The following instructions are for testing the Crank Position Sensor (CPS) and Ignition Control Module (ICM) for Reatta models '88-'90 when the engine will not start.

This tutorial is not intended to diagnose a CPS that is failing intermittently, although it might be useful for that purpose. Read this entire tutorial before attempting to perform the tests in this tutorial. Please click here and read our disclaimer before using this tutorial.

This tutorial is intended for Reatta owners who have experience in working with hand tools and are familiar with the safety practices related to working around the moving parts of an engine. All safety precautions should be strictly adhered to.

Tools Needed:

  • Analog or Digital Multimeter .
  • Wire piercing probe attachment for multimeter lead or long sharp pin. (see photo below)
  • CPS Tester (if your digital volt meter won't detect the CPS signal) 
    Instructions for building a tester can be found here
  • Contact cleaner for cleaning wires.
  • 1-1/8" socket and ratchet.

Before you begin the tests:

  • Make sure the battery is in good condition and fully charged. A low battery could affect test results.
  • Clean wires at Ignition Control Module (ICM) connector and remove tape if needed to be able to see wire colors.

    This tutorial requires piercing the insulation of the wires going into the ICM . Be very careful not to damage the wires. An alternate method may be used as long as you can connect the meter and tester as described in each test. If you don't feel comfortable about piercing the wires do not proceed with this tutorial. Please see the chart at the bottom of this page for references to wiring colors and designations.

The following tests should be performed in sequence.


 Wiring diagram for reference



Thanks to members of the AACA Reatta forum for this information.

ATTENTION: Any advice or information found on this website should not be considered 100% accurate. Use any information you find here at your own risk. Carefully read and agree to the DISCLAIMER AND FAIR USE NOTICE before using any information found on this website.