Diagnosis & Testing: Preparation

Correct test results for system are dependent on the correct operation of several related non-EEC-IV components and systems. All non-EEC-IV problems should be corrected before attempting to diagnose the EEC-IV system.

Before hooking up any equipment to diagnose the EEC-IV system, make the following checks:

• Verify condition of air cleaner and air ducting.
• Check all vacuum hoses for leaks, restrictions, and proper routing.
• Check the EEC-IV system wiring harness and electrical connections for corrosion, loose or detached connectors, loose wires, terminals and proper routing.
• Check the ECA, sensors and actuators for physical damage.
• Perform all necessary safety precautions to prevent personal injury or vehicle damage.
• Set parking brake and place shift lever in "P" for automatic transmission and Neutral for manual transmission. DO NOT  move shift lever during testing unless specifically directed to do so.
• Turn off all lights and accessories. Ensure that vehicle doors are closed when making readings.
• Check and correct coolant level.
• Start engine and idle until upper radiator hose is hot, pressurized and throttle is off fast idle. Check for leaks around exhaust manifold, exhaust gas oxygen sensor and vacuum hose connections.
• If equipped, place octane switch in premium position.
• Turn ignition switch to "OFF" position. Service items as required, then go to EQUIPMENT HOOK-UP  .

If engine will not start, starts but stalls, idles rough or runs rough, see KEY ON/ENGINE OFF SELF-TEST  in this article. If any of the above conditions are still present after a code 11 in the KEY ON/ENGINE OFF SELF-TEST  , see CIRCUIT TEST A  in this article. If engine stalls or runs rough, see DIAGNOSIS BY SYMPTOM TEST  in this article.