEST COMPLETE.

BENCH TOP TESTING SETUP

 

SENSOR REFERENCE GRAPH