Diagnostic Procedure

The ECC system should be considered as a possible source of trouble on engine performance, fuel economy and exhaust emission complaints ONLY after normal checks (which apply to vehicles without ECC) have been performed.
Diagnosis of the ECC system consists of 1 initial check: Diagnostic Circuit Check. This check will specify a specific chart for locating source of problem in ECC system.
When performing tests on ECC system, always insert test meter leads from harness side of connector. Always check connectors while still connected, unless specified otherwise in test charts.
Always perform the Diagnostic Circuit Check before and after any repairs to the ECC system.

Fig 1: ECC Test Connector Locations These connectors are located below steering column.

ECM TROUBLE CODE IDENTIFICATION

Trouble Code	Test Mode	Circuit Affected
11	Regular	Carter carb. high altitude mode
12	Regular	Carter carb. sea level mode
13	Regular	Duty cycle solenoid remains off
14	Test only	Vacuum switch I remains off
15	Regular	Solenoid valve III remains off
21	Regular	Hitachi carb. high altitude mode
22	Regular	Hitachi carb. sea level mode
23	Regular	Oxygen sensor
24	Test only	Vacuum switch II remains off
25	Regular	Solenoid valve I remains off
31	Regular	Duty cycle solenoid remains on
32	Regular	Thermo sensor
33	Test only	Feedback system
34	Regular	Auto. choke power remains off
41	Test only	Vacuum switch I remains on
42	Test only	Vacuum switch II remains on
43	Regular	Auto. choke power remains on
51	Regular	Solenoid valve III remains on
52	Regular	Solenoid valve I remains on