ECC Diagnosis: Notes

Diagnosis of the ECC system is done in the following order:

1. Ensure that all engine systems NOT related to ECC are fully operational. DO NOT  proceed with testing unless you are sure that all other problems have been corrected.
2. ECC diagnosis is performed in 2 modes: Regular mode and test mode. Most of the trouble codes can be activated in regular mode test. Some codes require that the test mode option be entered to activate display of codes. To enter test mode, the test mode connector must be connected together. See Fig 1 .
   NOTE: The test mode connector must not be connected together unless specific tests require that it be connected. Connector must be disconnected after performing any tests.
   Fig 1: ECC Test Connector Locations Connectors are located near ignition coil in the engine compartment.

   
3. When a malfunction occurs in the ECC system, the ECM lights the "ECS" lamp on the instrument panel and causes the oxygen sensor monitor lamp to flash a trouble code. Trouble codes are displayed in numerical order from lowest code to highest code.
4. Trouble codes are displayed by flashes of the oxygen sensor monitor lamp on the ECM. In regular mode or test mode, a trouble code will be displayed by the oxygen sensor monitor lamp only when the "ECS" lamp is on. Trouble codes are 2-digit numbers.
5. An example of trouble codes is as follows: "FLASH", "FLASH", pause, "FLASH", "FLASH", "FLASH" followed by a longer pause identifies trouble code "23". The first series of flashes indicates first digit of trouble code; second series of flashes indicates second digit of trouble code.
6. The first digit is flashed for about 1.2 seconds with a 0.3 second pause between each flash. The second digit is flashed for about 0.2 seconds with a 0.3 second pause between each flash. Each trouble code is separated by a 1.8 second pause. Trouble codes display repeatedly until malfunction is repaired.